/* ========== Main Layout ========== */
.main-layout {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ========== Top Bar ========== */
.top-bar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 var(--space-6);
    height: var(--topbar-height);
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(12px);
    background: rgba(255, 255, 255, 0.92);
}

.brand {
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--color-text);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: var(--space-2);
    letter-spacing: -0.02em;
}

.brand:hover {
    color: var(--color-primary);
}

.top-bar-right {
    display: flex;
    align-items: center;
    gap: var(--space-4);
}

/* ========== Login Display ========== */
.login-display {
    display: flex;
    align-items: center;
    gap: var(--space-3);
}

.user-avatar {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    border: 2px solid var(--color-gray-200);
}

.user-name {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text);
}

.logout-btn {
    color: var(--color-text-secondary);
    text-decoration: none;
    font-size: 0.8125rem;
    padding: 0.25rem 0.75rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    transition: all var(--transition);
}

.logout-btn:hover {
    color: var(--color-danger);
    border-color: var(--color-danger);
    background: var(--color-danger-light);
}

.login-link {
    color: var(--color-primary);
    text-decoration: none;
    font-weight: 500;
}

.admin-link {
    font-size: 0.8125rem;
    padding: 0.25rem 0.75rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    color: var(--color-text-secondary);
    text-decoration: none;
    transition: all var(--transition);
}

.admin-link:hover {
    background: var(--color-primary-lightest);
    border-color: var(--color-primary);
    color: var(--color-primary);
}

/* ========== Main Content ========== */
.main-content {
    flex: 1;
    padding: var(--space-8) var(--space-6);
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
}

/* ========== Course Catalog ========== */
.catalog-container {
    padding: 0;
}

.catalog-header {
    margin-bottom: var(--space-8);
}

.catalog-title {
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: -0.03em;
    margin-bottom: var(--space-2);
}

.catalog-subtitle {
    color: var(--color-text-secondary);
    font-size: 1.0625rem;
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: var(--space-5);
}

.course-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    overflow: hidden;
    cursor: pointer;
    transition: all var(--transition);
    box-shadow: var(--shadow-xs);
}

.course-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-gray-300);
}

.course-card-cover {
    height: 180px;
    background-size: cover;
    background-position: center;
    background-color: var(--color-gray-100);
    position: relative;
}

.course-card-cover-default {
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: #fff;
    font-size: 3.5rem;
    font-weight: 700;
    letter-spacing: -0.03em;
}

.course-card-body {
    padding: var(--space-5);
}

.course-card-title {
    font-size: 1.125rem;
    font-weight: 600;
    margin: 0 0 var(--space-2) 0;
    letter-spacing: -0.01em;
}

.course-card-desc {
    color: var(--color-text-secondary);
    font-size: 0.875rem;
    line-height: 1.5;
    margin: 0 0 var(--space-4) 0;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.course-card-meta {
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.source-badge {
    font-size: 0.6875rem;
    font-weight: 600;
    padding: 0.125rem 0.5rem;
    border-radius: 9999px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.source-badge.local {
    background: var(--color-primary-lightest);
    color: var(--color-primary);
}

.source-badge.github {
    background: var(--color-success-light);
    color: var(--color-success);
}

.empty-state {
    text-align: center;
    padding: var(--space-12) var(--space-6);
    color: var(--color-text-secondary);
}

.empty-state h3 {
    font-size: 1.25rem;
    color: var(--color-text);
    margin-bottom: var(--space-2);
}

/* ========== Course Reader Layout ========== */
.course-reader-layout {
    display: flex;
    min-height: calc(100vh - var(--topbar-height));
    margin: calc(-1 * var(--space-8)) calc(-1 * var(--space-6));
}

.course-sidebar {
    width: var(--sidebar-width);
    min-width: var(--sidebar-width);
    background: var(--color-surface);
    border-right: 1px solid var(--color-border);
    overflow-y: auto;
    height: calc(100vh - var(--topbar-height));
    position: sticky;
    top: var(--topbar-height);
    transition: margin-left 0.3s ease;
    scrollbar-width: thin;
    scrollbar-color: var(--color-gray-300) transparent;
}

.course-sidebar::-webkit-scrollbar {
    width: 6px;
}

.course-sidebar::-webkit-scrollbar-track {
    background: transparent;
}

.course-sidebar::-webkit-scrollbar-thumb {
    background: var(--color-gray-300);
    border-radius: 3px;
}

.course-sidebar.collapsed {
    margin-left: calc(-1 * var(--sidebar-width));
}

.course-content-area {
    flex: 1;
    padding: var(--space-8) var(--space-10);
    max-width: 820px;
    min-width: 0;
}

/* ========== Sidebar Navigation ========== */
.sidebar-nav {
    padding: var(--space-4) 0;
}

.sidebar-header {
    padding: var(--space-3) var(--space-5) var(--space-4);
    border-bottom: 1px solid var(--color-border);
}

.sidebar-header h3 {
    font-size: 0.9375rem;
    font-weight: 600;
    color: var(--color-text);
    letter-spacing: -0.01em;
}

.chapter-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.chapter-item {
    margin-top: var(--space-1);
}

.chapter-toggle {
    display: flex;
    align-items: center;
    width: 100%;
    padding: 0.5rem var(--space-5);
    background: none;
    border: none;
    cursor: pointer;
    font-size: 0.8125rem;
    font-weight: 600;
    color: var(--color-text);
    text-align: left;
    gap: var(--space-2);
    text-transform: uppercase;
    letter-spacing: 0.04em;
    transition: background var(--transition);
}

.chapter-toggle:hover {
    background: var(--color-hover);
}

.toggle-icon {
    font-size: 0.625rem;
    width: 14px;
    color: var(--color-text-muted);
    transition: transform var(--transition);
}

.lesson-list {
    list-style: none;
    padding: 0 0 var(--space-2) 0;
    margin: 0;
}

.lesson-item {
    border-left: 2px solid transparent;
    margin-left: var(--space-5);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.lesson-item.active {
    border-left-color: var(--color-primary);
    background: var(--color-primary-lightest);
}

.lesson-link {
    display: block;
    padding: 0.375rem var(--space-4);
    color: var(--color-text-secondary);
    text-decoration: none;
    font-size: 0.875rem;
    transition: all var(--transition);
    line-height: 1.4;
}

.lesson-link:hover {
    color: var(--color-text);
    background: var(--color-hover);
}

.lesson-item.active .lesson-link {
    color: var(--color-primary);
    font-weight: 500;
}

/* ========== Lesson Navigation ========== */
.lesson-nav {
    display: flex;
    justify-content: space-between;
    margin-top: var(--space-10);
    padding-top: var(--space-6);
    border-top: 1px solid var(--color-border);
    gap: var(--space-4);
}

.nav-prev, .nav-next {
    display: flex;
    flex-direction: column;
    color: var(--color-text);
    text-decoration: none;
    padding: var(--space-4);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    transition: all var(--transition);
    flex: 1;
    max-width: 50%;
}

.nav-prev:hover, .nav-next:hover {
    border-color: var(--color-primary);
    background: var(--color-primary-lightest);
    color: var(--color-primary);
}

.nav-next {
    text-align: right;
    margin-left: auto;
}

.access-denied-msg, .not-found-msg {
    text-align: center;
    padding: var(--space-12) var(--space-6);
}

.access-denied-msg h2, .not-found-msg h2 {
    margin-bottom: var(--space-3);
}

/* ========== Sidebar Toggle ========== */
.sidebar-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--color-text);
    font-size: 1.25rem;
    cursor: pointer;
    padding: var(--space-2);
    border-radius: var(--radius-sm);
    transition: background var(--transition);
}

.sidebar-toggle:hover {
    background: var(--color-hover);
}

/* ========== Admin Layout ========== */
.admin-layout {
    display: flex;
    min-height: calc(100vh - var(--topbar-height));
}

.admin-sidebar {
    width: 240px;
    min-width: 240px;
    background: var(--color-surface);
    border-right: 1px solid var(--color-border);
    padding: var(--space-4) 0;
}

.admin-sidebar-label {
    font-size: 0.6875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--color-text-muted);
    padding: var(--space-4) var(--space-5) var(--space-2);
}

.admin-sidebar a {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: 0.5rem var(--space-5);
    color: var(--color-text-secondary);
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 500;
    border-radius: 0;
    transition: all var(--transition);
    border-left: 2px solid transparent;
}

.admin-sidebar a:hover {
    background: var(--color-hover);
    color: var(--color-text);
}

.admin-sidebar a.active {
    background: var(--color-primary-lightest);
    color: var(--color-primary);
    border-left-color: var(--color-primary);
}

.admin-sidebar-divider {
    height: 1px;
    background: var(--color-border);
    margin: var(--space-3) var(--space-5);
}

.admin-content {
    flex: 1;
    padding: var(--space-6) var(--space-8);
    max-width: 960px;
}

/* ========== Form Card ========== */
.form-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-6);
    margin: var(--space-5) 0;
    box-shadow: var(--shadow-sm);
}

.form-card h3 {
    margin-bottom: var(--space-5);
    padding-bottom: var(--space-4);
    border-bottom: 1px solid var(--color-border);
}

/* ========== Responsive ========== */
@media (max-width: 768px) {
    .top-bar {
        padding: 0 var(--space-4);
    }

    .main-content {
        padding: var(--space-5) var(--space-4);
    }

    .sidebar-toggle {
        display: flex;
    }

    .course-sidebar {
        position: fixed;
        top: var(--topbar-height);
        left: 0;
        z-index: 90;
        box-shadow: var(--shadow-xl);
    }

    .course-sidebar.collapsed {
        margin-left: calc(-1 * var(--sidebar-width));
    }

    .course-content-area {
        padding: var(--space-5);
    }

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

    .course-reader-layout {
        margin: calc(-1 * var(--space-5)) calc(-1 * var(--space-4));
    }

    .admin-layout {
        flex-direction: column;
    }

    .admin-sidebar {
        width: 100%;
        min-width: 100%;
        display: flex;
        overflow-x: auto;
        border-right: none;
        border-bottom: 1px solid var(--color-border);
        padding: var(--space-2);
        gap: var(--space-1);
    }

    .admin-sidebar a {
        white-space: nowrap;
        padding: var(--space-2) var(--space-3);
        border-radius: var(--radius-sm);
        border-left: none;
    }

    .admin-sidebar-label,
    .admin-sidebar-divider {
        display: none;
    }

    .admin-content {
        padding: var(--space-5) var(--space-4);
    }
}

/* ========== Theme Toggle Button ========== */
.theme-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    padding: 0;
    background: transparent;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    color: var(--color-text-secondary);
    cursor: pointer;
    transition: all var(--transition);
}

.theme-toggle:hover {
    color: var(--color-text);
    border-color: var(--color-gray-300);
    background: var(--color-hover);
}

/* ========== Dark Mode Component Overrides ========== */
html.dark .top-bar {
    background: rgba(26, 27, 30, 0.92);
    backdrop-filter: blur(12px);
}

html.dark .course-card-cover {
    border-bottom: 1px solid var(--color-border);
}

html.dark .google-btn {
    background: var(--color-surface);
    border-color: var(--color-border);
    color: var(--color-text);
}

html.dark .google-btn:hover {
    background: var(--color-gray-100);
    border-color: var(--color-gray-300);
    color: var(--color-text);
}

html.dark .markdown-body img {
    border-radius: var(--radius-md);
    border: 1px solid var(--color-border);
}

html.dark .markdown-body table th {
    background: var(--color-gray-100);
}

html.dark .markdown-body blockquote {
    border-left-color: var(--color-gray-300);
    color: var(--color-text-secondary);
}

html.dark .course-topbar {
    background: rgba(26, 27, 30, 0.92);
    backdrop-filter: blur(12px);
}

/* ========== Sidebar Progress Bar ========== */
.sidebar-progress {
    padding: var(--space-3) var(--space-5);
    border-bottom: 1px solid var(--color-border);
}

.sidebar-progress-bar {
    height: 4px;
    background: var(--color-gray-200);
    border-radius: 2px;
    overflow: hidden;
    margin-bottom: var(--space-1);
}

.sidebar-progress-fill {
    height: 100%;
    background: var(--color-success);
    border-radius: 2px;
    transition: width 0.3s ease;
}

.sidebar-progress-text {
    font-size: 0.75rem;
    color: var(--color-text-muted);
}

/* ========== Lesson Checkmarks ========== */
.lesson-link {
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.lesson-check {
    flex-shrink: 0;
    width: 16px;
    height: 16px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.lesson-check-empty {
    width: 14px;
    height: 14px;
    border: 1.5px solid var(--color-gray-300);
    border-radius: 50%;
}

.lesson-check-done {
    color: var(--color-success);
}

.chapter-badge-done {
    margin-left: auto;
    color: var(--color-success);
    font-size: 0.75rem;
    display: inline-flex;
    align-items: center;
    gap: 2px;
}

/* ========== Mark Complete Button ========== */
.mark-complete-section {
    display: flex;
    justify-content: center;
    padding: var(--space-6) 0 var(--space-2);
}

.btn-mark-complete {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    padding: 0.5rem 1.25rem;
    font-size: 0.875rem;
    font-weight: 500;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-surface);
    color: var(--color-text-secondary);
    cursor: pointer;
    transition: all var(--transition);
}

.btn-mark-complete:hover {
    border-color: var(--color-success);
    color: var(--color-success);
    background: var(--color-success-light);
}

.btn-mark-complete.completed {
    border-color: var(--color-success);
    color: var(--color-success);
    background: var(--color-success-light);
}

/* ========== Course Card Progress ========== */
.course-card-progress {
    padding: 0 var(--space-5) var(--space-4);
}

.course-card-progress-bar {
    height: 3px;
    background: var(--color-gray-200);
    border-radius: 2px;
    overflow: hidden;
    margin-bottom: var(--space-1);
}

.course-card-progress-fill {
    height: 100%;
    background: var(--color-success);
    border-radius: 2px;
    transition: width 0.3s ease;
}

.course-card-progress-text {
    font-size: 0.6875rem;
    color: var(--color-text-muted);
}