/* Base Styles & Theme Colors */
:root {
    --bg-color: #0f172a;
    --sidebar-bg: #1e293b;
    --card-bg: #1e293b;
    --accent-color: #0ea5e9;
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --border-color: #334155;
    --success-color: #10b981;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-main);
    display: flex;
    height: 100vh;
    overflow: hidden;
}

/* Sidebar Layout */
.sidebar {
    width: 260px;
    background-color: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    padding: 20px;
    justify-content: space-between;
    overflow-y: auto;
    flex-shrink: 0;
}

.logo-section {
    padding: 10px 0 30px 0;
    font-size: 1.4rem;
    font-weight: bold;
    color: var(--accent-color);
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 20px;
    display: flex;
    align-items: center;
}

.logo-section img {
    height: 36px !important;
    width: 36px !important;
    max-width: 36px !important;
    object-fit: contain;
    display: block;
}

.nav-links {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 10px;
    flex-grow: 1; 
}

.nav-item {
    padding: 12px 15px;
    border-radius: 8px;
    cursor: pointer;
    color: var(--text-muted);
    font-weight: 500;
    transition: all 0.3s ease;
}

.nav-item:hover, .nav-item.active {
    background-color: var(--border-color);
    color: var(--text-main);
}

.nav-item.active {
    border-left: 4px solid var(--accent-color);
    background-color: rgba(14, 165, 233, 0.1);
}

.admin-tab {
    color: #f59e0b;
}

/* Main Content Container */
.main-container {
    flex: 1;
    padding: 40px;
    overflow-y: auto;
}

.page-section {
    display: none;
}

.page-section.active-section {
    display: block;
}

h2 {
    font-size: 1.8rem;
    margin-bottom: 20px;
}

/* Dashboard UI Components */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.stat-card {
    background-color: var(--card-bg);
    padding: 20px;
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.stat-card h3 {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 10px;
}

.stat-card .value {
    font-size: 2rem;
    font-weight: bold;
    color: var(--text-main);
}

/* Progress Bar */
.progress-container {
    width: 100%;
    background-color: var(--border-color);
    border-radius: 10px;
    height: 10px;
    margin-top: 15px;
}

.progress-bar {
    background-color: var(--success-color);
    height: 100%;
    border-radius: 10px;
    transition: width 0.3s ease;
}

/* Learning Resources Grid */
.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
}

.course-card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 25px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.course-card h3 {
    margin-bottom: 10px;
    color: var(--text-main);
}

.course-card p {
    color: var(--text-muted);
    font-size: 0.95rem;
    line-height: 1.5;
    margin-bottom: 20px;
}

.btn {
    background-color: var(--accent-color);
    color: #fff;
    border: none;
    padding: 12px 20px;
    border-radius: 8px;
    cursor: pointer;
    font-weight: bold;
    text-align: center;
    text-decoration: none;
    transition: opacity 0.2s;
}

.btn:hover {
    opacity: 0.9;
}

/* Video Reader Aspect Ratio Container */
.video-container {
    position: relative;
    padding-bottom: 56.25%; /* 16:9 Aspect Ratio */
    height: 0;
    overflow: hidden;
    max-width: 100%;
    border-radius: 12px;
    margin: 20px 0;
    border: 1px solid var(--border-color);
}

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

.reader-view {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 30px;
    margin-top: 20px;
}

.reader-content {
    line-height: 1.7;
    color: #e2e8f0;
}

/* Telegram Page */
.telegram-card {
    background-color: #1d2a3a;
    border: 1px solid #2b3d54;
    padding: 40px;
    border-radius: 12px;
    text-align: center;
    max-width: 500px;
    margin: 0 auto;
}

.telegram-btn {
    background-color: #229ED9;
    margin-top: 20px;
    display: inline-block;
}

/* Profile Form Layout & Admin Cards */
.profile-form, .admin-card {
    background-color: var(--card-bg);
    padding: 30px;
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    color: var(--text-muted);
}

.form-group input, .form-input {
    width: 100%;
    padding: 12px;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: white;
}

.logout-item {
    padding: 12px 15px;
    border-radius: 8px;
    cursor: pointer;
    color: #94a3b8;
    font-weight: 600;
    margin-top: auto;
    transition: all 0.2s ease-in-out;
}

.logout-item:hover {
    background-color: rgba(239, 68, 68, 0.1);
    color: #ef4444;
}

.badge {
    font-size: 0.75rem;
    padding: 4px 8px;
    border-radius: 20px;
    margin-left: 10px;
    font-weight: bold;
    display: inline-block;
}

.watch-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.watch-list-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    padding: 9px 12px;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.88rem;
    transition: border-color 0.2s ease;
}

.watch-list-item:hover {
    border-color: var(--accent-color);
}

.watch-list-item span:first-child {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.completed-badge {
    background-color: rgba(16, 185, 129, 0.15);
    color: var(--success-color);
    border: 1px solid rgba(16, 185, 129, 0.3);
}

/* Checkbox Styling */
.completion-checkbox-container {
    display: flex;
    align-items: center;
    position: relative;
    padding-left: 30px;
    cursor: pointer;
    font-size: 0.95rem;
    color: var(--text-main);
    user-select: none;
    font-weight: 500;
}

.completion-checkbox-container input {
    position: absolute;
    opacity: 0;
    cursor: pointer;
    height: 0;
    width: 0;
}

.custom-checkmark {
    position: absolute;
    top: -2px;
    left: 0;
    height: 20px;
    width: 20px;
    background-color: var(--bg-color);
    border: 2px solid var(--border-color);
    border-radius: 6px;
    transition: all 0.2s ease;
}

.completion-checkbox-container:hover input ~ .custom-checkmark {
    border-color: var(--accent-color);
}

.completion-checkbox-container input:checked ~ .custom-checkmark {
    background-color: var(--success-color);
    border-color: var(--success-color);
}

.custom-checkmark:after {
    content: "";
    position: absolute;
    display: none;
}

.completion-checkbox-container input:checked ~ .custom-checkmark:after {
    display: block;
}

.completion-checkbox-container .custom-checkmark:after {
    left: 6px;
    top: 2px;
    width: 5px;
    height: 10px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

/* Admin Table */
.admin-table {
    width: 100%;
    border-collapse: collapse;
    color: var(--text-main);
}

.admin-table th, .admin-table td {
    padding: 12px 15px;
    border: 1px solid var(--border-color);
    text-align: left;
}

.admin-table th {
    background-color: var(--bg-color);
    color: var(--text-muted);
}

/* Mobile Nav Toggle (hidden on desktop) */
.mobile-topbar {
    display: none;
}

.sidebar-backdrop {
    display: none;
}

/* Mobile Layout & Scroll Fixes */
@media (max-width: 768px) {
    body {
        flex-direction: column;
        height: 100%;
        min-height: 100dvh;
        overflow-y: auto !important;
        -webkit-overflow-scrolling: touch;
    }

    .mobile-topbar {
        display: flex;
        align-items: center;
        justify-content: space-between;
        background-color: var(--sidebar-bg);
        border-bottom: 1px solid var(--border-color);
        padding: 14px 20px;
        flex-shrink: 0;
    }

    .mobile-topbar .logo-section {
        border-bottom: none;
        margin-bottom: 0;
        padding: 0;
        font-size: 1.2rem;
    }

    .mobile-topbar .logo-section img {
        height: 28px !important;
        width: 28px !important;
        max-width: 28px !important;
    }

    .menu-toggle-btn {
        background: none;
        border: 1px solid var(--border-color);
        color: var(--text-main);
        font-size: 1.3rem;
        line-height: 1;
        padding: 6px 12px;
        border-radius: 8px;
        cursor: pointer;
    }

    /* FIX: Scrollable Mobile Sidebar Layout */
    .sidebar {
        position: fixed;
        top: 0;
        left: 0;
        width: 260px;
        height: 100vh;
        height: 100dvh;
        max-height: 100dvh;
        z-index: 1001;
        transform: translateX(-100%);
        transition: transform 0.25s ease;
        box-shadow: 4px 0 20px rgba(0, 0, 0, 0.4);
        
        display: flex;
        flex-direction: column;
        justify-content: flex-start;
        overflow-y: auto !important;
        -webkit-overflow-scrolling: touch;
        padding-bottom: 60px;
    }

    .sidebar.open {
        transform: translateX(0);
    }

    .nav-links {
        flex-grow: 0;
        margin-bottom: 20px;
    }

    .logout-item {
        margin-top: auto;
        padding: 14px 15px;
        margin-bottom: 20px;
        flex-shrink: 0;
    }

    .sidebar-backdrop {
        display: none;
        position: fixed;
        inset: 0;
        background: rgba(0, 0, 0, 0.5);
        z-index: 1000;
    }

    .sidebar-backdrop.open {
        display: block;
    }

    /* FIX: Smooth Full-Height Vertical Touch Scrolling for Main Content */
    .main-container {
        flex: 1;
        width: 100%;
        padding: 20px 15px 80px 15px;
        overflow-y: auto !important;
        -webkit-overflow-scrolling: touch;
        height: auto;
    }

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

    .resources-grid {
        grid-template-columns: 1fr;
        gap: 16px;
        padding-bottom: 20px;
    }
}