/* --- CSS Variables (Corporate/Academic Theme) --- */
:root {
    /* TDMU Brand Colors */
    --primary-color: #002D72; /* Deep Blue */
    --primary-light: #00409A; 
    --accent-color: #F2A900; /* Gold */
    --accent-dark: #D49000;
    
    /* Semantic Colors */
    --student-color: #166534; /* Green */
    --teacher-color: #1E40AF; /* Blue */
    --cms-color: #5B21B6; /* Purple */
    
    /* Neutrals */
    --bg-color: #F3F4F6; /* Gray 100 */
    --surface-color: #FFFFFF;
    --text-primary: #111827; /* Gray 900 */
    --text-secondary: #4B5563; /* Gray 600 */
    --border-color: #E5E7EB; /* Gray 200 */
    
    /* UI Values */
    --border-radius: 6px;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
}

a {
    text-decoration: none;
    color: inherit;
}

.container {
    max-width: 1140px;
    margin: 0 auto;
    padding: 0 24px;
}

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

/* --- Header --- */
.header {
    background-color: var(--surface-color);
    border-bottom: 1px solid var(--border-color);
    padding: 16px 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--primary-color);
}

.logo-icon {
    font-size: 28px;
}

.logo-text {
    font-size: 20px;
    font-weight: 700;
    letter-spacing: -0.2px;
}

.lang-switcher {
    display: flex;
    align-items: center;
    background: var(--bg-color);
    padding: 4px;
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
}

.lang-btn {
    background: none;
    border: none;
    padding: 4px 12px;
    font-family: inherit;
    font-weight: 500;
    font-size: 13px;
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: calc(var(--border-radius) - 2px);
    transition: all 0.2s ease;
}

.lang-btn.active {
    background-color: var(--surface-color);
    color: var(--primary-color);
    box-shadow: var(--shadow-sm);
    font-weight: 600;
}

.divider {
    width: 1px;
    height: 16px;
    background-color: var(--border-color);
    margin: 0 4px;
}

/* --- Hero Section --- */
.hero {
    background-color: var(--primary-color);
    color: white;
    padding: 80px 0 120px 0;
    position: relative;
    border-bottom: 6px solid var(--accent-color);
}

.hero-title {
    font-size: 42px;
    font-weight: 700;
    margin-bottom: 16px;
    letter-spacing: -0.5px;
}

.hero-subtitle {
    font-size: 18px;
    font-weight: 400;
    color: rgba(255, 255, 255, 0.9);
    max-width: 700px;
    margin: 0 auto;
}

/* --- Navigation Cards --- */
.cards-section {
    margin-top: -60px; /* Pulls cards up over the hero */
    position: relative;
    z-index: 10;
}

.cards-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
    margin-bottom: 60px;
}

.solid-card {
    background-color: var(--surface-color);
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-md);
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.solid-card:hover {
    border-color: var(--accent-color);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

.card-icon-wrapper {
    padding: 24px;
    display: flex;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
}

.card-icon-wrapper span {
    font-size: 32px;
}

/* More professional colors for headers */
.student-theme { background-color: rgba(22, 101, 52, 0.05); color: var(--student-color); border-left: 4px solid var(--student-color); }
.teacher-theme { background-color: rgba(30, 64, 175, 0.05); color: var(--teacher-color); border-left: 4px solid var(--teacher-color); }
.cms-theme { background-color: rgba(91, 33, 182, 0.05); color: var(--cms-color); border-left: 4px solid var(--cms-color); }

.card-content {
    padding: 24px;
    display: flex;
    flex-direction: column;
    flex-grow: 1;
}

.card-title {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.card-desc {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 32px;
    flex-grow: 1;
}

.card-action {
    display: flex;
    align-items: center;
    gap: 6px;
    font-weight: 600;
    color: var(--primary-color);
    font-size: 14px;
}

.solid-card:hover .card-action {
    color: var(--accent-dark);
}

/* --- Download Section --- */
.download-section {
    margin-bottom: 80px;
}

.section-title {
    font-size: 28px;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 32px;
    text-align: center;
}

.download-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
}

.download-banner {
    display: flex;
    flex-direction: column;
    background-color: var(--surface-color);
}

.student-app-card {
    border-top: 4px solid var(--student-color);
}

.teacher-app-card {
    border-top: 4px solid var(--teacher-color);
}

.app-icon-wrapper {
    width: 56px;
    height: 56px;
    border-radius: var(--border-radius);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
}

.app-icon-wrapper span {
    font-size: 32px;
}

.download-content {
    padding: 40px;
    display: flex;
    flex-direction: column;
    flex-grow: 1;
}

.download-title {
    font-size: 22px;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.download-desc {
    color: var(--text-secondary);
    margin-bottom: 32px;
    font-size: 15px;
    flex-grow: 1;
}

.download-buttons {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

.store-btn {
    display: flex;
    align-items: center;
    gap: 12px;
    background-color: var(--text-primary);
    color: var(--surface-color);
    border: 1px solid transparent;
    padding: 8px 20px;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: background-color 0.2s ease;
}

.store-btn:hover {
    background-color: #000000;
}

.store-btn span.material-symbols-outlined {
    font-size: 24px;
}

.store-btn-text {
    text-align: left;
    display: flex;
    flex-direction: column;
}

.store-btn-text .small-text {
    font-size: 11px;
    opacity: 0.9;
}

.store-btn-text .large-text {
    font-size: 15px;
    font-weight: 600;
}

/* --- Footer --- */
.footer {
    padding-bottom: 40px;
}

.footer-divider {
    height: 1px;
    background-color: var(--border-color);
    margin-bottom: 24px;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--text-secondary);
    font-size: 13px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 600;
}

/* --- Responsive --- */
@media (max-width: 900px) {
    .cards-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .download-banner {
        flex-direction: column;
        align-items: stretch;
    }
    
    .download-illustration {
        border-left: none;
        border-top: 1px solid var(--border-color);
        padding: 32px;
    }
    
    .footer-content {
        flex-direction: column;
        gap: 16px;
        text-align: center;
    }
}

@media (max-width: 600px) {
    .cards-grid {
        grid-template-columns: 1fr;
    }
    
    .hero-title {
        font-size: 32px;
    }
}