/* assets/css/style.css */
/* Modern, Premium Responsive Stylesheet for Online Course System */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Sarabun:wght@300;400;500;600;700&display=swap');

:root {
    /* Color Palette - Elegant Dark/Slate Theme with Violet Accent */
    --bg-primary: #0b0f19;
    --bg-secondary: #111827;
    --bg-card: rgba(17, 24, 39, 0.7);
    --border-color: rgba(255, 255, 255, 0.08);
    --border-hover: rgba(139, 92, 246, 0.4);
    
    --text-primary: #f3f4f6;
    --text-secondary: #9ca3af;
    --text-muted: #6b7280;
    
    --accent: #8b5cf6;
    --accent-hover: #7c3aed;
    --accent-glow: rgba(139, 92, 246, 0.15);
    
    --success: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
    
    --font-sans: 'Inter', 'Sarabun', sans-serif;
    --transition-smooth: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --border-radius: 12px;
    --shadow-premium: 0 10px 30px -10px rgba(0, 0, 0, 0.7);
    --shadow-glow: 0 0 20px rgba(139, 92, 246, 0.2);
}

/* Light Mode Override (if user preferences set - or we can keep it dark-first for a premium look) */
[data-theme="light"] {
    --bg-primary: #f8fafc;
    --bg-secondary: #ffffff;
    --bg-card: rgba(255, 255, 255, 0.85);
    --border-color: rgba(0, 0, 0, 0.06);
    --border-hover: rgba(139, 92, 246, 0.3);
    
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #94a3b8;
    
    --shadow-premium: 0 10px 30px -15px rgba(0, 0, 0, 0.1);
    --shadow-glow: 0 0 20px rgba(139, 92, 246, 0.08);
}

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

body {
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-family: var(--font-sans);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    overflow-x: hidden;
}

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

/* App Layout */
.app-header {
    background-color: rgba(11, 15, 25, 0.8);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1.25rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.4rem;
    font-weight: 700;
    background: linear-gradient(135deg, #fff 0%, #a78bfa 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    white-space: nowrap;
}

.logo-icon {
    color: var(--accent);
    filter: drop-shadow(0 0 8px var(--accent));
}

.nav-links {
    display: flex;
    gap: 1rem;
    align-items: center;
}

.nav-link {
    font-weight: 500;
    color: var(--text-secondary);
    transition: var(--transition-smooth);
    padding: 0.5rem 0.6rem;
    border-radius: 6px;
    white-space: nowrap;
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
}

.nav-link:hover, .nav-link.active {
    color: var(--text-primary);
    background-color: rgba(255, 255, 255, 0.05);
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.6rem 1.2rem;
    border-radius: var(--border-radius);
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition-smooth);
    border: none;
    font-size: 0.95rem;
}

.btn-primary {
    background-color: var(--accent);
    color: #ffffff;
    box-shadow: 0 4px 14px 0 rgba(139, 92, 246, 0.3);
}

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

.btn-secondary {
    background-color: rgba(255, 255, 255, 0.06);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: rgba(255, 255, 255, 0.1);
    border-color: var(--text-secondary);
}

.btn-danger {
    background-color: var(--danger);
    color: #ffffff;
}

.btn-danger:hover {
    background-color: #dc2626;
    transform: translateY(-1px);
}

.btn-sm {
    padding: 0.4rem 0.8rem;
    font-size: 0.85rem;
    border-radius: 8px;
}

/* Main Content Area */
.main-content {
    flex: 1;
    max-width: 1200px;
    width: 100%;
    margin: 0 auto;
    padding: 2.5rem 1.5rem;
}

/* Hero Section */
.hero {
    text-align: center;
    margin-bottom: 3.5rem;
    position: relative;
}

.hero::after {
    content: '';
    position: absolute;
    top: -50px;
    left: 50%;
    transform: translateX(-50%);
    width: 300px;
    height: 300px;
    background: radial-gradient(circle, rgba(139, 92, 246, 0.15) 0%, rgba(0,0,0,0) 70%);
    z-index: -1;
    pointer-events: none;
}

.hero-title {
    font-size: 3rem;
    font-weight: 800;
    letter-spacing: -0.025em;
    margin-bottom: 1rem;
    line-height: 1.2;
}

.hero-title span {
    background: linear-gradient(135deg, #a78bfa 0%, #8b5cf6 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-subtitle {
    font-size: 1.2rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto 1.5rem;
}

/* Course Grid */
.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 2rem;
}

.course-card {
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    transition: var(--transition-smooth);
    box-shadow: var(--shadow-premium);
}

.course-card:hover {
    transform: translateY(-5px);
    border-color: var(--border-hover);
    box-shadow: 0 20px 40px -15px rgba(0, 0, 0, 0.8), var(--shadow-glow);
}

.course-cover {
    width: 100%;
    height: 180px;
    object-fit: cover;
    border-bottom: 1px solid var(--border-color);
    background-color: var(--bg-secondary);
}

.course-info {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    flex-grow: 1;
}

.course-card-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
    line-height: 1.4;
}

.course-card-desc {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 1.5rem;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
    text-overflow: ellipsis;
    flex-grow: 1;
}

.course-card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-top: 1px solid var(--border-color);
    padding-top: 1rem;
    margin-top: auto;
}

.lesson-count {
    font-size: 0.85rem;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

/* Course Study Workspace (course.php) */
.course-workspace {
    display: grid;
    grid-template-columns: 320px 1fr;
    gap: 2rem;
    margin-top: 1rem;
}

.course-sidebar {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    height: calc(100vh - 120px);
    position: sticky;
    top: 90px;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.sidebar-header {
    padding: 1.25rem;
    border-bottom: 1px solid var(--border-color);
}

.sidebar-title {
    font-size: 1.1rem;
    font-weight: 700;
}

.sidebar-meta {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.lesson-list {
    list-style: none;
    overflow-y: auto;
    flex-grow: 1;
    padding: 0.75rem 0.5rem;
}

.lesson-item {
    margin-bottom: 0.25rem;
}

.lesson-link {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.85rem 1rem;
    border-radius: 8px;
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-secondary);
    transition: var(--transition-smooth);
    border-left: 3px solid transparent;
}

.lesson-link:hover {
    color: var(--text-primary);
    background-color: rgba(255, 255, 255, 0.03);
}

.lesson-link.active {
    color: var(--accent);
    background-color: rgba(139, 92, 246, 0.08);
    border-left-color: var(--accent);
}

.lesson-link-icon {
    font-size: 1rem;
}

/* Playback Area */
.play-area {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.video-container {
    position: relative;
    padding-bottom: 56.25%; /* 16:9 Aspect Ratio */
    height: 0;
    overflow: hidden;
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-premium);
    background-color: #000;
}

.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: 0;
}

.lesson-content {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow-premium);
}

.lesson-title {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.lesson-desc {
    color: var(--text-secondary);
    font-size: 1.05rem;
    white-space: pre-line;
}

/* Form Styles (Login & Admin) */
.form-card {
    max-width: 450px;
    width: 100%;
    margin: 4rem auto;
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 2.5rem;
    box-shadow: var(--shadow-premium);
}

.form-title {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    text-align: center;
}

.form-subtitle {
    color: var(--text-secondary);
    font-size: 0.95rem;
    text-align: center;
    margin-bottom: 2rem;
}

.form-group {
    margin-bottom: 1.25rem;
}

.form-label {
    display: block;
    font-weight: 500;
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.form-control {
    width: 100%;
    background-color: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 0.75rem 1rem;
    color: var(--text-primary);
    font-family: var(--font-sans);
    font-size: 1rem;
    transition: var(--transition-smooth);
}

.form-control:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.15);
    background-color: rgba(255, 255, 255, 0.05);
}

/* ปรับแต่งสไตล์ของเมนูดรอปดาวน์ (Select Options) สำหรับธีมมืด */
select.form-control option, select option {
    background-color: #111827;
    color: #f3f4f6;
    padding: 0.75rem;
}

textarea.form-control {
    resize: vertical;
    min-height: 120px;
}

/* Alert Notification */
.alert {
    padding: 1rem;
    border-radius: 8px;
    margin-bottom: 1.5rem;
    font-weight: 500;
    border: 1px solid transparent;
}

.alert-danger {
    background-color: rgba(239, 68, 68, 0.1);
    color: var(--danger);
    border-color: rgba(239, 68, 68, 0.2);
}

.alert-success {
    background-color: rgba(16, 185, 129, 0.1);
    color: var(--success);
    border-color: rgba(16, 185, 129, 0.2);
}

/* Admin Dashboard Table */
.dashboard-actions {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.dashboard-title {
    font-size: 1.75rem;
    font-weight: 700;
}

.data-table-container {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--shadow-premium);
    margin-bottom: 2rem;
}

.data-table {
    width: 100%;
    border-collapse: collapse;
    text-align: left;
}

.data-table th {
    background-color: rgba(255, 255, 255, 0.02);
    padding: 1rem 1.5rem;
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--text-secondary);
    border-bottom: 1px solid var(--border-color);
}

.data-table td {
    padding: 1.25rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-primary);
    font-size: 0.95rem;
}

.data-table tr:last-child td {
    border-bottom: none;
}

.data-table tr:hover td {
    background-color: rgba(255, 255, 255, 0.01);
}

.admin-thumb {
    width: 60px;
    height: 40px;
    border-radius: 4px;
    object-fit: cover;
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
}

.badge {
    display: inline-flex;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 600;
}

.badge-active {
    background-color: rgba(16, 185, 129, 0.1);
    color: var(--success);
}

.badge-inactive {
    background-color: rgba(239, 68, 68, 0.1);
    color: var(--danger);
}

.table-actions {
    display: flex;
    gap: 0.5rem;
}

/* Footer */
.app-footer {
    background-color: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    padding: 2rem 1.5rem;
    margin-top: auto;
    text-align: center;
}

.footer-text {
    color: var(--text-muted);
    font-size: 0.9rem;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 4rem 2rem;
    background: var(--bg-card);
    border: 1px dashed var(--border-color);
    border-radius: var(--border-radius);
    color: var(--text-secondary);
}

.empty-state-icon {
    font-size: 3rem;
    color: var(--text-muted);
    margin-bottom: 1rem;
}

/* Responsive Grid/Layout Breakpoints */
@media (max-width: 992px) {
    .course-workspace {
        grid-template-columns: 1fr;
    }
    
    .course-sidebar {
        height: auto;
        position: static;
    }
    
    .lesson-list {
        max-height: 250px;
    }
}

/* เมนูแฮมเบอร์เกอร์เริ่มต้นซ่อนไว้ */
.menu-toggle {
    display: none;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.4rem 0.8rem;
    border-radius: 8px;
    transition: var(--transition-smooth);
}

.menu-toggle:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--text-secondary);
}

/* Responsive Grid/Layout Breakpoints */
@media (max-width: 992px) {
    .course-workspace {
        grid-template-columns: 1fr;
    }
    
    .course-sidebar {
        height: auto;
        position: static;
    }
    
    .lesson-list {
        max-height: 250px;
    }
}

/* แท็บเล็ตและมือถือที่หน้าจอเล็กกว่า 1024px */
@media (max-width: 1024px) {
    .menu-toggle {
        display: block; /* แสดงปุ่มแฮมเบอร์เกอร์ */
    }

    .header-container {
        padding: 1rem 1.5rem;
        position: relative;
    }

    /* ซ่อนแถบเมนูในรูปแบบปกติ และเปิดแสดงเป็นเมนูสไลด์ลงมา */
    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background-color: rgba(11, 15, 25, 0.95);
        backdrop-filter: blur(20px);
        -webkit-backdrop-filter: blur(20px);
        border-bottom: 1px solid var(--border-color);
        padding: 1.5rem;
        flex-direction: column;
        align-items: stretch;
        gap: 0.75rem;
        z-index: 99;
        box-shadow: 0 15px 30px rgba(0,0,0,0.5);
    }

    .nav-links.open {
        display: flex; /* แสดงเมื่อเปิด */
        animation: slideDown 0.25s ease-out forwards;
    }

    .nav-link {
        width: 100%;
        padding: 0.8rem 1rem;
        border-radius: 8px;
    }

    .btn {
        width: 100%;
        padding: 0.8rem;
    }

    .main-content {
        padding: 1.5rem 1rem;
    }
    
    .hero-title {
        font-size: 2.25rem;
    }
}

/* หน้าจอมือถือขนาดเล็กมาก */
@media (max-width: 576px) {
    .form-card {
        padding: 1.5rem;
        margin: 2rem 0.5rem;
        border-radius: 12px;
    }
    
    .form-title {
        font-size: 1.5rem;
    }
    
    .form-subtitle {
        margin-bottom: 1.5rem;
    }

    .hero-title {
        font-size: 1.85rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }

    .lesson-content {
        padding: 1.25rem;
    }

    .lesson-title {
        font-size: 1.4rem;
    }

    .data-table th, .data-table td {
        padding: 0.75rem 0.5rem;
        font-size: 0.85rem;
    }
    
    .table-actions {
        flex-direction: column;
        gap: 0.35rem;
    }
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}