:root {
    /* Light Theme (Default) */
    --bg-primary: #f8fafc;
    --bg-secondary: #ffffff;
    --bg-glass: rgba(255, 255, 255, 0.7);
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --accent-primary: #3b82f6;
    --accent-hover: #2563eb;
    --gradient-start: #3b82f6;
    --gradient-end: #8b5cf6;
    --border-color: rgba(0, 0, 0, 0.08);
    --shadow-soft: 0 10px 25px -5px rgba(0, 0, 0, 0.05), 0 8px 10px -6px rgba(0, 0, 0, 0.01);

    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;

    --radius-sm: 0.5rem;
    --radius-md: 0.75rem;
    --radius-lg: 1rem;

    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
}

[data-theme="dark"] {
    /* Dark Theme */
    --bg-primary: #1e1e1e;
    --bg-secondary: #2d2d2d;
    --bg-glass: rgba(30, 30, 30, 0.75);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --border-color: rgba(255, 255, 255, 0.1);
    --shadow-soft: 0 10px 25px -5px rgba(0, 0, 0, 0.3), 0 8px 10px -6px rgba(0, 0, 0, 0.2);
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

#app-root {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* Typography */
h1,
h2,
h3,
h4,
h5,
h6 {
    font-weight: 600;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

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

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

.gradient-text {
    background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    font-weight: 700;
}

/* Header & Nav */
.app-header {
    position: fixed;
    top: var(--spacing-md);
    left: var(--spacing-md);
    right: var(--spacing-md);
    background-color: var(--bg-glass);
    backdrop-filter: blur(12px);
    border: 1px solid var(--border-color);
    border-radius: 9999px;
    padding: var(--spacing-md) var(--spacing-xl);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    z-index: 100;
    box-shadow: var(--shadow-soft);
    max-width: 1200px;
    margin: 0 auto;
    transition: transform var(--transition-normal);
}

.app-header.header-hidden {
    transform: translateY(calc(-100% - var(--spacing-md)));
}

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

.logo {
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: -0.5px;
}

.logo-icon {
    width: 24px;
    height: 24px;
    background-color: var(--text-primary);
    -webkit-mask: url('./media/web-svg.svg') no-repeat center;
    mask: url('./media/web-svg.svg') no-repeat center;
    -webkit-mask-size: contain;
    mask-size: contain;
    transition: background-color var(--transition-normal);
}

.theme-toggle-btn {
    background: transparent;
    border: none;
    color: var(--text-primary);
    padding: 0.5rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.theme-toggle-btn:hover {
    transform: scale(1.1);
    color: var(--accent-primary);
}

.theme-toggle-btn svg {
    width: 24px;
    height: 24px;
}

[data-theme="dark"] .icon-dark {
    display: none;
}

[data-theme="light"] .icon-light {
    display: none;
}

.breadcrumb-nav {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.breadcrumb-nav.container {
    padding: 130px var(--spacing-xl) 0;
    /* Clear header */
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
}

.breadcrumb-item {
    cursor: pointer;
    transition: color var(--transition-fast);
}

.breadcrumb-item:hover,
.breadcrumb-item.active {
    color: var(--text-primary);
    font-weight: 500;
}

.breadcrumb-separator {
    color: var(--text-secondary);
    opacity: 0.5;
}

/* Main Content */
.app-main {
    flex: 1;
    padding: var(--spacing-lg) var(--spacing-xl) var(--spacing-xl);
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
}

.content-body {
    font-family: source-serif-pro, Georgia, Cambria, "Times New Roman", Times, serif;
    font-size: 20px;
    line-height: 32px;
    font-weight: 400;
    color: rgb(36, 36, 36);
}

[data-theme="dark"] .content-body {
    color: var(--text-primary);
}

.content-body img {
    max-width: 100%;
    min-width: 0;
    height: auto;
}

/* Loading State */
.loading-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 40vh;
    color: var(--text-secondary);
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid rgba(148, 163, 184, 0.2);
    border-radius: 50%;
    border-top-color: var(--accent-primary);
    animation: spin 1s ease-in-out infinite;
    margin-bottom: var(--spacing-md);
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* Grid Layouts */
.grid-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    animation: fadeIn var(--transition-normal);
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Cards */
.card {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    cursor: pointer;
    transition: transform var(--transition-fast), box-shadow var(--transition-fast), border-color var(--transition-fast);
    display: flex;
    flex-direction: column;
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-soft);
    border-color: var(--accent-primary);
}

.card-title {
    font-size: 1.125rem;
    margin-bottom: var(--spacing-sm);
}

.card-description {
    color: var(--text-secondary);
    font-size: 0.9rem;
    flex: 1;
}

.card-meta {
    margin-top: var(--spacing-md);
    font-size: 0.8125rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.badge {
    background: var(--bg-primary);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
    padding: 2px 8px;
    border-radius: 12px;
    font-size: 0.7rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    align-self: flex-start;
    margin-bottom: var(--spacing-sm);
}

.path-badge {
    color: #8b5cf6;
    background: rgba(139, 92, 246, 0.1);
    border-color: rgba(139, 92, 246, 0.2);
}

.track-badge {
    color: #3b82f6;
    background: rgba(59, 130, 246, 0.1);
    border-color: rgba(59, 130, 246, 0.2);
}

/* Module Section */
.module-section {
    margin-bottom: var(--spacing-xl);
    animation: fadeIn var(--transition-normal);
}

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

.module-title {
    font-size: 1.25rem;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.module-desc {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.exercise-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.exercise-item {
    display: flex;
    align-items: center;
    padding: var(--spacing-md);
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.exercise-item:hover {
    box-shadow: var(--shadow-soft);
    border-color: var(--accent-primary);
    transform: translateX(4px);
}

.exercise-icon {
    width: 24px;
    height: 24px;
    margin-right: var(--spacing-md);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-secondary);
}

.exercise-type {
    font-size: 0.65rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-right: var(--spacing-md);
    width: 90px;
}

.exercise-title {
    flex: 1;
    font-weight: 500;
    font-size: 0.95rem;
}

/* Content View */
.content-view {
    padding: var(--spacing-md) 0;
    animation: fadeIn var(--transition-normal);
    max-width: 850px;
    margin: 0 auto;
}

.content-header {
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--border-color);
    text-align: center;
}

.content-header h1 {
    font-size: 2rem;
}

.content-body {
    font-family: 'Source Serif Pro', serif;
    font-size: 1.125rem;
    color: var(--text-primary);
    line-height: 1.8;
}

/* Markdown Styles */
.content-body p {
    margin-bottom: var(--spacing-md);
}

.content-body h2,
.content-body h3 {
    font-family: 'Inter', sans-serif;
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
}

.content-body ul,
.content-body ol {
    margin-bottom: var(--spacing-md);
    padding-left: var(--spacing-xl);
}

.content-body li {
    margin-bottom: var(--spacing-sm);
}

.content-body blockquote {
    border-left: 4px solid var(--accent-primary);
    padding-left: var(--spacing-md);
    margin: var(--spacing-md) 0;
    color: var(--text-secondary);
    background: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    font-style: italic;
    border-top: 1px solid var(--border-color);
    border-right: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}

.content-body pre {
    background-color: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: var(--radius-sm);
    overflow-x: auto;
    margin-bottom: var(--spacing-md);
    border: 1px solid var(--border-color);
    font-family: 'Inter', monospace;
    font-size: 0.9rem;
}

.content-body code {
    font-family: monospace;
    background-color: var(--bg-secondary);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 0.9em;
    color: var(--accent-primary);
    border: 1px solid var(--border-color);
}

.content-body pre code {
    background-color: transparent;
    padding: 0;
    color: inherit;
    border: none;
}

.placeholder-component {
    padding: var(--spacing-md);
    background-color: var(--bg-secondary);
    border: 1px dashed var(--border-color);
    border-radius: var(--radius-md);
    text-align: center;
    color: var(--text-secondary);
    font-family: 'Inter', sans-serif;
    margin: var(--spacing-md) 0;
    font-size: 0.9rem;
}

/* Navigation Buttons */
.nav-buttons {
    display: flex;
    justify-content: space-between;
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--border-color);
}

.nav-btn {
    display: inline-flex;
    align-items: center;
    padding: 0.75rem 1.25rem;
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-weight: 500;
    font-family: 'Inter', sans-serif;
    transition: all var(--transition-fast);
}

.nav-btn:hover {
    background-color: var(--bg-primary);
    border-color: var(--accent-primary);
    color: var(--accent-primary);
}

.nav-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

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

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

/* Back Button */
.back-btn {
    display: inline-flex;
    align-items: center;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    cursor: pointer;
    font-family: 'Inter', sans-serif;
    font-size: 0.875rem;
    font-weight: 500;
    transition: color var(--transition-fast);
}

.back-btn:hover {
    color: var(--accent-primary);
}

.back-btn svg {
    margin-right: 4px;
    width: 20px;
    height: 20px;
}

/* Footer */
.app-footer {
    text-align: center;
    padding: var(--spacing-xl) 0;
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-top: auto;
}

/* Additions for new features */
.video-container {
    position: relative;
    width: 100%;
    padding-bottom: 56.25%;
    /* 16:9 Aspect Ratio */
    height: 0;
    overflow: hidden;
    margin-bottom: var(--spacing-md);
    border-radius: var(--radius-md);
    background-color: #000;
}

.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: none;
}

.checkpoint {
    margin-top: var(--spacing-xl);
    padding: var(--spacing-md) var(--spacing-lg);
    background-color: rgba(59, 130, 246, 0.05);
    border-left: 4px solid var(--accent-primary);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

.checkpoint h4 {
    margin-bottom: var(--spacing-sm);
    color: var(--accent-primary);
    font-size: 1.1rem;
}

/* Basic Syntax Highlighting */
.syn-keyword {
    color: #c678dd;
}

.syn-string {
    color: #98c379;
}

.syn-comment {
    color: #5c6370;
    font-style: italic;
}

.syn-function {
    color: #61afef;
}

.syn-number {
    color: #d19a66;
}

.syn-operator {
    color: #56b6c2;
}

[data-theme="light"] .syn-keyword {
    color: #a626a4;
}

[data-theme="light"] .syn-string {
    color: #50a14f;
}

[data-theme="light"] .syn-comment {
    color: #a0a1a7;
}

[data-theme="light"] .syn-function {
    color: #4078f2;
}

[data-theme="light"] .syn-number {
    color: #986801;
}

[data-theme="light"] .syn-operator {
    color: #383a42;
}

/* Quizzes */
.quiz-question {
    margin-bottom: var(--spacing-xl);
    background: var(--bg-secondary);
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.quiz-answers {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
}

.quiz-answer-label {
    display: flex;
    align-items: flex-start;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.quiz-answer-label:hover {
    border-color: var(--accent-primary);
}

.quiz-answer-label input {
    margin-top: 5px;
    margin-right: var(--spacing-md);
}

.quiz-feedback {
    margin-top: var(--spacing-md);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: 0.95rem;
    display: none;
}

.quiz-feedback.correct {
    display: block;
    background-color: rgba(34, 197, 94, 0.1);
    border-left: 4px solid #22c55e;
}

.quiz-feedback.incorrect {
    display: block;
    background-color: rgba(239, 68, 68, 0.1);
    border-left: 4px solid #ef4444;
}

/* Project Tasks */
.task-item {
    display: flex;
    align-items: flex-start;
    margin-bottom: var(--spacing-sm);
}

.task-item input[type="checkbox"] {
    margin-top: 6px;
    margin-right: var(--spacing-sm);
    width: 18px;
    height: 18px;
    cursor: pointer;
}

.task-item label {
    flex: 1;
    cursor: pointer;
}


/* Responsiveness */
@media (max-width: 768px) {
    .app-header {
        padding: var(--spacing-sm) var(--spacing-md);
        top: var(--spacing-sm);
        left: var(--spacing-sm);
        right: var(--spacing-sm);
    }

    .breadcrumb-nav.container {
        padding: 80px var(--spacing-md) 0;
    }

    .app-main {
        padding: var(--spacing-md);
    }

    .content-view {
        padding: 0;
    }

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

    .content-header h1 {
        font-size: 1.5rem;
    }

    .exercise-type {
        display: none;
        /* hide type badge on mobile for space */
    }
}