/* ============================================
   CSS VARIABLES (Design Tokens)
   ============================================ */
:root {
    /* Color Palette */
    --color-primary: #667eea;
    --color-secondary: #764ba2;
    --color-success: #48bb78;
    --color-danger: #f56565;
    --color-background: #edf2f7;
    --color-text-primary: #1a202c;
    --color-text-secondary: #2d3748;
    --color-text-body: #4a5568;
    --color-text-muted: #718096;
    --color-border: #e2e8f0;
    --color-code-bg: #f7fafc;
    --color-white: #ffffff;
    
    /* Spacing Scale */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    --spacing-xxl: 48px;
    
    /* Typography */
    --font-primary: 'Inter', sans-serif;
    --font-heading: 'Playfair Display', serif;
    --font-code: 'Fira Code', monospace;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 20px;
    
    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.1);
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
}


/* ============================================
   RESET & BASE STYLES
   ============================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-primary);
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    color: var(--color-text-secondary);
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-xxl) var(--spacing-lg);
}


/* ============================================
   HEADER
   ============================================ */
header {
    text-align: center;
    margin-bottom: var(--spacing-xxl);
    padding: var(--spacing-xxl) 0;
    background: var(--color-white);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
}

header h1 {
    font-family: var(--font-heading);
    font-size: 3.5rem;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-sm);
}

header p {
    font-size: 1.2rem;
    color: var(--color-text-muted);
}


/* ============================================
   NAVIGATION
   ============================================ */
.navigation {
    background: var(--color-white);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-xxl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
}

.navigation__list {
    list-style: none;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.navigation__item {
    margin: 0;
}

.navigation__link {
    font-family: var(--font-primary);
    font-weight: 500;
    color: var(--color-text-body);
    text-decoration: none;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
    display: inline-block;
}

.navigation__link:hover,
.navigation__link:focus {
    color: var(--color-primary);
    background-color: var(--color-background);
    transform: translateY(-2px);
}


/* ============================================
   SECTIONS
   ============================================ */
section {
    background: var(--color-white);
    padding: var(--spacing-xxl);
    margin-bottom: var(--spacing-xxl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
}

h2 {
    font-family: var(--font-heading);
    font-size: 2.5rem;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 3px solid var(--color-primary);
}

h3 {
    font-size: 1.5rem;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-md);
    font-weight: 600;
}

.section-description {
    font-size: 1.05rem;
    color: var(--color-text-body);
    line-height: 1.7;
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-lg);
    background: var(--color-background);
    border-radius: var(--radius-lg);
    border-left: 4px solid var(--color-primary);
}


/* ============================================
   COLOR PALETTE
   ============================================ */
.color-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-xl);
}

.color-card {
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.color-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.15);
}

.color-display {
    height: 150px;
    width: 100%;
}

/* Color Display Variants */
.color-display--primary { background-color: var(--color-primary); }
.color-display--secondary { background-color: var(--color-secondary); }
.color-display--success { background-color: var(--color-success); }
.color-display--danger { background-color: var(--color-danger); }
.color-display--light { background-color: var(--color-background); }
.color-display--dark { background-color: var(--color-text-primary); }

.color-info {
    padding: var(--spacing-lg);
}

.color-name {
    font-weight: 600;
    font-size: 1.2rem;
    margin-bottom: var(--spacing-sm);
    color: var(--color-text-primary);
}

.color-value {
    font-family: var(--font-code);
    background: var(--color-code-bg);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    margin-bottom: var(--spacing-sm);
    display: inline-block;
    color: var(--color-text-body);
}

.color-description {
    color: var(--color-text-muted);
    font-size: 0.95rem;
    line-height: 1.5;
}


/* ============================================
   TYPOGRAPHY / FONTS
   ============================================ */
.font-showcase {
    margin-bottom: var(--spacing-xxl);
    padding: var(--spacing-xl);
    background: var(--color-code-bg);
    border-radius: var(--radius-lg);
    border-left: 4px solid var(--color-primary);
}

.font-showcase:last-child {
    margin-bottom: 0;
}

.font-name {
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    color: var(--color-text-primary);
}

.font-usage {
    color: var(--color-text-muted);
    font-style: italic;
    margin-bottom: var(--spacing-lg);
}

.font-example {
    margin-bottom: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--color-white);
    border-radius: var(--radius-md);
}

.font-example:last-child {
    margin-bottom: 0;
}

.font-label {
    font-size: 0.85rem;
    color: var(--color-text-muted);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: var(--spacing-sm);
}

.font-demo {
    font-size: 1.3rem;
}


/* ============================================
   TEXT STYLES
   ============================================ */
.typography-example {
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-lg);
    background: var(--color-code-bg);
    border-radius: var(--radius-lg);
    border-left: 4px solid var(--color-success);
}

.typography-example:last-child {
    margin-bottom: 0;
}

.element-name {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: var(--spacing-sm);
}

.element-usage {
    color: var(--color-text-muted);
    font-style: italic;
    margin-bottom: var(--spacing-md);
    font-size: 0.95rem;
}

.style-rules {
    font-family: var(--font-code);
    background: var(--color-white);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: 0.85rem;
    color: var(--color-text-body);
    margin: var(--spacing-sm) 0;
    border: 1px solid var(--color-border);
    white-space: pre-line;
}

.style-preview {
    margin-top: var(--spacing-md);
    padding: var(--spacing-lg);
    background: var(--color-white);
    border-radius: var(--radius-md);
    border: 2px dashed var(--color-border);
}

/* Text Style Previews */
.style-h1 {
    font-family: var(--font-heading);
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--color-text-primary);
    line-height: 1.2;
}

.style-h2 {
    font-family: var(--font-heading);
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--color-text-primary);
    line-height: 1.3;
    border-bottom: 3px solid var(--color-primary);
    padding-bottom: var(--spacing-sm);
}

.style-h3 {
    font-family: var(--font-primary);
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--color-text-secondary);
    line-height: 1.4;
}

.style-paragraph {
    font-family: var(--font-primary);
    font-size: 1rem;
    font-weight: 400;
    color: var(--color-text-body);
    line-height: 1.6;
}

.style-link {
    font-family: var(--font-primary);
    font-weight: 500;
    color: var(--color-primary);
    text-decoration: underline;
    transition: color var(--transition-base);
}

.style-link:hover,
.style-link:focus {
    color: var(--color-secondary);
}

.style-code {
    font-family: var(--font-code);
    font-size: 0.9rem;
    background-color: var(--color-code-bg);
    padding: 2px 6px;
    border-radius: var(--radius-sm);
    color: var(--color-danger);
}


/* ============================================
   BUTTONS
   ============================================ */
.button-showcase {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-xl);
}

.button-example {
    padding: var(--spacing-lg);
    background: var(--color-code-bg);
    border-radius: var(--radius-lg);
    border-left: 4px solid var(--color-secondary);
    text-align: center;
}

/* Base Button Styles */
.btn {
    font-family: var(--font-primary);
    padding: 12px 24px;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 1rem;
    border: none;
    cursor: pointer;
    transition: all var(--transition-base);
    margin: var(--spacing-md) 0;
    display: inline-block;
}

/* Button Variants */
.btn--primary {
    background-color: var(--color-primary);
    color: var(--color-white);
}

.btn--primary:hover,
.btn--primary:focus {
    background-color: #5568d3;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.btn--secondary {
    background-color: transparent;
    color: var(--color-primary);
    border: 2px solid var(--color-primary);
}

.btn--secondary:hover,
.btn--secondary:focus {
    background-color: var(--color-primary);
    color: var(--color-white);
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

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

.btn--success:hover,
.btn--success:focus {
    background-color: #38a169;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(72, 187, 120, 0.4);
}

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

.btn--danger:hover,
.btn--danger:focus {
    background-color: #e53e3e;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(245, 101, 101, 0.4);
}


/* ============================================
   SPACING & LAYOUT
   ============================================ */
.spacing-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-xl);
}

.spacing-item {
    padding: var(--spacing-lg);
    background: var(--color-code-bg);
    border-radius: var(--radius-lg);
    border-left: 4px solid var(--color-success);
}

.spacing-visual {
    background-color: var(--color-primary);
    border-radius: var(--radius-sm);
    margin-bottom: var(--spacing-md);
    height: 40px;
}

/* Spacing Visual Variants */
.spacing-visual--xs { width: var(--spacing-xs); }
.spacing-visual--sm { width: var(--spacing-sm); }
.spacing-visual--md { width: var(--spacing-md); }
.spacing-visual--lg { width: var(--spacing-lg); }
.spacing-visual--xl { width: var(--spacing-xl); }
.spacing-visual--xxl { width: var(--spacing-xxl); }

.spacing-info {
    background: var(--color-white);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
}

.spacing-name {
    font-weight: 600;
    font-size: 1.1rem;
    margin-bottom: var(--spacing-xs);
    color: var(--color-text-primary);
}

.spacing-value {
    font-family: var(--font-code);
    background: var(--color-code-bg);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    margin-bottom: var(--spacing-sm);
    display: inline-block;
    color: var(--color-text-body);
}

.spacing-usage {
    color: var(--color-text-muted);
    font-size: 0.9rem;
    line-height: 1.5;
}


/* ============================================
   FOOTER
   ============================================ */
.footer {
    text-align: center;
    padding: var(--spacing-xl) 0;
    color: var(--color-text-muted);
    font-size: 0.9rem;
}


/* ============================================
   RESPONSIVE DESIGN
   ============================================ */

/* Tablets and smaller */
@media (max-width: 768px) {
    header h1 {
        font-size: 2.5rem;
    }
    
    h2 {
        font-size: 2rem;
    }
    
    .style-h1 {
        font-size: 2.5rem;
    }
    
    .style-h2 {
        font-size: 2rem;
    }
    
    .navigation__list {
        flex-direction: column;
        align-items: center;
    }
    
    .color-grid,
    .button-showcase,
    .spacing-grid {
        grid-template-columns: 1fr;
    }
    
    section {
        padding: var(--spacing-lg);
    }
    
    .container {
        padding: var(--spacing-lg) var(--spacing-sm);
    }
}

/* Mobile phones */
@media (max-width: 480px) {
    header h1 {
        font-size: 2rem;
    }
    
    header p {
        font-size: 1rem;
    }
    
    .font-demo {
        font-size: 1.1rem;
    }
    
    .section-description {
        font-size: 1rem;
        padding: var(--spacing-md);
    }
    
    .btn {
        width: 100%;
    }
}


/* ============================================
   ACCESSIBILITY
   ============================================ */

/* Focus visible for keyboard navigation */
a:focus-visible,
button:focus-visible,
.navigation__link:focus-visible {
    outline: 3px solid var(--color-primary);
    outline-offset: 2px;
}

/* Reduced motion for users who prefer it */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}


/* ============================================
   PRINT STYLES
   ============================================ */
@media print {
    body {
        background: white;
    }
    
    .navigation {
        display: none;
    }
    
    section {
        page-break-inside: avoid;
        box-shadow: none;
        border: 1px solid var(--color-border);
    }
    
    .color-card,
    .button-example {
        page-break-inside: avoid;
    }
}