/* NTU Student Resources Hub - Main Styling */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&display=swap');

/* CSS Variables - NTU Branding */
:root {
    /* Primary Colors - NTU Official */
    --ntu-blue: #003d7c;
    --ntu-red: #c7162b;
    --ntu-red-light: #e53e3e;
    --ntu-blue-light: #2a6496;
    
    /* Extended Palette */
    --ntu-blue-lighter: #e6f0ff;
    --ntu-red-lighter: #ffebed;
    --ntu-gray: #f8fafc;
    --ntu-gray-dark: #64748b;
    
    /* Neutral Colors */
    --white: #ffffff;
    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-400: #94a3b8;
    --gray-500: #64748b;
    --gray-600: #475569;
    --gray-700: #334155;
    --gray-800: #1e293b;
    --gray-900: #0f172a;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    
    /* Transitions */
    --transition: all 0.2s ease;
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 100px;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    line-height: 1.6;
    color: var(--gray-700);
    background-color: var(--white);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-family: 'Inter', sans-serif;
    font-weight: 700;
    line-height: 1.2;
    color: var(--gray-900);
}

/* Utility Classes */
.text-ntu-blue { color: var(--ntu-blue); }
.text-ntu-red { color: var(--ntu-red); }
.bg-ntu-blue { background-color: var(--ntu-blue); }
.bg-ntu-red { background-color: var(--ntu-red); }

/* Header */
.header {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--gray-200);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: var(--spacing-lg) 0;
}

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

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

.logo-title {
    font-size: 1.75rem;
    font-weight: 800;
    color: var(--ntu-blue);
    margin: 0;
}

.logo-subtitle {
    font-size: 0.95rem;
    color: var(--gray-500);
    margin: var(--spacing-xs) 0 0 0;
}

/* Hero Section */
.hero-section {
    background: linear-gradient(135deg, var(--ntu-blue) 0%, var(--ntu-blue-light) 100%);
    color: white;
    padding: var(--spacing-3xl) 0;
    position: relative;
    overflow: hidden;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><defs><pattern id="grid" width="10" height="10" patternUnits="userSpaceOnUse"><path d="M 10 0 L 0 0 0 10" fill="none" stroke="rgba(255,255,255,0.1)" stroke-width="0.5"/></pattern></defs><rect width="100" height="100" fill="url(%23grid)" /></svg>') center/cover;
}

.hero-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    position: relative;
    z-index: 1;
}

.hero-content {
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-lg);
    background: rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-xl);
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: var(--spacing-lg);
    backdrop-filter: blur(10px);
}

.hero-icon {
    width: 1rem;
    height: 1rem;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 900;
    line-height: 1.1;
    margin-bottom: var(--spacing-lg);
}

.gradient-text {
    background: linear-gradient(45deg, #fbbf24, #f59e0b, var(--ntu-red));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-description {
    font-size: 1.25rem;
    opacity: 0.9;
    margin-bottom: var(--spacing-2xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-stats {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--spacing-lg);
    flex-wrap: wrap;
}

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

.stat-number {
    font-size: 2.5rem;
    font-weight: 800;
    color: #fbbf24;
    line-height: 1;
}

.stat-label {
    font-size: 0.9rem;
    opacity: 0.8;
    margin-top: var(--spacing-xs);
}

.stat-divider {
    width: 1px;
    height: 40px;
    background: rgba(255, 255, 255, 0.3);
}

/* Main Content */
.main-content {
    min-height: 50vh;
}

.section {
    padding: var(--spacing-3xl) 0;
}

.section.alternate-bg {
    background-color: var(--gray-50);
}

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

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
}

.section-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-lg);
    background: linear-gradient(135deg, var(--ntu-blue) 0%, var(--ntu-blue-light) 100%);
    color: white;
    border-radius: var(--radius-xl);
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: var(--spacing-lg);
}

.badge-icon {
    width: 1rem;
    height: 1rem;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: var(--spacing-lg);
}

.section-description {
    font-size: 1.1rem;
    color: var(--gray-600);
    max-width: 600px;
    margin: 0 auto;
}

/* Tools Grid */
.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(450px, 1fr));
    gap: var(--spacing-2xl);
}

.tool-card {
    background: white;
    border-radius: var(--radius-2xl);
    padding: var(--spacing-2xl);
    box-shadow: var(--shadow-lg);
    transition: var(--transition);
    border: 2px solid transparent;
    position: relative;
    overflow: hidden;
}

.tool-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--gray-300);
}

.tool-card.featured::before {
    background: linear-gradient(90deg, var(--ntu-blue), var(--ntu-red));
}

.tool-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--ntu-blue-light);
}

.tool-header {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.tool-icon {
    width: 3rem;
    height: 3rem;
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    flex-shrink: 0;
}

.tool-icon i {
    width: 1.5rem;
    height: 1.5rem;
}

.tool-meta {
    flex: 1;
}

.tool-category {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--gray-500);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.tool-title {
    font-size: 1.5rem;
    font-weight: 700;
    margin: var(--spacing-xs) 0 0 0;
}

.tool-description {
    color: var(--gray-600);
    line-height: 1.6;
    margin-bottom: var(--spacing-lg);
}

.tool-features {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
}

.feature-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 0.9rem;
    color: var(--gray-600);
}

.feature-icon {
    width: 1rem;
    height: 1rem;
    color: var(--ntu-blue);
}

.tool-stats {
    display: flex;
    justify-content: space-between;
    padding: var(--spacing-lg);
    background: var(--gray-50);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-lg);
}

.stat {
    text-align: center;
}

.stat-value {
    display: block;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--gray-900);
    line-height: 1;
}

.stat-label {
    display: block;
    font-size: 0.8rem;
    color: var(--gray-500);
    margin-top: var(--spacing-xs);
}

.tool-button, .tool-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.tool-actions {
    gap: var(--spacing-md);
}

.tool-button {
    padding: var(--spacing-md) var(--spacing-xl);
    border-radius: var(--radius-lg);
    font-weight: 600;
    text-decoration: none;
    transition: var(--transition);
    border: 2px solid transparent;
    cursor: pointer;
    font-size: 1rem;
    justify-content: center;
    flex: 1;
}

.tool-button.primary {
    background: linear-gradient(135deg, var(--ntu-blue) 0%, var(--ntu-blue-light) 100%);
    color: white;
}

.tool-button.primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.tool-button.secondary {
    background: var(--gray-100);
    color: var(--gray-700);
    border-color: var(--gray-300);
}

.tool-button.secondary:hover {
    background: var(--gray-200);
    border-color: var(--ntu-blue);
    color: var(--ntu-blue);
}

.tool-button.download {
    background: linear-gradient(135deg, var(--ntu-red) 0%, var(--ntu-red-light) 100%);
    color: white;
    flex: 0 0 auto;
}

.tool-button.download:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.tool-button i {
    width: 1rem;
    height: 1rem;
}

/* Quick Access Grid */
.quick-access-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
}

.quick-action-card {
    background: white;
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
    border: 2px solid transparent;
}

.quick-action-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--ntu-blue-light);
}

.quick-action-icon {
    width: 3rem;
    height: 3rem;
    background: linear-gradient(135deg, var(--ntu-blue-lighter) 0%, var(--ntu-red-lighter) 100%);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-lg);
    color: var(--ntu-blue);
}

.quick-action-icon i {
    width: 1.5rem;
    height: 1.5rem;
}

.quick-action-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    color: var(--gray-900);
}

.quick-action-desc {
    font-size: 0.9rem;
    color: var(--gray-600);
    margin: 0;
}

/* Footer */
.footer {
    background: linear-gradient(135deg, var(--gray-900) 0%, var(--gray-800) 100%);
    color: white;
    padding: var(--spacing-3xl) 0 var(--spacing-xl) 0;
    margin-top: var(--spacing-3xl);
}

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

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-2xl);
    margin-bottom: var(--spacing-2xl);
}

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

.footer-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: white;
    margin: 0;
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--ntu-blue);
}

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

.footer-links a {
    color: var(--gray-300);
    text-decoration: none;
    transition: var(--transition);
    padding: var(--spacing-xs);
    border-radius: var(--radius-md);
}

.footer-links a:hover {
    color: var(--ntu-blue-light);
    background: rgba(42, 100, 150, 0.1);
    transform: translateX(4px);
}

.footer-info {
    color: var(--gray-300);
    margin: 0;
    line-height: 1.6;
}

.footer-bottom {
    border-top: 1px solid var(--gray-600);
    padding-top: var(--spacing-xl);
}

.footer-divider {
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--gray-600), transparent);
    margin-bottom: var(--spacing-lg);
}

.footer-bottom-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.footer-bottom-content p {
    color: var(--gray-400);
    margin: 0;
}

.back-to-top {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    color: var(--ntu-blue-light);
    text-decoration: none;
    font-weight: 500;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    background: rgba(42, 100, 150, 0.1);
    transition: var(--transition);
}

.back-to-top:hover {
    background: rgba(42, 100, 150, 0.2);
    transform: translateY(-2px);
}

.back-to-top i {
    width: 1rem;
    height: 1rem;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .hero-title {
        font-size: 3rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .tools-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .hero-title {
        font-size: 2.5rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
    
    .hero-stats {
        flex-direction: column;
        gap: var(--spacing-md);
    }
    
    .stat-divider {
        display: none;
    }
    
    .tool-header {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-md);
    }
    
    .tool-stats {
        flex-direction: column;
        gap: var(--spacing-md);
    }
    
    .tool-actions {
        flex-direction: column;
    }
    
    .footer-bottom-content {
        flex-direction: column;
        text-align: center;
    }
    
    .quick-access-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .section {
        padding: var(--spacing-2xl) 0;
    }
    
    .tool-card,
    .quick-action-card {
        padding: var(--spacing-lg);
    }
    
    .tools-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }
    
    .tools-grid .tool-card {
        min-width: unset;
    }
}