/* Apple-inspired CSS with responsive design */
:root {
    /* Optimized Color Palette - Enhanced contrast and readability */
    --primary-blue: #1D4ED8;
    --primary-blue-dark: #1E40AF;
    --primary-blue-light: #3B82F6;
    --primary-blue-50: #EFF6FF;
    --primary-blue-100: #DBEAFE;
    --secondary-indigo: #4F46E5;
    --accent-emerald: #10B981;
    --accent-amber: #F59E0B;
    --accent-red: #EF4444;
    
    /* Neutral Grays - Better contrast */
    --gray-50: #F9FAFB;
    --gray-100: #F3F4F6;
    --gray-200: #E5E7EB;
    --gray-300: #D1D5DB;
    --gray-400: #9CA3AF;
    --gray-500: #6B7280;
    --gray-600: #4B5563;
    --gray-700: #374151;
    --gray-800: #1F2937;
    --gray-900: #111827;
    
    /* Surface Colors */
    --surface-white: #FFFFFF;
    --surface-light: #FAFBFC;
    --surface-card: #FFFFFF;
    --surface-elevated: #FFFFFF;
    
    /* Text Colors */
    --text-primary: #1F2937;
    --text-secondary: #4B5563;
    --text-tertiary: #6B7280;
    --text-inverse: #FFFFFF;
    
    /* Typography - Enhanced hierarchy */
    --font-family-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-family-mono: 'JetBrains Mono', 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', monospace;
    
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    --font-size-5xl: 3rem;
    
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    
    --line-height-tight: 1.25;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.75;
    
    /* Spacing System - 8px base grid */
    --space-1: 0.25rem;  /* 4px */
    --space-2: 0.5rem;   /* 8px */
    --space-3: 0.75rem;  /* 12px */
    --space-4: 1rem;     /* 16px */
    --space-5: 1.25rem;  /* 20px */
    --space-6: 1.5rem;   /* 24px */
    --space-8: 2rem;     /* 32px */
    --space-10: 2.5rem;  /* 40px */
    --space-12: 3rem;    /* 48px */
    --space-16: 4rem;    /* 64px */
    --space-20: 5rem;    /* 80px */
    --space-24: 6rem;    /* 96px */
    
    /* Borders and Shadows - Modern elevation system */
    --border-radius-sm: 0.375rem;   /* 6px */
    --border-radius-md: 0.5rem;     /* 8px */
    --border-radius-lg: 0.75rem;    /* 12px */
    --border-radius-xl: 1rem;       /* 16px */
    --border-radius-2xl: 1.5rem;    /* 24px */
    --border-radius-full: 9999px;
    
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    
    --border-light: 1px solid var(--gray-200);
    --border-medium: 1px solid var(--gray-300);
    --border-focus: 2px solid var(--primary-blue);
    
    /* Transitions - Refined timing */
    --transition-fast: all 0.15s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-normal: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, var(--primary-blue) 0%, var(--secondary-indigo) 100%);
    --gradient-surface: linear-gradient(145deg, var(--surface-white) 0%, var(--gray-50) 100%);
}

/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family-primary);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-normal);
    line-height: var(--line-height-normal);
    color: var(--text-primary);
    background: var(--surface-light);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-4);
}

/* Typography - Modern hierarchy */
h1 {
    font-size: var(--font-size-4xl);
    font-weight: var(--font-weight-bold);
    line-height: var(--line-height-tight);
    color: var(--text-primary);
    margin-bottom: var(--space-6);
    text-align: center;
    letter-spacing: -0.025em;
}

h2 {
    font-size: var(--font-size-3xl);
    font-weight: var(--font-weight-semibold);
    line-height: var(--line-height-tight);
    color: var(--text-primary);
    margin-bottom: var(--space-8);
    text-align: center;
}

h3 {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-semibold);
    line-height: var(--line-height-normal);
    color: var(--text-primary);
    margin-bottom: var(--space-4);
}

h4 {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-medium);
    color: var(--text-primary);
    margin-bottom: var(--space-3);
}

p {
    margin-bottom: var(--space-4);
    color: var(--text-secondary);
    line-height: var(--line-height-relaxed);
    font-size: var(--font-size-lg);
}

/* Enhanced Structured Navigation System */
.main-header {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid rgba(79, 70, 229, 0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.main-nav {
    position: relative;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-4);
    display: flex;
    align-items: center;
    justify-content: space-between;
    min-height: 64px;
}

.nav-brand .brand-link {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    text-decoration: none;
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    color: var(--primary-blue);
    transition: all 0.3s ease;
}

.nav-brand .brand-link:hover {
    transform: scale(1.05);
    color: var(--secondary-indigo);
}

.brand-text {
    background: linear-gradient(135deg, #4F46E5 0%, #3B82F6 100%);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

/* Desktop Navigation */
.desktop-nav {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
    gap: var(--space-2);
}

.desktop-nav .nav-link {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-4);
    border-radius: var(--border-radius-lg);
    text-decoration: none;
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    color: var(--text-secondary);
    transition: all 0.3s ease;
    position: relative;
    white-space: nowrap;
}

.desktop-nav .nav-link:hover {
    background: rgba(79, 70, 229, 0.1);
    color: var(--primary-blue);
    transform: translateY(-1px);
}

.desktop-nav .nav-link.active {
    background: linear-gradient(135deg, #4F46E5 0%, #3B82F6 100%);
    color: var(--text-inverse);
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.3);
}

.nav-icon {
    font-size: var(--font-size-lg);
    line-height: 1;
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    width: 44px;
    height: 44px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--space-2);
    border-radius: var(--border-radius-md);
    transition: all 0.3s ease;
}

.mobile-menu-toggle:hover {
    background: rgba(79, 70, 229, 0.1);
}

.hamburger-line {
    width: 24px;
    height: 2px;
    background: var(--primary-blue);
    margin: 2px 0;
    transition: all 0.3s ease;
    border-radius: 1px;
}

.mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -6px);
}

/* Mobile Navigation */
.mobile-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--surface-white);
    border-top: 1px solid rgba(79, 70, 229, 0.1);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
    transform: translateY(-10px);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    max-height: 0;
    overflow: hidden;
}

.mobile-nav.show {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
    max-height: 400px;
}

.mobile-nav-menu {
    list-style: none;
    margin: 0;
    padding: var(--space-4);
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.mobile-nav-link {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-4);
    border-radius: var(--border-radius-lg);
    text-decoration: none;
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    color: var(--text-secondary);
    transition: all 0.3s ease;
    border: 1px solid transparent;
}

.mobile-nav-link:hover,
.mobile-nav-link.active {
    background: linear-gradient(135deg, #4F46E5 0%, #3B82F6 100%);
    color: var(--text-inverse);
    border-color: rgba(79, 70, 229, 0.2);
    box-shadow: 0 2px 8px rgba(79, 70, 229, 0.2);
}

/* Reading Progress Bar */
.progress-bar-container {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: rgba(79, 70, 229, 0.1);
}

.progress-bar {
    height: 100%;
    background: linear-gradient(90deg, #4F46E5 0%, #3B82F6 100%);
    width: 0;
    transition: width 0.3s ease;
}

/* Table of Contents Sidebar */
.table-of-contents {
    position: fixed;
    top: 64px;
    right: -320px;
    width: 300px;
    height: calc(100vh - 64px);
    background: var(--surface-white);
    border-left: 1px solid rgba(79, 70, 229, 0.1);
    box-shadow: -4px 0 16px rgba(0, 0, 0, 0.1);
    z-index: 900;
    transition: all 0.3s ease;
    overflow-y: auto;
}

.table-of-contents.show {
    right: 0;
}

.toc-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-4);
    border-bottom: 1px solid rgba(79, 70, 229, 0.1);
    background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
}

.toc-header h3 {
    margin: 0;
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    color: var(--text-primary);
}

.toc-close {
    background: none;
    border: none;
    font-size: var(--font-size-xl);
    color: var(--text-secondary);
    cursor: pointer;
    padding: var(--space-2);
    border-radius: var(--border-radius-md);
    transition: all 0.3s ease;
}

.toc-close:hover {
    background: rgba(79, 70, 229, 0.1);
    color: var(--primary-blue);
}

.toc-nav {
    padding: var(--space-4);
}

.toc-list {
    list-style: none;
    margin: 0;
    padding: 0;
}

.toc-list li {
    margin-bottom: var(--space-2);
}

.toc-link {
    display: block;
    padding: var(--space-3) var(--space-4);
    border-radius: var(--border-radius-md);
    text-decoration: none;
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    color: var(--text-secondary);
    transition: all 0.3s ease;
    border-left: 3px solid transparent;
}

.toc-link:hover,
.toc-link.active {
    background: rgba(79, 70, 229, 0.1);
    color: var(--primary-blue);
    border-left-color: var(--primary-blue);
    transform: translateX(4px);
}

.toc-sublist {
    list-style: none;
    margin: var(--space-2) 0 0 var(--space-4);
    padding: 0;
}

.toc-sublink {
    display: block;
    padding: var(--space-2) var(--space-3);
    border-radius: var(--border-radius-sm);
    text-decoration: none;
    font-size: var(--font-size-xs);
    color: var(--text-tertiary);
    transition: all 0.3s ease;
}

.toc-sublink:hover,
.toc-sublink.active {
    background: rgba(79, 70, 229, 0.05);
    color: var(--primary-blue);
}

/* Floating Action Buttons */
.floating-actions {
    position: fixed;
    bottom: var(--space-6);
    right: var(--space-6);
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
    z-index: 800;
}

.fab {
    width: 56px;
    height: 56px;
    border-radius: 50%;
    border: none;
    background: linear-gradient(135deg, #4F46E5 0%, #3B82F6 100%);
    color: var(--text-inverse);
    font-size: var(--font-size-xl);
    cursor: pointer;
    box-shadow: 0 4px 16px rgba(79, 70, 229, 0.3);
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.fab:hover {
    transform: translateY(-2px) scale(1.1);
    box-shadow: 0 6px 24px rgba(79, 70, 229, 0.4);
}

.fab:active {
    transform: scale(0.95);
}

/* Main Content Adjustments */
.main-content {
    padding-top: 0;
    transition: margin-right 0.3s ease;
}

.main-content.toc-open {
    margin-right: 320px;
}

/* Responsive Design */
@media (max-width: 968px) {
    .desktop-nav {
        display: none;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .table-of-contents {
        width: 100%;
        right: -100%;
    }
    
    .table-of-contents.show {
        right: 0;
    }
    
    .main-content.toc-open {
        margin-right: 0;
    }
    
    .floating-actions {
        bottom: var(--space-4);
        right: var(--space-4);
    }
    
    .fab {
        width: 48px;
        height: 48px;
        font-size: var(--font-size-lg);
    }
}

@media (max-width: 480px) {
    .nav-container {
        padding: 0 var(--space-3);
    }
    
    .nav-brand .brand-link {
        font-size: var(--font-size-lg);
    }
    
    .floating-actions {
        bottom: var(--space-3);
        right: var(--space-3);
        gap: var(--space-2);
    }
    
    .fab {
        width: 44px;
        height: 44px;
        font-size: var(--font-size-base);
    }
}

/* Hero Section - Blue gradient design */
.hero {
    background: linear-gradient(135deg, #4F46E5 0%, #3B82F6 50%, #1D4ED8 100%);
    padding: var(--space-8) 0 var(--space-12);
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero .container {
    position: relative;
    z-index: 1;
}

.hero h1 {
    color: var(--text-inverse);
    font-size: var(--font-size-5xl);
    font-weight: var(--font-weight-bold);
    margin-bottom: var(--space-6);
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.hero-description {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-normal);
    line-height: var(--line-height-relaxed);
    color: rgba(255, 255, 255, 0.9);
    max-width: 600px;
    margin: 0 auto;
}

/* Converter Section - Centered design like the image */
.converter-section {
    padding: var(--space-6) 0 var(--space-8);
    background: var(--surface-light);
    min-height: 50vh;
    display: flex;
    align-items: flex-start;
    justify-content: center;
}

.converter-card {
    background: var(--surface-card);
    border-radius: 32px;
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.12);
    border: 1px solid rgba(255, 255, 255, 0.8);
    padding: var(--space-8) var(--space-6);
    max-width: 900px;
    width: 100%;
    margin: -var(--space-6) auto 0;
    position: relative;
    z-index: 10;
}

/* Conversion Tabs - Clean segmented control */
.conversion-tabs {
    display: flex;
    background: rgba(107, 114, 128, 0.08);
    border-radius: 16px;
    padding: 4px;
    margin-bottom: var(--space-8);
    position: relative;
    border: 1px solid rgba(107, 114, 128, 0.12);
}

.tab-button {
    flex: 1;
    padding: 12px 24px;
    border: none;
    background: transparent;
    border-radius: 12px;
    font-family: var(--font-family-primary);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-semibold);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    z-index: 2;
    min-height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.tab-button.active {
    background: linear-gradient(135deg, #4F46E5 0%, #3B82F6 100%);
    color: var(--text-inverse);
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.3);
    font-weight: var(--font-weight-bold);
}

.tab-button:hover:not(.active) {
    color: var(--text-primary);
    background: rgba(107, 114, 128, 0.08);
    transform: translateY(-1px);
}

.tab-button:active {
    transform: translateY(0);
    transition: transform 0.1s;
}

/* Converter Form - True horizontal layout */
.converter-form {
    display: flex;
    flex-direction: column;
    gap: var(--space-6);
    align-items: center;
}

.conversion-main {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-8);
    width: 100%;
    max-width: 800px;
}

.input-group,
.result-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-3);
    flex: 1;
    max-width: 280px;
}

.conversion-arrow-container {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    margin: 0 var(--space-4);
    align-self: center;
}

.action-buttons {
    display: flex;
    justify-content: center;
    gap: var(--space-6);
    margin-top: var(--space-6);
    flex-wrap: wrap;
}

.quick-values {
    margin-top: var(--space-8);
    padding-top: var(--space-8);
    border-top: 1px solid rgba(209, 213, 219, 0.3);
    position: relative;
    width: 100%;
}

.input-label, .result-label {
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    color: var(--text-tertiary);
    text-align: center;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--space-2);
}

/* Input Container - Enhanced border design for better visual appeal */
.input-container {
    display: flex;
    align-items: center;
    background: var(--surface-white);
    border: 2px solid rgba(79, 70, 229, 0.15);
    border-radius: 24px;
    padding: var(--space-6) var(--space-5);
    gap: var(--space-3);
    transition: all 0.3s ease;
    position: relative;
    min-height: 80px;
    width: 280px;
    box-shadow: 0 4px 16px rgba(79, 70, 229, 0.08);
}

.input-container:focus-within {
    border-color: #4F46E5;
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1), 0 6px 20px rgba(79, 70, 229, 0.15);
    background: rgba(255, 255, 255, 0.98);
}

.temperature-input {
    flex: 1;
    border: none;
    background: transparent;
    font-family: var(--font-family-primary);
    font-size: var(--font-size-4xl);
    font-weight: var(--font-weight-semibold);
    color: var(--text-primary);
    text-align: center;
    outline: none;
    width: 100%;
}

.temperature-input:focus {
    color: #4F46E5;
}

.temperature-input::placeholder {
    color: var(--gray-400);
    font-weight: var(--font-weight-normal);
}

.input-unit {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    color: var(--text-secondary);
    background: rgba(79, 70, 229, 0.08);
    padding: var(--space-3) var(--space-4);
    border-radius: 12px;
    min-width: 48px;
    text-align: center;
    border: 1px solid rgba(79, 70, 229, 0.1);
}

.input-container:focus-within .input-unit {
    color: #4F46E5;
    background: rgba(79, 70, 229, 0.12);
    border-color: rgba(79, 70, 229, 0.2);
}

/* Conversion Arrow - Redesigned to match the core functionality area */
.conversion-arrow {
    display: flex;
    justify-content: center;
    align-items: center;
    color: var(--text-inverse);
    background: linear-gradient(135deg, #4F46E5 0%, #3B82F6 100%);
    width: 48px;
    height: 48px;
    border-radius: 50%;
    transition: all 0.3s ease;
    cursor: pointer;
    flex-shrink: 0;
    border: none;
    box-shadow: 0 4px 16px rgba(79, 70, 229, 0.3);
}

.conversion-arrow:hover {
    background: linear-gradient(135deg, #3730A3 0%, #1E40AF 100%);
    box-shadow: 0 6px 24px rgba(79, 70, 229, 0.4);
    transform: scale(1.1);
}

.conversion-arrow svg {
    width: 20px;
    height: 20px;
    transform: rotate(-90deg);
}

/* Result Container - Enhanced to match input container styling */
.result-container {
    display: flex;
    align-items: center;
    background: linear-gradient(135deg, #4F46E5 0%, #3B82F6 100%);
    border: 2px solid rgba(79, 70, 229, 0.2);
    border-radius: 24px;
    padding: var(--space-6) var(--space-5);
    gap: var(--space-3);
    transition: all 0.3s ease;
    position: relative;
    min-height: 80px;
    width: 280px;
    box-shadow: 0 6px 24px rgba(79, 70, 229, 0.3);
}

.result-container:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 32px rgba(79, 70, 229, 0.4);
}

.result-value {
    flex: 1;
    font-size: var(--font-size-4xl);
    font-weight: var(--font-weight-bold);
    text-align: center;
    color: var(--text-inverse);
    line-height: 1;
    width: 100%;
}

.result-unit {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    color: var(--text-inverse);
    background: rgba(255, 255, 255, 0.25);
    padding: var(--space-3) var(--space-4);
    border-radius: 12px;
    min-width: 48px;
    text-align: center;
}

/* Action Buttons - Elegant design for horizontal layout */
.btn {
    padding: var(--space-5) var(--space-8);
    border: none;
    border-radius: 16px;
    font-family: var(--font-family-primary);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-semibold);
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: center;
    min-height: 52px;
    min-width: 140px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
}

.btn-clear {
    background: var(--gray-100);
    color: var(--text-secondary);
    border: 1px solid var(--gray-200);
}

.btn-clear:hover {
    background: var(--gray-200);
    color: var(--text-primary);
}

.btn-copy {
    background: linear-gradient(135deg, #4F46E5 0%, #3B82F6 100%);
    color: var(--text-inverse);
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.3);
}

.btn-copy:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(79, 70, 229, 0.4);
}

/* Quick Values - Luxury pill buttons */
.quick-values {
    margin-top: var(--space-16);
    padding-top: var(--space-12);
    border-top: 1px solid rgba(209, 213, 219, 0.3);
    position: relative;
}

.quick-values::before {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--primary-blue), transparent);
}

.quick-values h3 {
    text-align: center;
    margin-bottom: var(--space-6);
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-bold);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    position: relative;
}

.quick-buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--space-5);
    max-width: 600px;
    margin: 0 auto;
}

.quick-btn {
    padding: var(--space-4) var(--space-5);
    border: 1px solid rgba(79, 70, 229, 0.2);
    background: var(--surface-white);
    border-radius: 24px;
    font-family: var(--font-family-primary);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-semibold);
    color: #4F46E5;
    cursor: pointer;
    transition: all 0.3s ease;
    min-height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
}

.quick-btn:hover {
    background: #4F46E5;
    color: var(--text-inverse);
    border-color: #4F46E5;
    transform: translateY(-3px);
    box-shadow: 0 8px 24px rgba(79, 70, 229, 0.25);
}

/* Reference Section - Modern card layout */
.reference-section {
    padding: var(--space-20) 0;
    background: var(--surface-white);
}

.reference-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-6);
    margin-top: var(--space-12);
}

.reference-card {
    background: var(--gradient-surface);
    border: var(--border-light);
    border-radius: var(--border-radius-xl);
    padding: var(--space-8);
    text-align: center;
    transition: var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.reference-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: var(--gradient-primary);
}

.reference-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-blue-100);
}

.reference-card h3 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--space-6);
    color: var(--text-primary);
    font-weight: var(--font-weight-semibold);
}

.temp-values {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-4);
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-bold);
    color: var(--primary-blue);
    font-family: var(--font-family-mono);
}

/* Formula Section - Clean and informative */
.formula-section {
    padding: var(--space-20) 0;
    background: var(--gray-50);
}

.formula-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--space-8);
    margin-top: var(--space-12);
}

.formula-card {
    background: var(--surface-white);
    border: var(--border-light);
    border-radius: var(--border-radius-xl);
    padding: var(--space-10);
    box-shadow: var(--shadow-lg);
    text-align: center;
    transition: var(--transition-normal);
}

.formula-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
}

.formula {
    background: var(--primary-blue-50);
    border: 1px solid var(--primary-blue-100);
    border-radius: var(--border-radius-lg);
    padding: var(--space-6);
    font-family: var(--font-family-mono);
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-semibold);
    color: var(--primary-blue);
    margin: var(--space-6) 0;
    letter-spacing: 0.05em;
}

.formula-description {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    line-height: var(--line-height-relaxed);
}

/* FAQ Section - Improved readability */
.faq-section {
    padding: var(--space-20) 0;
    background: var(--surface-white);
}

.faq-list {
    max-width: 900px;
    margin: var(--space-12) auto 0;
    display: grid;
    gap: var(--space-6);
}

.faq-item {
    background: var(--gradient-surface);
    border: var(--border-light);
    border-radius: var(--border-radius-xl);
    padding: var(--space-8);
    transition: var(--transition-normal);
}

.faq-item:hover {
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-blue-100);
}

.faq-item h3 {
    font-size: var(--font-size-xl);
    color: var(--primary-blue);
    margin-bottom: var(--space-4);
    font-weight: var(--font-weight-semibold);
}

.faq-item p {
    color: var(--text-secondary);
    line-height: var(--line-height-relaxed);
    margin-bottom: 0;
    font-size: var(--font-size-lg);
}

/* Footer - Modern dark theme */
footer {
    background: var(--gray-900);
    color: var(--text-inverse);
    padding: var(--space-20) 0 var(--space-8);
    position: relative;
}

footer::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: var(--gradient-primary);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-12);
    margin-bottom: var(--space-16);
}

.footer-section h4 {
    color: var(--text-inverse);
    margin-bottom: var(--space-6);
    font-weight: var(--font-weight-semibold);
    font-size: var(--font-size-lg);
}

.footer-section p,
.footer-section li {
    color: var(--gray-300);
    font-size: var(--font-size-lg);
    line-height: var(--line-height-relaxed);
}

.footer-section ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.footer-section ul li {
    transition: var(--transition-fast);
}

.footer-section ul li:hover {
    color: var(--text-inverse);
    padding-left: var(--space-2);
}

.footer-bottom {
    border-top: 1px solid var(--gray-700);
    padding-top: var(--space-6);
    text-align: center;
}

.footer-bottom p {
    color: var(--gray-400);
    font-size: var(--font-size-sm);
}

/* Responsive Design - Enhanced mobile experience with horizontal layout */
@media (max-width: 768px) {
    .hero {
        padding: var(--space-12) 0 var(--space-16);
    }
    
    .hero h1 {
        font-size: var(--font-size-3xl);
    }
    
    .hero-description {
        font-size: var(--font-size-base);
    }
    
    .container {
        padding: 0 var(--space-4);
    }
    
    .converter-card {
        padding: var(--space-8);
        margin: -var(--space-12) var(--space-4) 0;
        border-radius: 24px;
        max-width: none;
    }
    
    /* Mobile: Maintain horizontal layout but make it more compact */
    .conversion-main {
        flex-direction: column;
        gap: var(--space-6);
    }
    
    .input-group,
    .result-group {
        width: 100%;
        max-width: none;
    }
    
    .input-container,
    .result-container {
        width: 100%;
        min-height: 70px;
    }
    
    .conversion-arrow-container {
        margin: var(--space-4) 0;
    }
    
    .conversion-arrow {
        width: 44px;
        height: 44px;
    }
    
    .conversion-arrow svg {
        width: 18px;
        height: 18px;
        transform: rotate(0deg);
    }
    
    .temperature-input,
    .result-value {
        font-size: var(--font-size-3xl);
    }
    
    .action-buttons {
        flex-direction: row;
        gap: var(--space-4);
        margin-top: var(--space-8);
    }
    
    .btn {
        min-height: 48px;
        font-size: var(--font-size-base);
        min-width: 120px;
        flex: 1;
    }
    
    .quick-buttons {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-4);
        max-width: none;
    }
    
    .quick-btn {
        min-height: 44px;
        font-size: var(--font-size-sm);
        padding: var(--space-3) var(--space-4);
    }
    
    /* SEO Content Mobile Optimization */
    .guide-grid {
        grid-template-columns: 1fr;
        gap: var(--space-6);
    }
    
    .applications-grid {
        grid-template-columns: 1fr;
        gap: var(--space-6);
    }
    
    .reference-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-4);
    }
    
    .formula-grid {
        grid-template-columns: 1fr;
        gap: var(--space-6);
    }
    
    .tools-grid {
        grid-template-columns: 1fr;
        gap: var(--space-6);
    }
    
    .timeline::before {
        left: 30px;
    }
    
    .timeline-date {
        width: 80px;
        padding: var(--space-2) var(--space-3);
        font-size: var(--font-size-base);
    }
    
    .timeline-content {
        margin-left: var(--space-6);
        padding: var(--space-6);
    }
    
    .comparison-table th,
    .comparison-table td {
        padding: var(--space-3) var(--space-4);
        font-size: var(--font-size-sm);
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: var(--space-8);
        text-align: center;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: var(--space-10) 0 var(--space-12);
    }
    
    .hero h1 {
        font-size: var(--font-size-2xl);
    }
    
    .converter-card {
        padding: var(--space-6);
        margin: -var(--space-8) var(--space-2) 0;
        border-radius: 20px;
    }
    
    .conversion-tabs {
        border-radius: 12px;
        padding: 3px;
    }
    
    .tab-button {
        padding: var(--space-3) var(--space-4);
        font-size: var(--font-size-sm);
        min-height: 44px;
        border-radius: 10px;
    }
    
    .input-container,
    .result-container {
        border-radius: 16px;
        padding: var(--space-4) var(--space-3);
        min-height: 60px;
    }
    
    .temperature-input,
    .result-value {
        font-size: var(--font-size-xl);
    }
    
    .input-unit,
    .result-unit {
        min-width: 40px;
        padding: var(--space-2);
        font-size: var(--font-size-base);
    }
    
    .conversion-arrow {
        width: 52px;
        height: 52px;
    }
    
    .conversion-arrow svg {
        width: 20px;
        height: 20px;
    }
    
    .btn {
        min-height: 44px;
        font-size: var(--font-size-sm);
        padding: var(--space-3) var(--space-6);
        border-radius: 12px;
    }
    
    .quick-btn {
        min-height: 40px;
        font-size: var(--font-size-xs);
        padding: var(--space-2) var(--space-3);
        border-radius: 20px;
    }
    
    .reference-grid {
        grid-template-columns: 1fr;
        gap: var(--space-4);
    }
    
    .reference-card {
        padding: var(--space-6);
    }
    
    .temp-values {
        font-size: var(--font-size-lg);
        gap: var(--space-2);
    }
    
    .timeline-date {
        width: 60px;
        font-size: var(--font-size-sm);
    }
    
    .timeline-content {
        margin-left: var(--space-4);
        padding: var(--space-4);
    }
    
    .comparison-table th,
    .comparison-table td {
        padding: var(--space-2) var(--space-3);
        font-size: var(--font-size-xs);
    }
    
    .batch-controls,
    .range-inputs {
        flex-direction: column;
        align-items: stretch;
    }
    
    .tool-btn {
        width: 100%;
        margin-top: var(--space-2);
    }
}

/* Landscape mobile optimization */
@media (max-width: 768px) and (orientation: landscape) {
    .converter-form {
        display: grid;
        grid-template-columns: 1fr auto 1fr;
        grid-template-rows: auto auto;
        gap: var(--space-4);
        align-items: center;
    }
    
    .conversion-main {
        display: contents;
    }
    
    .input-group {
        grid-column: 1;
        grid-row: 1;
    }
    
    .conversion-arrow-container {
        grid-column: 2;
        grid-row: 1;
        padding: 0 var(--space-2);
    }
    
    .result-group {
        grid-column: 3;
        grid-row: 1;
    }
    
    .action-buttons {
        grid-column: 1 / -1;
        grid-row: 2;
        flex-direction: row;
        justify-content: center;
        margin-top: var(--space-4);
    }
    
    .btn {
        min-width: 120px;
        width: auto;
    }
    
    .conversion-arrow svg {
        transform: rotate(90deg);
    }
    
    .conversion-arrow:hover svg {
        transform: rotate(90deg) scale(1.1);
    }
}

/* High Contrast Mode Support */
@media (prefers-contrast: high) {
    .converter-card {
        border: 3px solid var(--text-primary);
        background: var(--surface-white);
    }
    
    .btn {
        border: 3px solid currentColor;
    }
    
    .input-container,
    .result-container {
        border: 3px solid var(--text-primary);
    }
    
    .conversion-arrow {
        border: 3px solid var(--primary-blue);
        background: var(--surface-white);
    }
}

/* Print Styles */
@media print {
    .converter-section,
    .reference-section {
        background: white !important;
    }
    
    .converter-card {
        box-shadow: none !important;
        border: 1px solid #ccc;
    }
    
    .btn,
    .quick-btn {
        display: none;
    }
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    :root {
        --apple-gray-light: #1C1C1E;
        --apple-gray-medium: #48484A;
        --apple-white: #1C1C1E;
        --apple-gray-dark: #FFFFFF;
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* Enhanced Focus and Accessibility */
.temperature-input:focus,
.btn:focus,
.tab-button:focus,
.quick-btn:focus {
    outline: none;
    box-shadow: 0 0 0 3px rgba(29, 78, 216, 0.1);
    border-color: var(--primary-blue);
}

.tab-button:focus {
    box-shadow: 0 0 0 3px rgba(29, 78, 216, 0.1);
}

/* Loading States */
.btn.loading {
    pointer-events: none;
    opacity: 0.7;
    position: relative;
}

.btn.loading::after {
    content: '';
    position: absolute;
    width: 16px;
    height: 16px;
    margin: auto;
    border: 2px solid transparent;
    border-top-color: currentColor;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Enhanced Hover Effects and Animations */
@media (hover: hover) {
    .converter-card:hover {
        transform: translateY(-8px) scale(1.02);
        box-shadow: 0 48px 96px rgba(0, 0, 0, 0.12), 0 24px 48px rgba(0, 0, 0, 0.06);
    }
    
    .logo:hover {
        transform: scale(1.08);
        filter: drop-shadow(0 4px 8px rgba(29, 78, 216, 0.2));
    }
    
    .thermometer-icon:hover {
        animation: thermometer-pulse 0.6s ease-in-out;
    }
}

/* Advanced Keyframe Animations */
@keyframes thermometer-pulse {
    0%, 100% { 
        transform: scale(1) rotate(0deg);
        filter: drop-shadow(0 2px 4px rgba(29, 78, 216, 0.1));
    }
    25% { 
        transform: scale(1.1) rotate(-2deg);
        filter: drop-shadow(0 4px 8px rgba(29, 78, 216, 0.2));
    }
    75% { 
        transform: scale(1.1) rotate(2deg);
        filter: drop-shadow(0 4px 8px rgba(29, 78, 216, 0.2));
    }
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-10px); }
}

@keyframes glow {
    0%, 100% {
        box-shadow: 0 0 5px rgba(29, 78, 216, 0.2);
    }
    50% {
        box-shadow: 0 0 20px rgba(29, 78, 216, 0.4), 0 0 30px rgba(29, 78, 216, 0.2);
    }
}

/* Floating animation for conversion arrow */
.conversion-arrow {
    animation: float 4s ease-in-out infinite;
}

/* Input animation states */
.temperature-input.animate-input {
    animation: glow 0.4s ease-in-out;
    transform: scale(1.02);
}

/* Success state animations */
.btn.success {
    background: linear-gradient(135deg, var(--accent-emerald) 0%, #059669 100%) !important;
    transform: scale(1.05) !important;
    animation: glow 0.6s ease-in-out;
    border-color: var(--accent-emerald) !important;
}

.btn.success::after {
    content: '✓';
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    font-size: 1.2em;
    animation: none;
    font-weight: bold;
}

/* Enhanced loading animation */
.btn.loading::after {
    content: '';
    position: absolute;
    width: 20px;
    height: 20px;
    border: 2px solid transparent;
    border-top-color: currentColor;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
}

/* Page load animations */
.converter-card {
    animation: slideUpFade 0.8s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards;
}

@keyframes slideUpFade {
    0% {
        opacity: 0;
        transform: translateY(40px) scale(0.95);
    }
    100% {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

/* Stagger animation for quick buttons */
.quick-btn:nth-child(1) { animation-delay: 0.1s; }
.quick-btn:nth-child(2) { animation-delay: 0.2s; }
.quick-btn:nth-child(3) { animation-delay: 0.3s; }
.quick-btn:nth-child(4) { animation-delay: 0.4s; }

.quick-btn {
    animation: slideUpFade 0.6s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards;
    opacity: 0;
    transform: translateY(20px);
}

/* New SEO Content Sections */

/* Temperature Guide Section */
.temperature-guide-section {
    padding: var(--space-20) 0;
    background: var(--surface-white);
}

.guide-content {
    max-width: 1000px;
    margin: 0 auto;
}

.guide-intro {
    text-align: center;
    margin-bottom: var(--space-12);
    font-size: var(--font-size-xl);
    color: var(--text-secondary);
    line-height: var(--line-height-relaxed);
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.guide-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--space-8);
}

.guide-card {
    background: var(--gradient-surface);
    border: var(--border-light);
    border-radius: var(--border-radius-xl);
    padding: var(--space-8);
    transition: var(--transition-normal);
}

.guide-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-blue-100);
}

.guide-card h3 {
    color: var(--primary-blue);
    margin-bottom: var(--space-4);
    font-size: var(--font-size-xl);
}

.guide-card ul {
    list-style: none;
    padding-left: 0;
}

.guide-card li {
    padding: var(--space-2) 0;
    border-bottom: 1px solid var(--gray-200);
    font-weight: var(--font-weight-medium);
    font-size: var(--font-size-base);
}

.guide-card li:last-child {
    border-bottom: none;
}

/* Temperature Applications Section */
.temperature-applications-section {
    padding: var(--space-20) 0;
    background: var(--gray-50);
}

.applications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-6);
    margin-top: var(--space-12);
}

.app-card {
    background: var(--surface-white);
    border-radius: var(--border-radius-xl);
    padding: var(--space-8);
    text-align: center;
    transition: var(--transition-normal);
    border: var(--border-light);
    box-shadow: var(--shadow-sm);
}

.app-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-blue-100);
}

.app-icon {
    font-size: 3rem;
    margin-bottom: var(--space-4);
}

.app-card h3 {
    color: var(--text-primary);
    margin-bottom: var(--space-4);
    font-size: var(--font-size-xl);
}

.app-examples {
    margin-top: var(--space-6);
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.example {
    background: var(--primary-blue-50);
    color: var(--primary-blue);
    padding: var(--space-3) var(--space-4);
    border-radius: var(--border-radius-md);
    font-family: var(--font-family-mono);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
}

/* Reference Section - Enhanced */
.reference-intro {
    text-align: center;
    margin-bottom: var(--space-12);
    font-size: var(--font-size-xl);
    color: var(--text-secondary);
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
    line-height: var(--line-height-relaxed);
}

.temp-description {
    font-size: var(--font-size-base);
    color: var(--text-tertiary);
    margin-top: var(--space-3);
    text-align: center;
    font-style: italic;
}

/* Historical Section */
.historical-section {
    padding: var(--space-20) 0;
    background: var(--surface-white);
}

.timeline {
    max-width: 800px;
    margin: var(--space-12) auto 0;
    position: relative;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 60px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--primary-blue);
}

.timeline-item {
    display: flex;
    margin-bottom: var(--space-12);
    position: relative;
}

.timeline-date {
    flex-shrink: 0;
    width: 120px;
    background: var(--primary-blue);
    color: var(--text-inverse);
    padding: var(--space-4);
    border-radius: var(--border-radius-lg);
    text-align: center;
    font-weight: var(--font-weight-bold);
    font-size: var(--font-size-lg);
    position: relative;
    z-index: 2;
}

.timeline-date::after {
    content: '';
    position: absolute;
    right: -10px;
    top: 50%;
    transform: translateY(-50%);
    width: 20px;
    height: 20px;
    background: var(--primary-blue);
    border-radius: 50%;
    border: 4px solid var(--surface-white);
}

.timeline-content {
    flex: 1;
    margin-left: var(--space-8);
    background: var(--gradient-surface);
    padding: var(--space-8);
    border-radius: var(--border-radius-xl);
    border: var(--border-light);
    box-shadow: var(--shadow-sm);
}

.timeline-content h3 {
    color: var(--primary-blue);
    margin-bottom: var(--space-4);
    font-size: var(--font-size-xl);
}

/* Comparison Table Section */
.comparison-table-section {
    padding: var(--space-20) 0;
    background: var(--gray-50);
}

.table-intro {
    text-align: center;
    margin-bottom: var(--space-12);
    font-size: var(--font-size-xl);
    color: var(--text-secondary);
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
    line-height: var(--line-height-relaxed);
}

.comparison-table-container {
    overflow-x: auto;
    background: var(--surface-white);
    border-radius: var(--border-radius-xl);
    box-shadow: var(--shadow-lg);
    border: var(--border-light);
}

.comparison-table {
    width: 100%;
    border-collapse: collapse;
    font-family: var(--font-family-primary);
}

.comparison-table th {
    background: var(--gradient-primary);
    color: var(--text-inverse);
    padding: var(--space-6);
    text-align: left;
    font-weight: var(--font-weight-bold);
    font-size: var(--font-size-lg);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.comparison-table td {
    padding: var(--space-5) var(--space-6);
    border-bottom: 1px solid var(--gray-200);
    font-size: var(--font-size-lg);
    transition: var(--transition-fast);
}

.comparison-table tr:hover td {
    background: var(--primary-blue-50);
}

.comparison-table td:first-child,
.comparison-table td:nth-child(2) {
    font-family: var(--font-family-mono);
    font-weight: var(--font-weight-bold);
    color: var(--primary-blue);
    font-size: var(--font-size-xl);
}

.comparison-table td:last-child {
    color: var(--text-secondary);
    font-style: italic;
}

/* Advanced Tools Section - Enhanced elegant layout */
.conversion-calculator-section {
    padding: var(--space-20) 0;
    background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
    border-top: 1px solid rgba(79, 70, 229, 0.1);
}

.section-intro {
    text-align: center;
    font-size: var(--font-size-xl);
    color: var(--text-secondary);
    max-width: 700px;
    margin: 0 auto var(--space-12);
    line-height: var(--line-height-relaxed);
}

.tools-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-10);
    max-width: 1000px;
    margin: 0 auto;
}

.tool-card {
    background: var(--surface-white);
    border: 2px solid rgba(79, 70, 229, 0.08);
    border-radius: var(--border-radius-2xl);
    padding: var(--space-8);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.06);
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.tool-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(135deg, #4F46E5 0%, #3B82F6 100%);
}

.tool-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 48px rgba(0, 0, 0, 0.12);
    border-color: rgba(79, 70, 229, 0.15);
}

.tool-header {
    display: flex;
    align-items: flex-start;
    gap: var(--space-4);
    margin-bottom: var(--space-8);
}

.tool-icon {
    font-size: 2.5rem;
    line-height: 1;
    background: linear-gradient(135deg, #4F46E5 0%, #3B82F6 100%);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    flex-shrink: 0;
}

.tool-info h3 {
    color: var(--text-primary);
    margin-bottom: var(--space-3);
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-semibold);
}

.tool-info p {
    color: var(--text-secondary);
    font-size: var(--font-size-base);
    line-height: var(--line-height-relaxed);
    margin: 0;
}

/* Enhanced form styling */
.batch-converter,
.range-converter {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-8);
    align-items: start;
}

.input-section,
.results-section {
    display: flex;
    flex-direction: column;
    gap: var(--space-4);
}

.tool-label {
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    color: var(--text-primary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--space-2);
}

.batch-converter textarea {
    width: 100%;
    min-height: 120px;
    padding: var(--space-4);
    border: 2px solid rgba(79, 70, 229, 0.1);
    border-radius: var(--border-radius-lg);
    font-family: var(--font-family-mono);
    font-size: var(--font-size-base);
    line-height: 1.5;
    background: var(--surface-white);
    transition: all 0.3s ease;
    resize: vertical;
}

.batch-converter textarea:focus {
    border-color: #4F46E5;
    outline: none;
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
    background: rgba(255, 255, 255, 0.98);
}

.batch-controls {
    display: flex;
    gap: var(--space-4);
    align-items: center;
    flex-wrap: wrap;
}

.tool-select {
    flex: 1;
    min-width: 160px;
    padding: var(--space-3) var(--space-4);
    border: 2px solid rgba(79, 70, 229, 0.1);
    border-radius: var(--border-radius-md);
    font-family: var(--font-family-primary);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    color: var(--text-primary);
    background: var(--surface-white);
    transition: all 0.3s ease;
}

.tool-select:focus {
    border-color: #4F46E5;
    outline: none;
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.tool-btn {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    background: linear-gradient(135deg, #4F46E5 0%, #3B82F6 100%);
    color: var(--text-inverse);
    border: none;
    padding: var(--space-4) var(--space-6);
    border-radius: var(--border-radius-lg);
    font-family: var(--font-family-primary);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-semibold);
    cursor: pointer;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    min-height: 48px;
    white-space: nowrap;
}

.tool-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(79, 70, 229, 0.3);
    background: linear-gradient(135deg, #3730A3 0%, #1E40AF 100%);
}

.btn-icon {
    font-size: var(--font-size-lg);
    line-height: 1;
}

/* Range inputs styling */
.range-inputs {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    flex-wrap: wrap;
}

.range-input {
    flex: 1;
    min-width: 100px;
    padding: var(--space-3) var(--space-4);
    border: 2px solid rgba(79, 70, 229, 0.1);
    border-radius: var(--border-radius-md);
    font-family: var(--font-family-primary);
    font-size: var(--font-size-base);
    transition: all 0.3s ease;
}

.range-input:focus {
    border-color: #4F46E5;
    outline: none;
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.range-separator {
    font-weight: var(--font-weight-semibold);
    color: var(--text-tertiary);
    white-space: nowrap;
}

/* Results styling */
.batch-results,
.range-result {
    background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
    border: 2px solid rgba(79, 70, 229, 0.08);
    border-radius: var(--border-radius-lg);
    padding: var(--space-6);
    min-height: 120px;
    font-family: var(--font-family-mono);
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    white-space: pre-line;
    overflow-y: auto;
    line-height: 1.6;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.batch-results:empty::before,
.range-result:empty::before {
    content: attr(data-placeholder);
    color: var(--text-tertiary);
    font-style: italic;
}

/* Mobile responsive adjustments */
@media (max-width: 768px) {
    .tools-grid {
        gap: var(--space-8);
    }
    
    .batch-converter,
    .range-converter {
        grid-template-columns: 1fr;
        gap: var(--space-6);
    }
    
    .tool-header {
        flex-direction: column;
        align-items: center;
        text-align: center;
        gap: var(--space-3);
    }
    
    .batch-controls {
        flex-direction: column;
        align-items: stretch;
    }
    
    .tool-select {
        min-width: auto;
    }
    
    .range-inputs {
        flex-direction: column;
        align-items: stretch;
    }
    
    .range-separator {
        text-align: center;
        margin: var(--space-2) 0;
    }
    
    .tool-btn {
        width: 100%;
        justify-content: center;
    }
}
@media (prefers-contrast: high) {
    .converter-card {
        border: 2px solid var(--text-primary);
    }
    
    .btn {
        border: 2px solid currentColor;
    }
    
    .input-container,
    .result-container {
        border: 2px solid var(--text-primary);
    }
}