/* Aspect Model Academic Website - Main Stylesheet */

/* CSS Variables for Theme */
:root {
    --primary-color: #2c3e50;
    --secondary-color: #34495e;
    --accent-color: #3498db;
    --accent-hover: #2980b9;
    --text-primary: #2c3e50;
    --text-secondary: #555;
    --text-light: #777;
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #e9ecef;
    --border-color: #dee2e6;
    --link-color: #3498db;
    --link-hover: #2980b9;
    --success-color: #27ae60;
    --error-color: #e74c3c;
    --warning-color: #f39c12;
    
    /* Typography */
    --font-serif: 'Georgia', 'Times New Roman', serif;
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Breakpoints */
    --breakpoint-sm: 576px;
    --breakpoint-md: 768px;
    --breakpoint-lg: 992px;
    --breakpoint-xl: 1200px;
}

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

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

body {
    font-family: var(--font-serif);
    color: var(--text-primary);
    background-color: var(--bg-primary);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-sans);
    font-weight: 600;
    line-height: 1.3;
    margin-bottom: var(--spacing-md);
    color: var(--primary-color);
}

h1 {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-lg);
}

h2 {
    font-size: 2rem;
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
}

h3 {
    font-size: 1.5rem;
    margin-top: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
}

h4 {
    font-size: 1.25rem;
    margin-top: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
}

p {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

a {
    color: var(--link-color);
    text-decoration: none;
    transition: color 0.3s ease;
}

a:hover, a:focus {
    color: var(--link-hover);
    text-decoration: underline;
}

a:focus {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

/* Lists */
ul, ol {
    margin-bottom: var(--spacing-md);
    padding-left: var(--spacing-lg);
}

li {
    margin-bottom: var(--spacing-xs);
    color: var(--text-secondary);
}

/* Site Header */
.site-header {
    background-color: var(--bg-primary);
    border-bottom: 2px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.main-nav {
    padding: var(--spacing-sm) 0;
}

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

.logo {
    font-family: var(--font-sans);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
}

.logo:hover {
    text-decoration: none;
    color: var(--accent-color);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-sm);
    padding: 0;
    margin: 0;
    align-items: center;
    flex-wrap: wrap;
}

.nav-menu li {
    margin: 0;
    white-space: nowrap;
}

.nav-menu a {
    color: var(--text-primary);
    font-family: var(--font-sans);
    font-weight: 500;
    font-size: 0.95rem;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: 4px;
    transition: background-color 0.3s ease, color 0.3s ease;
    display: inline-block;
    text-align: center;
    line-height: 1.4;
}

.nav-menu a:hover,
.nav-menu a.active {
    background-color: var(--bg-secondary);
    text-decoration: none;
    color: var(--accent-color);
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-xs);
}

.mobile-menu-toggle span {
    width: 25px;
    height: 3px;
    background-color: var(--primary-color);
    transition: all 0.3s ease;
}

/* Main Content */
.main-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-xl) var(--spacing-md);
    min-height: calc(100vh - 200px);
}

/* Site Footer */
.site-footer {
    background-color: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    padding: var(--spacing-lg) 0;
    margin-top: var(--spacing-xl);
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    text-align: center;
}

.footer-nav {
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    flex-wrap: wrap;
}

.footer-nav a {
    color: var(--text-secondary);
    font-family: var(--font-sans);
    font-size: 0.9rem;
}

.copyright {
    color: var(--text-light);
    font-size: 0.875rem;
    margin: 0;
}

/* Buttons */
button, .btn-primary, .btn-secondary, .btn-download {
    font-family: var(--font-sans);
    font-size: 1rem;
    padding: var(--spacing-xs) var(--spacing-md);
    border: 2px solid var(--accent-color);
    background-color: var(--accent-color);
    color: white;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
}

button:hover, .btn-primary:hover, .btn-secondary:hover, .btn-download:hover {
    background-color: var(--accent-hover);
    border-color: var(--accent-hover);
    text-decoration: none;
    color: white;
}

button:focus, .btn-primary:focus, .btn-secondary:focus, .btn-download:focus {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

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

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

/* Cards */
.concept-card, .resource-card {
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: var(--spacing-md);
    transition: box-shadow 0.3s ease, transform 0.3s ease;
}

.concept-card:hover, .resource-card:hover {
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    transform: translateY(-2px);
}

.resource-card {
    display: block;
    text-decoration: none;
    color: inherit;
}

.resource-card h3 {
    color: var(--accent-color);
    margin-bottom: var(--spacing-sm);
}

.resource-card:hover {
    text-decoration: none;
}

/* Grids */
.concepts-grid, .resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-md);
    margin: var(--spacing-lg) 0;
}

/* Sections */
.intro-section, .theory-overview, .resources-section {
    margin-bottom: var(--spacing-xl);
}

.subtitle {
    font-size: 1.25rem;
    color: var(--text-light);
    font-style: italic;
    margin-bottom: var(--spacing-lg);
}

/* Paper Content */
.paper-content {
    max-width: 900px;
}

.paper-header {
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-md);
    border-bottom: 2px solid var(--border-color);
}

.paper-controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.paper-toc {
    background-color: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 8px;
    margin-bottom: var(--spacing-xl);
}

.paper-toc h2 {
    margin-top: 0;
    font-size: 1.25rem;
}

.paper-toc ul {
    list-style: none;
    padding-left: 0;
}

.paper-toc li {
    margin-bottom: var(--spacing-xs);
}

.paper-toc a {
    color: var(--text-secondary);
}

.paper-section {
    margin-bottom: var(--spacing-xl);
}

.paper-section h2 {
    border-bottom: 1px solid var(--border-color);
    padding-bottom: var(--spacing-xs);
}

.references-list {
    list-style: decimal;
    padding-left: var(--spacing-lg);
}

.references-list li {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

/* Skip Link for Accessibility */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--primary-color);
    color: white;
    padding: 8px;
    text-decoration: none;
    z-index: 10000;
}

.skip-link:focus {
    top: 0;
}

/* Utility Classes */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

/* High Contrast Mode Support */
@media (prefers-contrast: high) {
    :root {
        --text-primary: #000000;
        --text-secondary: #000000;
        --bg-primary: #ffffff;
        --border-color: #000000;
    }
    
    a {
        text-decoration: underline;
    }
    
    button, .btn-primary {
        border-width: 3px;
    }
}

/* Reduced Motion Support */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    .flashcard-inner {
        transition: none;
    }
}

.text-center {
    text-align: center;
}

.last-updated {
    color: var(--text-light);
    font-size: 0.9rem;
    font-style: italic;
    margin-bottom: var(--spacing-lg);
}

/* Responsive Design */
@media (max-width: 768px) {
    html {
        font-size: 14px;
    }
    
    h1 {
        font-size: 2rem;
    }
    
    h2 {
        font-size: 1.75rem;
    }
    
    .main-content {
        padding: var(--spacing-md) var(--spacing-sm);
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background-color: var(--bg-primary);
        flex-direction: column;
        padding: var(--spacing-md);
        box-shadow: 0 4px 6px rgba(0,0,0,0.1);
        border-top: 1px solid var(--border-color);
    }
    
    .nav-menu.active {
        display: flex;
    }
    
    .concepts-grid, .resources-grid {
        grid-template-columns: 1fr;
    }
    
    .paper-controls {
        flex-direction: column;
        align-items: flex-start;
    }
}

@media (max-width: 576px) {
    h1 {
        font-size: 1.75rem;
    }
    
    .nav-container {
        padding: 0 var(--spacing-sm);
    }
}

/* Print Styles */
@media print {
    .site-header, .site-footer, .share-buttons-container, .paper-controls {
        display: none;
    }
    
    .main-content {
        max-width: 100%;
        padding: 0;
    }
    
    a {
        color: var(--text-primary);
    }
    
    a[href^="http"]:after {
        content: " (" attr(href) ")";
        font-size: 0.8em;
    }
}