/*
 * AI LABS CSS FRAMEWORK
 *
 * This stylesheet is based on the AI Labs Style Guide (web/STYLE.html)
 * AICODE-NOTE: Keep in sync with web/STYLE.html which is the source of truth.
 *
 * Design Principles:
 * - Bold & Confident: Strong colors and clear hierarchy
 * - Classic & Refined: Serif typography for content, sans-serif for UI
 * - Warm & Inviting: Sepia-toned highlights and warm backgrounds
 * - Clear Focus: Red accents guide attention to important actions
 * - Progressive Feedback: Visual states show completion and progress
 */

/* =============================================================================
   CSS RESET
   ============================================================================= */

*, *::before, *::after {
    box-sizing: border-box;
}

* {
    margin: 0;
    padding: 0;
}

html {
    line-height: 1.5;
}

html, body {
    height: 100%;
}

body {
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img, picture, video, canvas, svg {
    display: block;
    max-width: 100%;
}

input, button, textarea, select {
    font: inherit;
}

p, h1, h2, h3, h4, h5, h6 {
    overflow-wrap: break-word;
}

/* =============================================================================
   DESIGN TOKENS (CSS VARIABLES)
   ============================================================================= */

:root {
    --color-white: #FFFFFF;
    --color-black: #000000;

    --color-text-main: #222222;
    --color-text-mid: #444444;
    --color-text-muted: #777777;
    --color-text-highlight: #586e75;
    --color-text-footer: #888888;

    --color-red-main: #cd2e29;
    --color-red-hover: #b22a25;
    --color-red-bright: #e63946;
    --color-red-light: #fff5f5;
    --color-blue-main: #1f76b6;
    --color-green-main: #128e5c;
    --color-green-bright: #16a34a;
    --color-green-light: #f0fdf4;
    --color-green-badge: #d1fae5;

    --color-light-gray: #FAFAFA;
    --color-border: #CCCCCC;
    --color-background-highlight: #fdf6e3;
    --color-background-demo: #EDEDED;
    --color-overlay-bg: rgba(0, 0, 0, 0.6);

    --radius-card: 12px;
    --radius-element: 8px;
    --radius-small: 6px;
    --radius-inline: 4px;

    --shadow-modal: 0 10px 40px rgba(0, 0, 0, 0.3);

    --transition-fast: all 0.2s ease;
    --transition-slow: all 0.5s ease;

    --nav-gap: 1rem;
    --icon-size: 1.25em;
}

/* =============================================================================
   BASE ELEMENT STYLES
   ============================================================================= */

body {
    min-height: 100vh;
    font-family: -apple-system-ui-serif, ui-serif, "Georgia", serif;
    background-color: var(--color-light-gray);
    color: var(--color-text-main);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
}

/* Typography Hierarchy */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    color: var(--color-text-main);
}

h1 {
    font-size: 2.25rem;
    line-height: 2.5rem;
    margin-bottom: 1rem;
}

h2 {
    font-size: 1.875rem;
    line-height: 2.25rem;
    margin-bottom: 0.75rem;
}

h3 {
    font-size: 1.5rem;
    line-height: 2rem;
    margin-bottom: 0.5rem;
}

/* Navigation uses sans-serif */
nav {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

/* Links */
a {
    color: var(--color-red-main);
    text-decoration: none;
    border-bottom: 1px solid transparent;
    transition: border-color 0.2s ease;
}

a:hover {
    border-bottom: 1px solid var(--color-red-main);
}

/* Lists */
ul, ol {
    margin: 1em 0;
    padding-left: 2em;
    line-height: 1.8;
    color: var(--color-text-mid);
}

ul {
    list-style-type: disc;
}

ul ul {
    list-style-type: circle;
    margin: 0.5em 0;
}

ol {
    list-style-type: decimal;
}

ol ol {
    list-style-type: lower-alpha;
    margin: 0.5em 0;
}

ul ol {
    list-style-type: lower-alpha;
    margin: 0.5em 0;
}

ol ul {
    list-style-type: circle;
    margin: 0.5em 0;
}

li {
    margin-bottom: 0.5em;
    padding-left: 0.25em;
}

li:last-child {
    margin-bottom: 0;
}

li li {
    margin-bottom: 0.25em;
}

/* Inline code */
code {
    background-color: var(--color-background-demo);
    padding: 0.2em 0.5em;
    border-radius: var(--radius-inline);
    font-family: Menlo, Monaco, monospace;
    font-size: 0.9em;
}

/* Code blocks */
pre {
    background: var(--color-background-demo);
    padding: 0.75em;
    border-radius: var(--radius-small);
    overflow-x: auto;
    font-family: Menlo, Monaco, monospace;
    font-size: 1em;
}

pre code {
    background: none;
    padding: 0;
    border-radius: 0;
}

/* =============================================================================
   LAYOUT SYSTEM
   ============================================================================= */

/* Containers */
.page-container {
    max-width: 56rem;
    margin: 0 auto;
    padding: 1.75rem 1.25rem;
    flex: 1;
    background-color: var(--color-white);
    box-shadow: 0 0 0 100vw var(--color-white);
    clip-path: inset(0 -100vw);
}

.container-1400 {
    max-width: 1400px;
    margin: 0 auto;
    padding: 1rem 1.25rem;
}

/* Flexbox System */
.flex {
    display: flex;
}

.inline-flex { display: inline-flex; }
.flex-wrap { flex-wrap: wrap; }
.items-start { align-items: flex-start; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.justify-center { justify-content: center; }
.flex-1 { flex: 1 1 0%; }
.flex-shrink-0 { flex-shrink: 0; }

.flex-end-row {
    display: flex;
    justify-content: flex-end;
    gap: 0.75em;
}

/* Grid System */
.grid {
    display: grid;
}

.grid-cols-1 {
    grid-template-columns: repeat(1, minmax(0, 1fr));
}

/* Display Utilities */
.block { display: block; }
.hidden { display: none; }

/* Gap Utilities */
.gap-2 { gap: 0.5rem; }
.gap-3 { gap: 0.75rem; }
.gap-4 { gap: 1rem; }
.gap-5 { gap: 1.25rem; }
.gap-6 { gap: 1.5rem; }

/* Spacing Stack Utilities */
.space-y-2 > * + * { margin-top: 0.5rem; }
.space-y-3 > * + * { margin-top: 0.75rem; }
.space-y-4 > * + * { margin-top: 1rem; }
.space-y-5 > * + * { margin-top: 1.25rem; }
.space-y-6 > * + * { margin-top: 1.5rem; }
.space-y-8 > * + * { margin-top: 2rem; }

/* Margin Utilities */
.mx-auto { margin-left: auto; margin-right: auto; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-3 { margin-bottom: 0.75rem; }
.mb-4 { margin-bottom: 1rem; }
.mb-6 { margin-bottom: 1.5rem; }
.mb-8 { margin-bottom: 2rem; }
.mb-12 { margin-bottom: 3rem; }
.mb-16 { margin-bottom: 4rem; }
.mb-1em { margin-bottom: 1em; }
.mb-2em { margin-bottom: 2em; }
.mt-2em { margin-top: 2em; }
.mt-3em { margin-top: 3em; }

/* Padding Utilities */
.px-3 { padding-left: 0.75rem; padding-right: 0.75rem; }
.px-5 { padding-left: 1.25rem; padding-right: 1.25rem; }
.py-7 { padding-top: 1.75rem; padding-bottom: 1.75rem; }
.py-8 { padding-top: 2rem; padding-bottom: 2rem; }
.py-10 { padding-top: 2.5rem; padding-bottom: 2.5rem; }

/* Width Utilities */
.w-full { width: 100%; }
.max-w-md { max-width: 28rem; }
.max-w-lg { max-width: 32rem; }
.max-w-4xl { max-width: 56rem; }
.max-w-6xl { max-width: 72rem; }

/* Overflow */
.overflow-y-auto { overflow-y: auto; }

/* =============================================================================
   COMPONENT LAYER
   ============================================================================= */

/* Page Header Component */
.page-header {
    background-color: var(--color-light-gray);
    border-bottom: 1px solid var(--color-red-main);
}

.page-header-container {
    max-width: 72rem;
    margin: 0 auto;
    padding: 2rem 1.25rem;
}

.page-title {
    font-size: 2.5em;
    margin-bottom: 0.5rem;
}

.page-subtitle {
    color: var(--color-text-mid);
    font-size: 1.05em;
}

/* Form Components */
input[type="text"],
input[type="email"],
input[type="password"],
textarea {
    padding: 0.5rem 0.75rem;
    transition: var(--transition-fast);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-small);
    background: var(--color-white);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

input[type="text"]:focus,
input[type="email"]:focus,
input[type="password"]:focus,
textarea:focus {
    outline: none;
    border-color: var(--color-red-main);
}

textarea {
    resize: vertical;
    font-family: Menlo, Monaco, monospace;
}

.textarea-code {
    width: 100%;
    font-family: Menlo, Monaco, monospace;
    font-size: 0.9em;
    padding: 0.75em;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-small);
    resize: vertical;
    background-color: var(--color-white);
    line-height: 1.5;
}

label {
    display: block;
    margin-bottom: 0.375rem;
    font-weight: 500;
    color: var(--color-text-mid);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 0.9em;
}

/* Button Components */
button[type="submit"],
.btn-primary,
.btn-secondary {
    padding: 0.5rem 1rem;
    font-weight: 600;
    font-size: 0.95em;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    border-radius: var(--radius-small);
    transition: var(--transition-fast);
    cursor: pointer;
    border-bottom: none;
    text-decoration: none;
}

button[type="submit"]:disabled,
.btn-primary:disabled,
.btn-secondary:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

button[type="submit"]:focus-visible,
.btn-primary:focus-visible,
.btn-secondary:focus-visible {
    outline: 2px solid var(--color-red-main);
    outline-offset: 2px;
}

button[type="submit"],
.btn-primary {
    background-color: var(--color-red-main);
    color: var(--color-white);
    border: none;
}

button[type="submit"]:hover:not(:disabled),
.btn-primary:hover:not(:disabled) {
    background-color: var(--color-red-hover);
    border-bottom: none;
}

.btn-secondary {
    background-color: var(--color-background-demo);
    color: var(--color-text-main);
    border: 1px solid var(--color-border);
}

.btn-secondary:hover:not(:disabled) {
    background-color: var(--color-light-gray);
    border-color: var(--color-text-muted);
    border-bottom: none;
}

/* Card Components */
.content-card {
    padding: 1.5rem;
    background: var(--color-white);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-card);
}

.payment-confirm-card {
    max-width: 42rem;
}

.purchases-table-wrapper {
    overflow-x: auto;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-card);
    background: var(--color-white);
}

.purchases-table {
    width: 100%;
    border-collapse: collapse;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 0.95em;
}

.purchases-table th,
.purchases-table td {
    padding: 0.75rem 0.875rem;
    text-align: left;
    border-bottom: 1px solid var(--color-border);
}

.purchases-table th {
    background-color: var(--color-light-gray);
    font-weight: 700;
}

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

.purchase-keys-block {
    padding: 0.125rem 0 0;
}

.purchase-keys-table-cell {
    padding-top: 0.5rem;
    background: var(--color-white);
}

.purchase-keys-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 0.75rem;
    margin-bottom: 0.875rem;
}

.purchase-keys-title {
    margin: 0 0 0.2rem;
    font-size: 1rem;
}

.purchase-keys-summary {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 0.85rem;
}

.purchase-key-list {
    display: grid;
    gap: 0.5rem;
}

.purchase-key-row {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 0.875rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-element);
    background: var(--color-light-gray);
}

.purchase-key-code {
    flex: 1 1 auto;
    min-width: 0;
    overflow-wrap: anywhere;
    font-family: Menlo, Monaco, monospace;
    font-size: 0.9rem;
    letter-spacing: 0.04em;
}

.purchase-key-actions {
    display: flex;
    align-items: center;
    gap: 0.625rem;
    flex: 0 0 auto;
}

.purchase-key-status {
    flex: 0 0 auto;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 0.8rem;
    font-weight: 600;
    white-space: nowrap;
}

.purchase-key-status--claimed {
    color: var(--color-green-main);
}

.purchase-key-status--available {
    color: var(--color-text-muted);
}

.purchase-key-copy-btn,
.purchase-key-copy-all-btn {
    padding: 0.4rem 0.7rem;
    font-size: 0.82rem;
    line-height: 1.2;
}

.purchase-key-copy-btn.is-copied,
.purchase-key-copy-all-btn.is-copied {
    border-color: var(--color-green-main);
    color: var(--color-green-main);
}

.purchase-keys-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 0.75rem;
    margin-top: 1rem;
    padding-top: 0.875rem;
    border-top: 1px solid var(--color-border);
}

.purchase-keys-footer-note {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 0.82rem;
    line-height: 1.5;
}

.payment-confirm-header {
    display: flex;
    align-items: center;
    gap: 0.625rem;
    margin-bottom: 0.75rem;
}

.payment-confirm-header h3 {
    margin: 0;
}

.payment-spinner {
    width: 1rem;
    height: 1rem;
    border-radius: 999px;
    border: 2px solid var(--color-border);
    border-top-color: var(--color-red-main);
    animation: payment-spin 0.9s linear infinite;
}

@keyframes payment-spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

/* Code Block Wrapper */
.code-block-wrapper {
    background-color: var(--color-background-demo);
    border-radius: var(--radius-element);
    margin: 1.5em 0;
    overflow-x: auto;
    padding: 0;
}

.code-block-wrapper pre {
    margin: 0;
    font-family: Menlo, Monaco, monospace;
    font-size: 0.9em;
}

/* Module List Component */
.module-list-item {
    display: block;
    padding: 0.625rem;
    margin-bottom: 0.625rem;
    cursor: pointer;
    transition: background-color 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-element);
    background: var(--color-white);
    text-decoration: none;
    color: inherit;
}

.module-list-item:hover {
    border-color: var(--color-red-main);
    background-color: var(--color-red-light);
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.08);
}

.module-list-item.active {
    border-color: var(--color-green-main);
    background-color: var(--color-green-light);
    box-shadow: 0 0 0 1px var(--color-green-main);
}

.module-list-item.completed {
    background-color: var(--color-background-demo);
    border-color: var(--color-text-muted);
    opacity: 0.7;
}

.module-list-item.locked {
    opacity: 0.6;
}

.module-title {
    font-weight: 600;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 0.95em;
}

.module-title-locked {
    font-weight: 600;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 0.95em;
    color: var(--color-text-muted);
}

.module-description {
    color: var(--color-text-muted);
    font-size: 0.85em;
    margin: 0;
}

/* Progress Bar Component */
.progress-bar {
    width: 100%;
    background-color: var(--color-background-demo);
    overflow: hidden;
    height: 12px;
    border-radius: 9999px;
}

.progress-bar.progress-bar-small {
    height: 8px;
    border-radius: 4px;
}

.progress-bar.progress-bar-mini {
    height: 6px;
    border-radius: 3px;
}

.progress-fill {
    transition: var(--transition-slow);
    background: linear-gradient(90deg, var(--color-red-main) 0%, var(--color-red-bright) 100%);
    height: 100%;
    border-radius: inherit;
}

/* Badge Component */
.badge {
    display: inline-flex;
    align-items: center;
    padding: 0.125rem 0.625rem;
    font-weight: 600;
    font-size: 0.7em;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    border-radius: 999px;
}

.badge-success,
.badge-primary {
    background-color: var(--color-green-badge);
    color: var(--color-green-main);
    border: 1px solid var(--color-green-main);
}

.badge-gray {
    background-color: var(--color-background-demo);
    color: var(--color-text-muted);
    border: 1px solid var(--color-border);
}

/* Navigation Components */
.nav-link {
    text-decoration: none;
    transition: color 0.2s ease;
    color: var(--color-text-main);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 0.95em;
    border-bottom: 1px solid transparent;
    display: inline-flex;
    align-items: center;
}

.nav-link:hover {
    color: var(--color-red-main);
    border-bottom: 1px solid var(--color-red-main);
}

.nav-icon {
    width: var(--icon-size);
    height: var(--icon-size);
    display: inline-block;
    vertical-align: middle;
    margin-right: 0.4em;
    flex-shrink: 0;
}

.nav-separator {
    width: 1px;
    height: 1.5em;
    background-color: var(--color-border);
}

.nav-container {
    display: flex;
    align-items: center;
    gap: var(--nav-gap);
}

.brand-link {
    font-size: 1.5em;
    font-weight: 700;
    line-height: 1.2;
}

/* Breadcrumb Component */
.breadcrumb-link {
    font-size: 0.85em;
    color: var(--color-text-muted);
    text-decoration: none;
    border-bottom: 1px solid transparent;
    transition: all 0.2s ease;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.breadcrumb-link:hover {
    color: var(--color-red-main);
    border-bottom: 1px solid var(--color-red-main);
}

.breadcrumb-separator {
    color: var(--color-text-muted);
    font-size: 0.85em;
    flex-shrink: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

/* Course Header Components */
.course-header-title {
    font-weight: 600;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    color: var(--color-text-main);
    font-size: 1.1em;
    margin-bottom: 0.75em;
}

.course-title-section {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
}

/* Sidebar Components */
.modules-sidebar {
    background-color: var(--color-light-gray);
    border-right: 1px solid var(--color-border);
    padding: 1.5em;
    overflow-y: auto;
}

.sidebar-max-height {
    max-height: calc(100vh - 8rem);
}

.sidebar-section-header {
    font-size: 0.8em;
    font-weight: 700;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    color: var(--color-text-muted);
    margin: 0;
    font-family: -apple-system, sans-serif;
}

/* Collapsible Sidebar Toggle */
.modules-toggle {
    cursor: pointer;
    transition: color 0.2s ease;
    color: var(--color-text-muted);
    font-size: 0.9em;
    font-weight: normal;
    white-space: nowrap;
    user-select: none;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.modules-toggle:hover {
    color: var(--color-red-main);
}

.modules-toggle-icon {
    display: inline-block;
    transition: transform 0.3s;
}

/* Highlight Box */
.highlight-box {
    border: 1px solid var(--color-border);
    border-radius: var(--radius-card);
    background-color: var(--color-background-highlight);
    padding: 1.25em;
    color: var(--color-text-highlight);
}

/* Content Layout Components */
.content-with-margin-notes {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

/* Section Divider */
.section-divider {
    margin-top: 3em;
    padding-top: 2.5em;
    border-top: 2px solid var(--color-red-main);
}

/* Media Components */
.media-placeholder {
    background: linear-gradient(135deg, #fdf6e3 0%, #f5ebe0 100%);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-card);
    padding: 4em 2em;
    text-align: center;
}

.media-caption {
    color: var(--color-text-mid);
    font-weight: 600;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

/* Resource Card Component */
.resource-title {
    font-weight: 700;
    margin-bottom: 0.5em;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.resource-description {
    color: var(--color-text-mid);
    font-size: 0.95em;
    margin-bottom: 0.75em;
}

/* Course Catalogue */
.courses-list-page {
    max-width: 76rem;
    padding-top: 2.5rem;
    padding-bottom: 2.5rem;
    background: transparent;
    box-shadow: none;
    clip-path: none;
}

.courses-list-header {
    max-width: 42rem;
}

.course-catalog-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.course-catalog-card {
    display: flex;
    align-items: stretch;
    background: var(--color-white);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-card);
    overflow: hidden;
    transition: var(--transition-fast);
}

.course-catalog-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
}

.course-catalog-card--enrolled {
    border: 2px solid var(--color-green-main);
}

.course-catalog-card--available {
    border: 2px solid var(--color-red-main);
    box-shadow: 0 4px 20px rgba(205, 46, 41, 0.08);
}

.course-catalog-card--soon {
    opacity: 0.72;
}

.course-catalog-card__banner {
    width: 12.5rem;
    min-height: 12rem;
    flex-shrink: 0;
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1.25rem;
    border-right: 1px solid var(--color-border);
}

.course-catalog-card__banner--enrolled {
    background: linear-gradient(160deg, #f0fdf4 0%, #dcfce7 100%);
    border-right-color: #c6f0da;
    color: var(--color-green-main);
}

.course-catalog-card__banner--available {
    background: linear-gradient(160deg, #fdf6e3 0%, #f5ebe0 100%);
    border-right-color: #e8d5b7;
    color: var(--color-red-main);
}

.course-catalog-card__banner--soon {
    background: linear-gradient(160deg, #f1f5f9 0%, #e2e8f0 100%);
    color: var(--color-text-muted);
}

.course-catalog-card__badge {
    position: absolute;
    top: 0.75rem;
    left: 0.75rem;
}

.course-catalog-badge-available {
    background-color: var(--color-background-highlight);
    color: var(--color-text-highlight);
    border: 1px solid #d4b896;
}

.course-catalog-card__icon {
    width: 3rem;
    height: 3rem;
    opacity: 0.55;
}

.course-catalog-card__body {
    flex: 1 1 auto;
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 0.6rem;
    padding: 1.1rem 1.25rem;
    min-width: 0;
}

.course-catalog-card__title {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-weight: 700;
    font-size: 1.05rem;
    color: var(--color-text-main);
}

.course-catalog-card__description {
    color: var(--color-text-mid);
    font-size: 0.92rem;
    line-height: 1.6;
    margin: 0;
}

.course-catalog-card__meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.9rem;
    color: var(--color-text-muted);
    font-size: 0.82rem;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.course-catalog-card__progress {
    margin-top: 0.1rem;
}

.course-catalog-card__progress-head {
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    margin-bottom: 0.375rem;
    color: var(--color-text-muted);
    font-size: 0.8rem;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.course-catalog-card__progress-fill {
    background: linear-gradient(90deg, var(--color-green-main) 0%, var(--color-green-bright) 100%);
}

.course-catalog-card__actions {
    width: 13rem;
    flex-shrink: 0;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: flex-end;
    gap: 0.55rem;
    padding: 1.1rem 1.25rem;
}

.course-catalog-card__actions .btn-primary,
.course-catalog-card__actions .btn-secondary {
    white-space: nowrap;
}

.course-catalog-card__cta--success {
    background-color: var(--color-green-main);
}

.course-catalog-card__cta--success:hover:not(:disabled) {
    background-color: #0f7a4f;
}

.course-catalog-card__action-hint {
    margin: 0;
    color: var(--color-text-muted);
    font-size: 0.8rem;
    line-height: 1.5;
    text-align: right;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.course-catalog-note {
    margin-top: 2rem;
    padding: 1rem 1.25rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-element);
    background: var(--color-white);
    color: var(--color-text-muted);
    font-size: 0.92rem;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.course-catalog-note p {
    margin: 0;
}

/* =============================================================================
   COURSE OVERVIEW COMPONENTS
   ============================================================================= */

.course-syllabus-list {
    counter-reset: syllabus-item;
}

.course-syllabus-list .syllabus-item {
    counter-increment: syllabus-item;
}

.syllabus-item {
    display: flex;
    gap: 0.75em;
    padding: 0.625em 0;
    border-bottom: 1px solid var(--color-border);
    align-items: flex-start;
}

.syllabus-item:last-child {
    border-bottom: none;
}

.syllabus-num {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 0.75em;
    font-weight: 700;
    color: var(--color-text-muted);
    min-width: 1.5em;
    margin-top: 0.15em;
}

.course-syllabus-list .syllabus-num::before {
    content: counter(syllabus-item, decimal-leading-zero);
}

.syllabus-title {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 0.9em;
    color: var(--color-text-mid);
    flex: 1;
}

.syllabus-duration {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 0.75em;
    color: var(--color-text-muted);
    white-space: nowrap;
}

.purchase-block {
    border: 1.5px solid var(--color-border);
    border-radius: var(--radius-element);
    overflow: hidden;
}

.purchase-block-header {
    padding: 0.875rem 1rem;
    background: var(--color-white);
}

.purchase-block-title {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-weight: 700;
    font-size: 0.95em;
    color: var(--color-text-main);
    margin-bottom: 0.2em;
}

.purchase-block-desc {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 0.82em;
    color: var(--color-text-muted);
    line-height: 1.5;
}

.activate-block {
    border: 1.5px solid var(--color-border);
    border-radius: var(--radius-element);
    padding: 0.875rem 1rem;
    background: var(--color-white);
}

.activate-block-title {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-weight: 700;
    font-size: 0.95em;
    color: var(--color-text-main);
    margin-bottom: 0.2em;
}

.activate-block-desc {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 0.82em;
    color: var(--color-text-muted);
    margin-bottom: 0.75em;
    line-height: 1.5;
}

.key-input {
    font-family: Menlo, Monaco, monospace;
    font-size: 0.9em;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    padding: 0.5rem 0.75rem;
    border: 1.5px solid var(--color-border);
    border-radius: var(--radius-small);
    background: var(--color-white);
    width: 100%;
}

.key-input:focus {
    outline: none;
    border-color: var(--color-red-main);
}

.key-input::placeholder {
    text-transform: none;
    letter-spacing: 0;
    opacity: 0.55;
}

.divider-text {
    display: flex;
    align-items: center;
    gap: 0.75em;
    color: var(--color-text-muted);
    font-size: 0.85em;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.divider-text::before,
.divider-text::after {
    content: "";
    flex: 1;
    height: 1px;
    background: var(--color-border);
}

.course-lock-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.4em;
    background: var(--color-background-demo);
    border: 1px solid var(--color-border);
    border-radius: 999px;
    padding: 0.2em 0.75em;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 0.75em;
    font-weight: 600;
    color: var(--color-text-muted);
    margin-bottom: 1em;
}

/* =============================================================================
   UTILITY CLASSES
   ============================================================================= */

/* Text Color Utilities */
.text-main { color: var(--color-text-main); }
.text-mid { color: var(--color-text-mid); }
.text-muted { color: var(--color-text-muted); }
.text-highlight { color: var(--color-text-highlight); }
.text-footer { color: var(--color-text-footer); }
.text-red { color: var(--color-red-main); }
.text-green { color: var(--color-green-main); }
.text-blue { color: var(--color-blue-main); }
.text-white { color: var(--color-white); }

/* Font Family Utilities */
.font-sans { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; }
.font-serif { font-family: ui-serif, Georgia, serif; }
.font-mono { font-family: Menlo, Monaco, monospace; }

/* Font Weight Utilities */
.font-semibold { font-weight: 600; }
.font-bold { font-weight: 700; }

/* Font Size Utilities */
.text-xs { font-size: 0.7em; }
.text-sm { font-size: 0.85em; }
.text-base { font-size: 0.95em; }
.text-lg { font-size: 1.05em; }
.text-xl { font-size: 1.1em; }

/* Text Alignment */
.text-center { text-align: center; }
.text-right { text-align: right; }
.whitespace-nowrap { white-space: nowrap; }
.no-underline { text-decoration: none; }

/* Semantic Content Classes */
.section-header {
    font-weight: 700;
    margin-bottom: 0.75em;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.subsection-header {
    font-weight: 700;
    margin-top: 1.25em;
    margin-bottom: 0.5em;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 1.1em;
}

.card-description {
    color: var(--color-text-mid);
    margin-bottom: 1.25em;
}

.content-text {
    color: var(--color-text-mid);
    line-height: 1.7;
}

.subtle-divider {
    padding: 0.5em;
    text-align: center;
    color: var(--color-text-muted);
    font-size: 0.85em;
    font-style: italic;
}

/* Content Styling Helpers */
.heading-with-tight-margin {
    margin-bottom: 0.3em;
}

.heading-with-normal-margin {
    margin-bottom: 0.75em;
}

.page-content-text {
    color: var(--color-text-mid);
    font-size: 1.05em;
    line-height: 1.6;
}

/* =============================================================================
   MODAL COMPONENT
   ============================================================================= */

#doc-modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--color-overlay-bg);
    z-index: 1000;
    display: none;
    opacity: 0;
    transition: opacity 0.2s ease;
}

#doc-modal.is-open {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
}

#doc-modal.is-visible {
    opacity: 1;
}

#doc-modal > div {
    background: var(--color-white);
    border-radius: var(--radius-card);
    max-width: 48rem;
    width: 100%;
    max-height: 85vh;
    display: flex;
    flex-direction: column;
    box-shadow: var(--shadow-modal);
}

#doc-modal > div > div:first-child {
    padding: 1.5rem;
    border-bottom: 1px solid var(--color-border);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

#doc-modal > div > div:first-child h2 {
    margin: 0;
    font-size: 1.5rem;
}

#doc-modal > div > div:first-child button {
    background: none;
    border: none;
    font-size: 2rem;
    line-height: 1;
    cursor: pointer;
    color: var(--color-text-muted);
    padding: 0;
    width: 2rem;
    height: 2rem;
}

#doc-modal > div > div:first-child button:hover {
    color: var(--color-text-main);
}

#doc-modal > div > div:nth-child(2) {
    padding: 1.5rem;
    overflow-y: auto;
    flex: 1;
}

#doc-modal > div > div:last-child {
    padding: 1.5rem;
    border-top: 1px solid var(--color-border);
    display: flex;
    justify-content: flex-end;
}

/* =============================================================================
   FOOTER
   ============================================================================= */

footer {
    margin-top: auto;
    padding: 2em 1.25rem;
    border-top: 2px solid var(--color-red-main);
    text-align: center;
    color: var(--color-text-footer);
}

footer p {
    margin: 0;
}

/* =============================================================================
   RESPONSIVE DESIGN
   ============================================================================= */

/* Desktop sidebar (769px and above) */
@media (min-width: 769px) {
    .modules-sidebar {
        width: 320px;
        transition: width 0.3s ease, opacity 0.3s ease, padding 0.3s ease;
        overflow-y: auto;
        flex-shrink: 0;
    }

    .modules-sidebar.collapsed {
        width: 0;
        opacity: 0;
        border-right: none;
        padding: 0;
        overflow: hidden;
    }

    .sidebar-overlay {
        display: none !important;
    }

    .md\:grid-cols-2 {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
}

/* Medium screens */
@media (max-width: 1024px) and (min-width: 769px) {
    :root {
        --nav-gap: 0.75rem;
    }
}

/* Margin notes layout on wide screens */
@media (min-width: 1200px) {
    .content-with-margin-notes {
        display: grid;
        grid-template-columns: minmax(0, 50em) 280px;
        column-gap: 2em;
        row-gap: 1.5rem;
        align-items: start;
    }

    .content-with-margin-notes > * {
        grid-column: 1;
    }

    .content-with-margin-notes .highlight-box {
        grid-column: 2;
        grid-row: var(--note-row, auto);
        align-self: end;
        margin: 0;
        padding: 1em 0;
        max-width: 15rem;
        font-size: 0.85em;
        line-height: 1.6;
        background-color: transparent;
        border: none;
        border-left: 3px solid var(--color-red-main);
        border-radius: 0;
        padding-left: 1em;
        color: var(--color-text-muted);
    }
}

/* Mobile sidebar (768px and below) */
@media (max-width: 768px) {
    :root {
        --nav-gap: 0.25rem;
        --icon-size: 1.5em;
    }

    h1 {
        font-size: 1.75rem;
        line-height: 2rem;
    }

    h2 {
        font-size: 1.5rem;
        line-height: 1.75rem;
    }

    .page-title {
        font-size: 2em;
    }

    /* Mobile sidebar - centered modal */
    .modules-sidebar {
        position: fixed;
        top: 50%;
        left: 50%;
        transform: translate(-50%, -50%) scale(0.9);
        width: calc(100% - 2.5rem);
        max-width: 400px;
        max-height: 80vh;
        z-index: 1000;
        opacity: 0;
        pointer-events: none;
        transition: opacity 0.3s ease, transform 0.3s ease;
        box-shadow: var(--shadow-modal);
        border-radius: var(--radius-card);
        border-right: none !important;
        overflow-y: auto;
    }

    .modules-sidebar:not(.mobile-open) {
        padding: 0;
        overflow: hidden;
    }

    .modules-sidebar.mobile-open {
        transform: translate(-50%, -50%) scale(1);
        opacity: 1;
        pointer-events: auto;
    }

    /* Sidebar overlay */
    .sidebar-overlay {
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background-color: var(--color-overlay-bg);
        z-index: 999;
        opacity: 0;
        pointer-events: none;
        transition: opacity 0.3s ease;
    }

    .sidebar-overlay.active {
        opacity: 1;
        pointer-events: auto;
    }

    /* Mobile course header */
    .course-title-section {
        flex-wrap: nowrap;
        gap: 0.5rem;
    }

    .course-header-title {
        font-size: 0.95em;
        margin: 0;
        white-space: nowrap;
        flex-shrink: 0;
    }

    .modules-toggle {
        font-size: 0.8em;
        flex-shrink: 0;
    }

    .nav-separator {
        display: none;
    }

    .nav-link {
        padding: 0.5rem;
        border-bottom: none;
    }

    .nav-link:hover {
        color: var(--color-red-main);
        border-bottom: none;
    }

    .nav-icon {
        margin: 0;
    }

    .purchases-table {
        min-width: 38rem;
        font-size: 0.9em;
    }

    .purchase-key-row {
        align-items: flex-start;
        flex-direction: column;
    }

    .purchase-key-actions,
    .purchase-keys-footer {
        align-items: flex-start;
        flex-direction: column;
    }

    .purchase-key-status {
        white-space: normal;
    }

    .courses-list-page {
        padding-top: 2rem;
        padding-bottom: 2rem;
    }

    .course-catalog-card {
        flex-direction: column;
    }

    .course-catalog-card__banner {
        width: 100%;
        min-height: 8rem;
        border-right: none;
        border-bottom: 1px solid var(--color-border);
    }

    .course-catalog-card__actions {
        width: 100%;
        align-items: flex-start;
        padding-top: 0;
    }

    .course-catalog-card__action-hint {
        text-align: left;
    }
}