/* Base styles */
body {
    font-family: 'Avenir Book', Avenir, 'Sarabun', 'IBM Plex Sans Thai', 'Noto Sans Thai', -apple-system, BlinkMacSystemFont, 'Segoe UI', Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f7f7f4;
    color: #24313f;
    line-height: 1.75;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

header {
    background-color: #253241;
    color: #fff;
    padding: 1.25rem 1rem;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

header h1 {
    margin: 0;
    font-size: 1.8rem;
    font-weight: 700;
}

header h1 a {
    color: #fff;
    text-decoration: none;
}

header h1 a:hover {
    color: #61dafb;
}

header p {
    font-size: 1rem;
    margin-top: 0.5rem;
    opacity: 0.9;
}

footer {
    text-align: center;
    padding: 1.5rem 0;
    background-color: #2c3e50;
    color: #fff;
    font-size: 0.9rem;
    margin-top: auto;
    box-shadow: 0 -2px 4px rgba(0,0,0,0.1);
}

footer p {
    margin: 0.5rem 0;
}

footer a {
    color: #61dafb;
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

.container {
    max-width: 860px;
    margin: 0 auto;
    padding: 1rem;
    flex: 1;
}

.home {
    max-width: 1120px;
}

.home-intro {
    max-width: 780px;
    margin: 1.5rem auto 2rem;
}

.home-intro h2 {
    font-size: 2rem;
    line-height: 1.25;
    margin: 0 0 0.75rem;
    color: #1f2d3a;
}

.search-box {
    display: block;
    margin-top: 1.5rem;
}

.search-box span {
    display: block;
    font-weight: 700;
    margin-bottom: 0.35rem;
}

.search-box input {
    width: 100%;
    border: 1px solid #cdd7e1;
    border-radius: 6px;
    font: inherit;
    padding: 0.75rem 0.9rem;
    background-color: #fff;
}

.search-results {
    list-style: none;
    padding: 0;
    margin: 0.75rem 0 0;
    border: 1px solid #dce3ea;
    border-radius: 6px;
    background: #fff;
    overflow: hidden;
}

.search-results a {
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    padding: 0.65rem 0.9rem;
    text-decoration: none;
    color: #1f2d3a;
}

.search-results a:hover {
    background-color: #f7f9fb;
}

.search-results span {
    color: #607080;
    font-size: 0.9rem;
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.course-section {
    background: #fff;
    border: 1px solid #dce3ea;
    border-radius: 6px;
    padding: 1.25rem;
    box-shadow: 0 1px 3px rgba(20, 30, 40, 0.06);
}

.course-section h3 {
    margin: 0 0 0.35rem;
    color: #1f2d3a;
}

.course-section p {
    margin: 0 0 0.9rem;
    color: #586879;
}

.course-section ol {
    margin: 0;
    padding-left: 1.35rem;
}

.course-section li {
    margin-bottom: 0.35rem;
}

.course-section a,
.content a,
.breadcrumb a,
footer a {
    color: #1769aa;
}

.page-layout {
    display: grid;
    grid-template-columns: 250px minmax(0, 1fr);
    gap: 1.25rem;
    max-width: 1180px;
    align-items: start;
}

.site-nav {
    position: sticky;
    top: 1rem;
    max-height: calc(100vh - 2rem);
    overflow: auto;
    background: #fff;
    border: 1px solid #dce3ea;
    border-radius: 6px;
    padding: 1rem;
    box-shadow: 0 1px 3px rgba(20, 30, 40, 0.06);
}

.site-nav-home {
    display: block;
    font-weight: 700;
    color: #1f2d3a;
    text-decoration: none;
    margin-bottom: 1rem;
}

.site-nav section + section {
    margin-top: 1rem;
}

.site-nav h2 {
    font-size: 0.82rem;
    text-transform: uppercase;
    color: #607080;
    margin: 0 0 0.35rem;
}

.site-nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.site-nav li {
    margin: 0;
}

.site-nav a {
    display: block;
    color: #334456;
    text-decoration: none;
    border-radius: 4px;
    padding: 0.28rem 0.4rem;
    line-height: 1.35;
    font-size: 0.94rem;
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
    background-color: #edf4fb;
    color: #134f82;
}

.content {
    background-color: #fff;
    padding: 2.4rem 2.6rem;
    border-radius: 6px;
    box-shadow: 0 1px 3px rgba(20, 30, 40, 0.08);
}

.lesson-toc {
    background-color: #f7f9fb;
    border: 1px solid #dce3ea;
    border-radius: 6px;
    padding: 1rem;
    margin: 1rem 0 2rem;
}

.lesson-toc h4 {
    margin-top: 0;
    color: #253241;
}

.lesson-toc ul {
    columns: 2;
    margin: 0;
    padding-left: 1.25rem;
}

.lesson-toc li {
    break-inside: avoid;
    margin-bottom: 0.35rem;
}

/* Navigation breadcrumb */
.breadcrumb {
    padding: 1rem 0;
    font-size: 0.9rem;
}

.breadcrumb a {
    color: #007bff;
    text-decoration: none;
}

.breadcrumb a:hover {
    text-decoration: underline;
}

/* Content page navigation */
.page-nav {
    display: flex;
    justify-content: space-between;
    margin-top: 2rem;
    padding-top: 1rem;
    border-top: 1px solid #ddd;
}

.page-nav a {
    color: #007bff;
    text-decoration: none;
    padding: 0.5rem 1rem;
    border: 1px solid #007bff;
    border-radius: 4px;
    transition: all 0.3s ease;
}

.page-nav a:hover {
    background-color: #007bff;
    color: #fff;
}

.page-nav .prev::before {
    content: "← ";
}

.page-nav .next::after {
    content: " →";
}

/* Typography for content pages */
.content h3 {
    color: #1f2d3a;
    border-bottom: 1px solid #d8e0e8;
    padding-bottom: 0.65rem;
    margin-top: 2.25rem;
    margin-bottom: 1.25rem;
    font-size: 1.65rem;
    line-height: 1.25;
}

.content h3:first-child {
    margin-top: 0;
}

.content h4 {
    color: #253241;
    margin-top: 2rem;
    margin-bottom: 0.7rem;
    font-size: 1.18rem;
    line-height: 1.35;
}

.content h5 {
    color: #555;
    margin-top: 1rem;
    margin-bottom: 0.5rem;
}

.content p {
    margin-top: 0;
    margin-bottom: 1.05rem;
}

.content ul, .content ol {
    margin-left: 1.5rem;
    margin-bottom: 1rem;
}

.content ul li, .content ol li {
    margin-bottom: 0.5rem;
}

.content ul ul, .content ol ol {
    margin-top: 0.5rem;
}

/* Code blocks */
.content pre {
    background-color: #f8fafc;
    border: 1px solid #d8dee8;
    border-radius: 4px;
    padding: 1rem 1.1rem;
    overflow-x: auto;
    margin: 1rem 0 1.25rem;
    line-height: 1.55;
}

.content code {
    background-color: #f2f5f8;
    padding: 0.2rem 0.4rem;
    border-radius: 3px;
    font-family: 'Zenbones Brainy', 'Fira Code', 'Courier New', Courier, monospace;
    font-size: 0.9em;
}

.content pre code {
    background-color: transparent;
    padding: 0;
}

.content figure {
    margin: 1.5rem 0;
    padding: 1rem;
    border: 1px solid #dce3ea;
    border-radius: 6px;
    background-color: #fbfcfd;
}

.content figure p {
    margin: 0;
}

.content figure img {
    display: block;
    max-width: 100%;
    height: auto;
    margin: 0 auto;
}

.content figcaption {
    margin-top: 0.75rem;
    color: #607080;
    font-size: 0.92rem;
    text-align: center;
}

.content figcaption p {
    margin: 0;
}

.content .external-figure img {
    max-height: 360px;
    object-fit: contain;
}

.resource-card {
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    align-items: center;
    padding: 0.85rem 1rem;
    border: 1px solid #dce3ea;
    border-radius: 6px;
    background-color: #f7f9fb;
    color: #1f2d3a;
    text-decoration: none;
}

.resource-card:hover {
    background-color: #edf4fb;
    text-decoration: none;
}

.resource-card span {
    color: #607080;
    font-size: 0.9rem;
    white-space: nowrap;
}

.content .math {
    font-family: Georgia, 'Times New Roman', serif;
}

/* Tables */
.content table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 1rem;
}

.content table th,
.content table td {
    padding: 0.75rem;
    text-align: left;
    border-bottom: 1px solid #ddd;
}

.content table th {
    background-color: #f7f9fb;
    font-weight: bold;
    color: #253241;
}

.content table tr:hover {
    background-color: #f8f9fa;
}

/* Links in content */
.content a {
    color: #007bff;
    text-decoration: none;
}

.content a:hover {
    text-decoration: underline;
}

/* Endnotes/Footnotes */
.content section[role="doc-endnotes"] {
    margin-top: 2rem;
    padding-top: 1rem;
    border-top: 1px solid #ddd;
    font-size: 0.9rem;
}

.content section[role="doc-endnotes"] ol {
    list-style-type: none;
    padding-left: 0;
}

.content section[role="doc-endnotes"] li {
    margin-bottom: 0.5rem;
}

@media (max-width: 1024px) and (min-width: 769px) {
    .page-layout {
        grid-template-columns: 220px minmax(0, 1fr);
    }
}

@media (max-width: 768px) {
    header h1 {
        font-size: 1.5rem;
    }
    
    header p {
        font-size: 0.9rem;
    }
    
    .container {
        padding: 0.5rem;
    }

    .home-intro h2 {
        font-size: 1.45rem;
    }

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

    .site-nav {
        position: static;
        max-height: none;
    }
    
    .content {
        padding: 1.25rem;
    }
    
    .content h3 {
        font-size: 1.3rem;
    }
    
    .content h4 {
        font-size: 1.1rem;
    }
    
    .lesson-toc ul {
        columns: 1;
    }
    
    .page-nav {
        flex-direction: column;
        gap: 0.5rem;
    }
    
    .page-nav a {
        width: 100%;
        text-align: center;
    }
    
    .content pre {
        font-size: 0.85rem;
        padding: 0.75rem;
    }
    
    .content table {
        font-size: 0.9rem;
    }
    
    footer {
        font-size: 0.85rem;
        padding: 1rem 0.5rem;
    }
}

@media (max-width: 480px) {
    header h1 {
        font-size: 1.2rem;
    }
    
    .content h3 {
        font-size: 1.2rem;
    }
    
    .content {
        padding: 1rem;
    }
}