/* ====================================================================
   HSC Software Engineering Hub - Shared Styles
   Multi-Page Architecture - Common CSS
   ==================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&display=swap');

/* ==================== ROOT VARIABLES ==================== */
:root {
    /* Colors */
    --color-primary: #3b82f6;
    --color-primary-hover: #2563eb;
    --color-secondary: #8b5cf6;
    --color-success: #10b981;
    --color-warning: #f59e0b;
    --color-danger: #ef4444;
    --color-info: #06b6d4;

    /* Grays */
    --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;

    /* Year Colors */
    --year11-color: #10b981;
    --year11-bg: #d1fae5;
    --year12-color: #8b5cf6;
    --year12-bg: #ede9fe;

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Border */
    --border-radius: 0.5rem;
    --border-radius-lg: 0.75rem;
    --border-width: 1px;

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

    /* 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);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    line-height: 1.7;
    letter-spacing: 0.025em;
    color: var(--gray-800);
    background-color: var(--gray-50);
}

/* ==================== TYPOGRAPHY ==================== */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.3;
    color: var(--gray-900);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.125rem; }
h6 { font-size: 1rem; }

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

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

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

/* ==================== HEADER/NAVIGATION ==================== */
.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--gray-200);
    box-shadow: var(--shadow-sm);
}

.header-container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 4rem;
}

.site-logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--gray-900);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.site-logo:hover {
    color: var(--gray-900);
}

.breadcrumb {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.875rem;
    color: var(--gray-500);
}

.breadcrumb-separator {
    color: var(--gray-300);
}

.breadcrumb-current {
    color: var(--gray-700);
    font-weight: 600;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.btn-icon {
    padding: 0.5rem;
    border-radius: var(--border-radius);
    background: transparent;
    border: none;
    cursor: pointer;
    transition: background-color var(--transition-base);
    color: var(--gray-600);
}

.btn-icon:hover {
    background-color: var(--gray-100);
    color: var(--gray-900);
}

.progress-badge {
    padding: 0.25rem 0.75rem;
    background-color: var(--color-primary);
    color: white;
    border-radius: 9999px;
    font-size: 0.75rem;
    font-weight: 600;
}

/* ==================== MAIN NAVIGATION ==================== */
.main-nav {
    background: white;
    border-bottom: 1px solid var(--gray-200);
    margin-bottom: var(--spacing-xl);
}

.nav-container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.nav-links {
    display: flex;
    gap: var(--spacing-md);
    list-style: none;
    overflow-x: auto;
    padding: 0.5rem 0;
}

.nav-link {
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    font-size: 0.875rem;
    font-weight: 500;
    white-space: nowrap;
    transition: all var(--transition-base);
}

.nav-link:hover {
    background-color: var(--gray-100);
}

.nav-link.active {
    background-color: var(--color-primary);
    color: white;
}

/* ==================== CONTENT LAYOUT ==================== */
.page-container {
    max-width: 1280px;
    margin: 0 auto;
    padding: var(--spacing-xl) var(--spacing-lg);
}

.content-section {
    margin-bottom: var(--spacing-2xl);
}

.section-header {
    margin-bottom: var(--spacing-lg);
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: 0.5rem;
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--gray-600);
}

/* ==================== CARDS ==================== */
.card {
    background: white;
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--gray-200);
    transition: all var(--transition-base);
}

.card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--spacing-lg);
}

.card-header {
    margin-bottom: var(--spacing-md);
}

.card-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--gray-900);
}

.card-body {
    color: var(--gray-700);
}

/* ==================== BUTTONS ==================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.625rem 1.25rem;
    font-size: 0.875rem;
    font-weight: 600;
    border-radius: var(--border-radius);
    border: none;
    cursor: pointer;
    transition: all var(--transition-base);
    text-decoration: none;
}

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

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

.btn-secondary {
    background-color: var(--gray-200);
    color: var(--gray-700);
}

.btn-secondary:hover {
    background-color: var(--gray-300);
    color: var(--gray-900);
}

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

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

.btn-lg {
    padding: 0.875rem 1.75rem;
    font-size: 1rem;
}

/* ==================== BADGES ==================== */
.badge {
    display: inline-flex;
    align-items: center;
    padding: 0.25rem 0.75rem;
    font-size: 0.75rem;
    font-weight: 600;
    border-radius: 9999px;
}

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

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

.badge-warning {
    background-color: var(--color-warning);
    color: white;
}

.badge-year11 {
    background-color: var(--year11-bg);
    color: var(--year11-color);
}

.badge-year12 {
    background-color: var(--year12-bg);
    color: var(--year12-color);
}

/* ==================== PROGRESS BARS ==================== */
.progress-bar-container {
    width: 100%;
    height: 0.5rem;
    background-color: var(--gray-200);
    border-radius: 9999px;
    overflow: hidden;
}

.progress-bar-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
    transition: width var(--transition-slow);
}

/* ==================== FOOTER ==================== */
.site-footer {
    background: var(--gray-800);
    color: var(--gray-300);
    padding: var(--spacing-xl) 0;
    margin-top: var(--spacing-2xl);
}

.footer-container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

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

.footer-link {
    color: var(--gray-300);
    font-size: 0.875rem;
}

.footer-link:hover {
    color: white;
}

.footer-copyright {
    font-size: 0.875rem;
    color: var(--gray-400);
    text-align: center;
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--gray-700);
}

/* ==================== UTILITY CLASSES ==================== */
.text-center { text-align: center; }
.text-right { text-align: right; }
.font-bold { font-weight: 700; }
.font-semibold { font-weight: 600; }
.text-sm { font-size: 0.875rem; }
.text-lg { font-size: 1.125rem; }
.text-xl { font-size: 1.25rem; }

.mb-xs { margin-bottom: var(--spacing-xs); }
.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }

.mt-xs { margin-top: var(--spacing-xs); }
.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }

/* ==================== RESPONSIVE ==================== */
@media (max-width: 768px) {
    h1 { font-size: 2rem; }
    h2 { font-size: 1.75rem; }
    h3 { font-size: 1.25rem; }

    .page-container {
        padding: var(--spacing-lg) var(--spacing-md);
    }

    .breadcrumb {
        display: none;
    }

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