/* ============================================
   EVM Education Site - Style Sheet
   Based on mat-sim/calculators design system
   ============================================ */

/* ============================================
   1. CSS Variables (Design Tokens)
   ============================================ */
:root {
    /* Primary - EVM Blue */
    --color-primary: #3B82F6;
    --color-primary-dark: #2563EB;
    --color-primary-light: #60A5FA;
    --color-primary-bg: #EFF6FF;

    /* Secondary - Green (Success) */
    --color-secondary: #10B981;
    --color-secondary-dark: #059669;
    --color-secondary-light: #34D399;

    /* Accent - Red (Warning/Highlight) */
    --color-accent: #EF4444;
    --color-accent-dark: #DC2626;
    --color-accent-light: #F87171;

    /* Neutrals */
    --color-gray-50: #F9FAFB;
    --color-gray-100: #F3F4F6;
    --color-gray-200: #E5E7EB;
    --color-gray-300: #D1D5DB;
    --color-gray-400: #9CA3AF;
    --color-gray-500: #6B7280;
    --color-gray-600: #4B5563;
    --color-gray-700: #374151;
    --color-gray-800: #1F2937;
    --color-gray-900: #111827;

    /* Background */
    --color-bg: #FFFFFF;
    --color-bg-secondary: var(--color-gray-50);
    --color-bg-tertiary: var(--color-gray-100);

    /* Text */
    --color-text: var(--color-gray-900);
    --color-text-secondary: var(--color-gray-600);
    --color-text-muted: var(--color-gray-400);

    /* Typography */
    --font-sans: 'Inter', 'Noto Sans JP', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, 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-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 */
    --spacing-1: 0.25rem;
    --spacing-2: 0.5rem;
    --spacing-3: 0.75rem;
    --spacing-4: 1rem;
    --spacing-5: 1.25rem;
    --spacing-6: 1.5rem;
    --spacing-8: 2rem;
    --spacing-10: 2.5rem;
    --spacing-12: 3rem;
    --spacing-16: 4rem;
    --spacing-20: 5rem;

    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-full: 9999px;

    /* Shadows */
    --shadow-sm: 0 1px 2px 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);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 200ms ease;
    --transition-slow: 300ms ease;

    /* Container */
    --container-max: 1200px;
    --container-padding: var(--spacing-6);
}

/* ============================================
   2. Reset & Base Styles
   ============================================ */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

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

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

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--color-primary-dark);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

ul, ol {
    list-style: none;
}

/* ============================================
   3. Layout
   ============================================ */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

.section {
    padding: var(--spacing-16) 0;
}

.section:nth-child(even) {
    background-color: var(--color-bg-secondary);
}

/* ============================================
   4. Header
   ============================================ */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-gray-200);
    box-shadow: var(--shadow-sm);
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    color: var(--color-text);
    font-weight: var(--font-weight-semibold);
    font-size: var(--font-size-lg);
}

.logo:hover {
    color: var(--color-primary);
}

.logo-icon {
    display: flex;
    color: var(--color-primary);
}

.main-nav ul {
    display: flex;
    gap: var(--spacing-6);
}

.main-nav a {
    color: var(--color-text-secondary);
    font-weight: var(--font-weight-medium);
    padding: var(--spacing-2) 0;
    position: relative;
}

.main-nav a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--color-primary);
    transition: width var(--transition-normal);
}

.main-nav a:hover {
    color: var(--color-primary);
}

.main-nav a:hover::after {
    width: 100%;
}

/* ============================================
   5. Hero Section
   ============================================ */
.hero {
    padding: var(--spacing-16) 0 var(--spacing-20);
    background: linear-gradient(180deg, var(--color-primary-bg) 0%, var(--color-bg) 100%);
}

.hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-12);
    align-items: center;
}

.hero h1 {
    font-size: var(--font-size-4xl);
    font-weight: var(--font-weight-bold);
    line-height: var(--line-height-tight);
    color: var(--color-text);
    margin-bottom: var(--spacing-6);
}

.hero h1 .highlight {
    color: var(--color-primary);
}

.hero-subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-8);
    line-height: var(--line-height-relaxed);
}

.hero-actions {
    display: flex;
    gap: var(--spacing-4);
}

/* Demo Preview */
.demo-preview {
    background-color: var(--color-bg);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
    aspect-ratio: 16/10;
}

.demo-placeholder {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    background-color: var(--color-gray-100);
    color: var(--color-text-secondary);
}

.pulse-icon {
    width: 80px;
    height: 80px;
    border-radius: var(--radius-full);
    background-color: var(--color-primary-light);
    animation: pulse 2s infinite;
    margin-bottom: var(--spacing-4);
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
        opacity: 1;
    }
    50% {
        transform: scale(1.1);
        opacity: 0.7;
    }
}

/* ============================================
   6. Buttons
   ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-2);
    padding: var(--spacing-3) var(--spacing-6);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    border-radius: var(--radius-md);
    border: 2px solid transparent;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.btn-primary {
    background-color: var(--color-primary);
    color: white;
}

.btn-primary:hover {
    background-color: var(--color-primary-dark);
    color: white;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: transparent;
    color: var(--color-primary);
    border-color: var(--color-primary);
}

.btn-secondary:hover {
    background-color: var(--color-primary-bg);
    color: var(--color-primary-dark);
}

/* ============================================
   7. Section Titles
   ============================================ */
.section-title {
    font-size: var(--font-size-3xl);
    font-weight: var(--font-weight-bold);
    color: var(--color-text);
    margin-bottom: var(--spacing-4);
    text-align: center;
}

.section-description {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    text-align: center;
    max-width: 600px;
    margin: 0 auto var(--spacing-12);
}

/* ============================================
   8. Cards
   ============================================ */
.card-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-6);
}

.card-grid-3 {
    grid-template-columns: repeat(3, 1fr);
}

.card {
    display: flex;
    align-items: center;
    gap: var(--spacing-4);
    padding: var(--spacing-6);
    background-color: var(--color-bg);
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-gray-200);
    color: var(--color-text);
    transition: all var(--transition-normal);
}

.card:hover {
    border-color: var(--color-primary-light);
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
    color: var(--color-text);
}

.card-highlight {
    border-color: var(--color-primary);
    background: linear-gradient(135deg, var(--color-primary-bg) 0%, var(--color-bg) 100%);
}

.card-icon {
    flex-shrink: 0;
    width: 64px;
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--color-primary-bg);
    border-radius: var(--radius-lg);
    color: var(--color-primary);
}

.card-content {
    flex: 1;
}

.card-title {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-2);
}

.card-description {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.card-arrow {
    flex-shrink: 0;
    color: var(--color-gray-400);
    transition: transform var(--transition-fast);
}

.card:hover .card-arrow {
    color: var(--color-primary);
    transform: translateX(4px);
}

/* ============================================
   9. Footer
   ============================================ */
.site-footer {
    background-color: var(--color-gray-900);
    color: var(--color-gray-300);
    padding: var(--spacing-12) 0 var(--spacing-6);
}

.footer-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: var(--spacing-12);
    margin-bottom: var(--spacing-8);
}

.footer-logo {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-semibold);
    color: white;
    margin-bottom: var(--spacing-2);
}

.footer-description {
    font-size: var(--font-size-sm);
    line-height: var(--line-height-relaxed);
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-8);
}

.footer-column h4 {
    color: white;
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--spacing-4);
}

.footer-column ul {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-2);
}

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

.footer-column a:hover {
    color: white;
}

.footer-bottom {
    padding-top: var(--spacing-6);
    border-top: 1px solid var(--color-gray-700);
}

.copyright {
    font-size: var(--font-size-xs);
    color: var(--color-gray-500);
    text-align: center;
}

/* ============================================
   10. Responsive Design
   ============================================ */
@media (max-width: 1024px) {
    .card-grid-3 {
        grid-template-columns: repeat(2, 1fr);
    }

    .hero .container {
        grid-template-columns: 1fr;
    }

    .hero-visual {
        order: -1;
    }
}

@media (max-width: 768px) {
    :root {
        --container-padding: var(--spacing-4);
    }

    .main-nav {
        display: none;
    }

    .hero h1 {
        font-size: var(--font-size-3xl);
    }

    .hero-subtitle {
        font-size: var(--font-size-base);
    }

    .hero-subtitle br {
        display: none;
    }

    .hero-actions {
        flex-direction: column;
    }

    .section {
        padding: var(--spacing-12) 0;
    }

    .section-title {
        font-size: var(--font-size-2xl);
    }

    .card-grid,
    .card-grid-3 {
        grid-template-columns: 1fr;
    }

    .footer-content {
        grid-template-columns: 1fr;
    }

    .footer-links {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 480px) {
    .card {
        flex-direction: column;
        text-align: center;
    }

    .card-arrow {
        display: none;
    }

    .footer-links {
        grid-template-columns: 1fr;
    }
}