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

body {
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    color: #e2e8f0;
    background-color: #0f172a;
    font-size: 14px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Navigation */
.nav-bar {
    background: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid #334155;
    position: sticky;
    top: 0;
    z-index: 100;
    padding: 1rem 0;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: 1.2rem;
    font-weight: 700;
    color: #667eea;
}

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-link {
    color: #cbd5e1;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
}

.nav-link:hover {
    color: #667eea;
}

.nav-link i {
    font-size: 0.8rem;
}

/* Header */
.header {
    background: linear-gradient(135deg, #1e293b 0%, #334155 100%);
    color: white;
    padding: 2rem 0;
    text-align: center;
    border-bottom: 1px solid #334155;
}

.site-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.site-subtitle {
    font-size: 1rem;
    opacity: 0.9;
    font-weight: 300;
    color: #cbd5e1;
}

/* Main Content */
.main-content {
    padding: 2rem 0;
    background-color: #0f172a;
}

/* Session Information */
.session-info {
    margin-bottom: 2rem;
}

.session-info h2 {
    font-size: 1.4rem;
    margin-bottom: 1rem;
    color: #f1f5f9;
    text-align: center;
}

.timing-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.timing-card {
    background: #1e293b;
    padding: 1.2rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
    text-align: center;
    transition: transform 0.2s ease;
    border: 1px solid #334155;
}

.timing-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.4);
    border-color: #667eea;
}

.timing-card h3 {
    color: #667eea;
    margin-bottom: 0.5rem;
    font-size: 1rem;
}

.timing-card p {
    margin-bottom: 0.25rem;
    color: #cbd5e1;
    font-size: 0.9rem;
}

.location {
    font-weight: 600;
    color: #f1f5f9 !important;
}

/* General Resources */
.general-resources {
    margin-bottom: 2rem;
}

.general-resources h2 {
    font-size: 1.4rem;
    margin-bottom: 1rem;
    color: #f1f5f9;
    text-align: center;
}

.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 0.8rem;
}

.resource-card {
    background: #1e293b;
    padding: 0.8rem;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
    text-align: center;
    transition: all 0.2s ease;
    cursor: pointer;
    border: 1px solid #334155;
}

.resource-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.4);
    border-color: #667eea;
}

.resource-card i {
    font-size: 1.5rem;
    color: #667eea;
    margin-bottom: 0.4rem;
}

.resource-card h3 {
    font-size: 0.8rem;
    color: #f1f5f9;
    margin-bottom: 0.4rem;
}

.resource-card small {
    color: #94a3b8;
    font-size: 0.75rem;
}

/* Search and Filter Section */
.search-filter-section {
    margin-bottom: 1.5rem;
    background: #1e293b;
    padding: 1.2rem;
    border-radius: 12px;
    border: 1px solid #334155;
}

.search-container {
    display: flex;
    gap: 0.8rem;
    align-items: center;
    flex-wrap: wrap;
}

.search-box {
    flex: 1;
    min-width: 280px;
    position: relative;
    display: flex;
    align-items: center;
}

.search-box i {
    position: absolute;
    left: 10px;
    color: #94a3b8;
    z-index: 1;
    font-size: 0.9rem;
}

.search-box input {
    width: 100%;
    padding: 10px 35px 10px 35px;
    background: #0f172a;
    border: 1px solid #334155;
    border-radius: 8px;
    color: #f1f5f9;
    font-size: 0.9rem;
    transition: all 0.2s ease;
}

.search-box input:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.search-box input::placeholder {
    color: #94a3b8;
}

.clear-btn {
    position: absolute;
    right: 6px;
    background: none;
    border: none;
    color: #94a3b8;
    cursor: pointer;
    padding: 3px;
    border-radius: 4px;
    transition: all 0.2s ease;
    display: none;
    font-size: 0.8rem;
}

.clear-btn:hover {
    color: #f1f5f9;
    background: #334155;
}

.clear-btn.show {
    display: block;
}

.filter-options {
    display: flex;
    gap: 0.6rem;
    align-items: center;
}

.sort-select {
    padding: 8px 10px;
    background: #0f172a;
    border: 1px solid #334155;
    border-radius: 8px;
    color: #f1f5f9;
    font-size: 0.8rem;
    cursor: pointer;
    transition: all 0.2s ease;
}

.sort-select:focus {
    outline: none;
    border-color: #667eea;
}

.sort-select option {
    background: #0f172a;
    color: #f1f5f9;
}

.filter-toggle {
    padding: 8px 12px;
    background: #334155;
    border: 1px solid #475569;
    border-radius: 8px;
    color: #cbd5e1;
    font-size: 0.8rem;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.filter-toggle:hover {
    background: #475569;
    border-color: #667eea;
    color: #f1f5f9;
}

.search-results-info {
    margin-top: 0.8rem;
    padding: 0.6rem;
    background: #0f172a;
    border-radius: 6px;
    color: #94a3b8;
    font-size: 0.8rem;
    border: 1px solid #334155;
}

.search-results-info span {
    color: #667eea;
    font-weight: 600;
}

/* Semester Sections */
.semester-sections {
    margin-bottom: 2rem;
}

.semester-tabs {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    justify-content: center;
}

.tab-btn {
    padding: 0.6rem 1.2rem;
    background: #1e293b;
    border: 1px solid #334155;
    border-radius: 8px;
    color: #cbd5e1;
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 0.9rem;
    font-weight: 500;
}

.tab-btn.active {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

.tab-btn:hover:not(.active) {
    border-color: #667eea;
    color: #667eea;
    background: #1e293b;
}

.semester-content {
    margin-top: 1.5rem;
}

.semester-panel {
    display: none;
}

.semester-panel.active {
    display: block;
}

.semester-panel h2 {
    font-size: 1.4rem;
    margin-bottom: 1rem;
    color: #f1f5f9;
    text-align: center;
}

.sessions-grid {
    display: grid;
    gap: 0.8rem;
}

.session-card {
    background: #1e293b;
    padding: 1.2rem;
    border-radius: 12px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
    transition: transform 0.2s ease;
    border: 1px solid #334155;
}

.session-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.4);
    border-color: #667eea;
}

.session-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 0.8rem;
    flex-wrap: wrap;
    gap: 0.8rem;
}

.session-date {
    font-weight: 600;
    color: #667eea;
    font-size: 0.9rem;
}

.session-title {
    font-weight: 500;
    color: #f1f5f9;
    flex: 1;
    min-width: 180px;
    font-size: 0.9rem;
}

.session-files {
    display: flex;
    gap: 0.4rem;
    flex-wrap: wrap;
}

.file-link {
    display: inline-flex;
    align-items: center;
    gap: 0.2rem;
    padding: 0.4rem 0.6rem;
    background: #334155;
    border: 1px solid #475569;
    border-radius: 6px;
    text-decoration: none;
    color: #cbd5e1;
    font-size: 0.8rem;
    transition: all 0.2s ease;
}

.file-link:hover {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

.file-link i {
    font-size: 0.7rem;
}

/* Footer */
.footer {
    background: #1e293b;
    color: #cbd5e1;
    padding: 2rem 0 1rem;
    margin-top: 2rem;
    border-top: 1px solid #334155;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1.5rem;
    margin-bottom: 1.5rem;
}

.footer-section h3 {
    color: #667eea;
    font-size: 1.1rem;
    margin-bottom: 0.4rem;
}

.footer-section h4 {
    color: #f1f5f9;
    font-size: 0.9rem;
    margin-bottom: 0.8rem;
}

.footer-section p {
    margin-bottom: 0.4rem;
    color: #cbd5e1;
    font-size: 0.85rem;
}

.footer-section a {
    color: #cbd5e1;
    text-decoration: none;
    transition: color 0.2s ease;
    font-size: 0.85rem;
}

.footer-section a:hover {
    color: #667eea;
}

.social-links {
    display: flex;
    gap: 0.8rem;
    margin-top: 0.4rem;
}

.social-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 35px;
    height: 35px;
    background: #334155;
    border-radius: 50%;
    transition: all 0.2s ease;
    border: 1px solid #475569;
}

.social-link:hover {
    background: #667eea;
    border-color: #667eea;
    transform: translateY(-2px);
}

.social-link i {
    font-size: 1rem;
    color: #cbd5e1;
}

.social-link:hover i {
    color: white;
}

.footer-link {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    margin-bottom: 0.4rem;
    padding: 0.4rem 0;
}

.footer-link i {
    font-size: 0.8rem;
}

.footer-bottom {
    text-align: center;
    padding-top: 1.2rem;
    border-top: 1px solid #334155;
    color: #94a3b8;
    font-size: 0.8rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    body {
        font-size: 13px;
    }
    
    .site-title {
        font-size: 1.6rem;
    }
    
    .site-subtitle {
        font-size: 0.9rem;
    }
    
    .timing-grid {
        grid-template-columns: 1fr;
    }
    
    .resources-grid {
        grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    }
    
    .semester-tabs {
        flex-direction: column;
        align-items: center;
    }
    
    .session-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .session-files {
        width: 100%;
    }
    
    .nav-container {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav-links {
        gap: 1rem;
    }

    /* Search and Filter Responsive */
    .search-container {
        flex-direction: column;
        align-items: stretch;
    }
    
    .search-box {
        min-width: auto;
    }
    
    .filter-options {
        justify-content: space-between;
    }
    
    .sort-select {
        flex: 1;
        margin-right: 0.5rem;
    }
    
    .filter-toggle {
        white-space: nowrap;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .social-links {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    body {
        font-size: 12px;
    }
    
    .container {
        padding: 0 12px;
    }
    
    .site-title {
        font-size: 1.4rem;
    }
    
    .site-subtitle {
        font-size: 0.8rem;
    }
    
    .timing-card,
    .session-card {
        padding: 1rem;
    }
    
    .search-box input {
        font-size: 0.8rem;
        padding: 8px 30px 8px 30px;
    }
    
    .sort-select,
    .filter-toggle {
        font-size: 0.75rem;
        padding: 6px 8px;
    }
    
    .tab-btn {
        font-size: 0.8rem;
        padding: 0.5rem 1rem;
    }
    
    .session-title {
        font-size: 0.8rem;
    }
    
    .session-date {
        font-size: 0.8rem;
    }
    
    .file-link {
        font-size: 0.75rem;
        padding: 0.3rem 0.5rem;
    }
}

/* Loading Animation */
.loading {
    text-align: center;
    padding: 2rem;
    color: #667eea;
}

.loading::after {
    content: '';
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid #334155;
    border-top: 3px solid #667eea;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-left: 10px;
}

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

/* Empty State */
.empty-state {
    text-align: center;
    padding: 3rem;
    color: #94a3b8;
}

.empty-state i {
    font-size: 3rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}