/* Bridge the site's violet post accents with a quieter blue-indigo. */
body {
    --primary-color: #4f46e5;
    --primary-dark: #3730a3;
}

/* Blog Index */
.post-category-filter {
    display: flex;
    flex-wrap: wrap;
    gap: 0.65rem;
    margin: 1rem 0 2.25rem;
}

.post-category-button {
    border: 1px solid var(--border-color);
    border-radius: 999px;
    padding: 0.5rem 0.9rem;
    background: var(--bg-primary);
    color: var(--text-secondary);
    font: inherit;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

.post-category-button:hover,
.post-category-button.active {
    border-color: var(--primary-color);
    background: var(--primary-color);
    color: #fff;
}

.post-category-button:focus-visible {
    outline: 3px solid color-mix(in srgb, var(--primary-color) 25%, transparent);
    outline-offset: 2px;
}

.post-category-empty {
    padding: 2.5rem 0;
    color: var(--text-secondary);
}

.af-post-category,
.post-category {
    display: inline-block;
    color: var(--text-light);
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    line-height: 1.3;
    text-transform: uppercase;
}

.af-post-category {
    margin-bottom: 0.35rem;
}

.post-category {
    margin-bottom: 0.8rem;
    text-decoration: none;
}

.blog-main {
    min-height: 100vh;
    padding-top: 4rem;
    background-color: var(--bg-secondary);
}

.blog-header {
    padding: 4rem 0 2rem;
    text-align: center;
}

.blog-subtitle {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-top: -2rem;
    margin-bottom: 3rem;
}

.posts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 2rem;
    padding-bottom: 4rem;
}

.post-card {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 2rem;
    text-decoration: none;
    color: inherit;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.post-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.3s ease;
}

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

.post-card:hover::before {
    transform: scaleX(1);
}

.post-card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    flex-wrap: wrap;
}

.post-tags {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.post-tag {
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    font-size: 0.75rem;
    font-weight: 600;
    padding: 0.2rem 0.6rem;
    border-radius: 1rem;
    border: 1px solid var(--border-color);
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

.post-date {
    color: var(--text-light);
    font-size: 0.85rem;
    white-space: nowrap;
}

.post-title {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1.4;
}

.post-description {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
    flex: 1;
}

.post-read-more {
    color: var(--primary-color);
    font-size: 0.9rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 0.4rem;
    margin-top: 0.5rem;
}

.no-posts {
    color: var(--text-secondary);
    text-align: center;
    grid-column: 1 / -1;
    padding: 3rem;
}

/* Blog Post Page */
.post-page {
    min-height: 100vh;
    padding-top: 4rem;
    background-color: var(--bg-secondary);
}

.post-page-inner {
    max-width: 1120px;
    margin: 0 auto;
    padding: 3rem 2rem 5rem;
}

.post-reading-progress {
    position: fixed;
    inset: 0 auto auto 0;
    z-index: 1100;
    width: 0;
    height: 3px;
    background: linear-gradient(90deg, #4f46e5, #7c3aed);
    transition: width 80ms linear;
}

.post-layout {
    display: grid;
    grid-template-columns: 210px minmax(0, 760px);
    gap: 3rem;
    align-items: start;
}

.post-article {
    min-width: 0;
}

.post-toc {
    position: sticky;
    top: 6rem;
    max-height: calc(100vh - 8rem);
    overflow-x: hidden;
    overflow-y: auto;
}

.post-toc-inner {
    border-left: 1px solid var(--border-color);
    padding-left: 1rem;
}

.post-toc-title {
    margin-bottom: 0.65rem;
    color: var(--text-primary);
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.post-toc a {
    display: block;
    padding: 0.25rem 0;
    color: var(--text-light);
    font-size: 0.78rem;
    line-height: 1.35;
    overflow-wrap: anywhere;
    text-decoration: none;
    transition: color 160ms ease, transform 160ms ease;
}

.post-toc a[data-level="3"] {
    padding-left: 0.75rem;
    font-size: 0.74rem;
}

.post-toc a:hover,
.post-toc a.active {
    color: var(--primary-color);
}

.post-toc a.active {
    font-weight: 600;
    transform: translateX(3px);
}

.post-back {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    margin-bottom: 2.5rem;
    transition: var(--transition);
}

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

.post-meta {
    margin-bottom: 2.5rem;
}

.post-meta .post-tags {
    margin-bottom: 0.75rem;
}

.post-meta .post-date {
    font-size: 0.9rem;
    color: var(--text-light);
}

.post-meta h1 {
    font-size: 2.25rem;
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1.3;
    margin: 0.75rem 0;
}

.post-divider {
    border: none;
    border-top: 2px solid var(--border-color);
    margin: 2rem 0;
}

/* Markdown content styles */
.post-content {
    font-size: 1.05rem;
    line-height: 1.8;
    color: var(--text-primary);
}

.post-content h2 {
    font-size: 1.6rem;
    font-weight: 700;
    margin: 2.5rem 0 1rem;
    color: var(--text-primary);
    padding-bottom: 0.4rem;
    border-bottom: 2px solid var(--border-color);
}

.post-content h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin: 2rem 0 0.75rem;
    color: var(--text-primary);
}

.post-content h4 {
    font-size: 1.05rem;
    font-weight: 600;
    margin: 1.5rem 0 0.5rem;
    color: var(--text-primary);
}

.post-content p {
    margin-bottom: 1.25rem;
}

.post-content a {
    color: var(--primary-color);
    text-decoration: underline;
    text-underline-offset: 3px;
}

.post-content strong {
    font-weight: 700;
    color: var(--text-primary);
}

.post-content em {
    font-style: italic;
}

.post-content ul,
.post-content ol {
    padding-left: 1.75rem;
    margin-bottom: 1.25rem;
}

.post-content li {
    margin-bottom: 0.4rem;
}

.post-content blockquote {
    border-left: 4px solid var(--primary-color);
    padding: 0.75rem 1.25rem;
    margin: 1.5rem 0;
    background: var(--bg-tertiary);
    border-radius: 0 var(--border-radius) var(--border-radius) 0;
    color: var(--text-secondary);
    font-style: italic;
}

.post-content code {
    font-family: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;
    font-size: 0.88em;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    padding: 0.15em 0.4em;
    border-radius: 4px;
    color: var(--text-primary);
}

.post-content pre {
    background: #1e293b;
    border-radius: var(--border-radius);
    padding: 1.5rem;
    overflow-x: auto;
    margin: 1.5rem 0;
}

.post-content pre code {
    background: none;
    border: none;
    padding: 0;
    color: #e2e8f0;
    font-size: 0.9rem;
}

.post-content img {
    max-width: 100%;
    border-radius: var(--border-radius);
    margin: 1.5rem 0;
    box-shadow: var(--shadow-md);
}

.post-content table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
    font-size: 0.95rem;
}

.post-content th {
    background: var(--bg-tertiary);
    font-weight: 600;
    text-align: left;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
}

.post-content td {
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
}

.post-content tr:nth-child(even) td {
    background: var(--bg-secondary);
}

/* Interactive concept playgrounds */
.interactive-demo {
    margin: 2rem 0;
    border: 1px solid #dddaf7;
    border-radius: 14px;
    background: linear-gradient(145deg, #ffffff, #faf9ff);
    box-shadow: 0 14px 35px rgb(79 70 229 / 0.08);
    overflow: hidden;
}

.interactive-demo-header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 1rem;
    padding: 1rem 1.15rem 0.8rem;
}

.interactive-demo-kicker {
    margin-bottom: 0.2rem;
    color: var(--primary-color);
    font-size: 0.68rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.interactive-demo-title {
    color: var(--text-primary);
    font-size: 1rem;
    font-weight: 700;
}

.interactive-demo-copy {
    margin-top: 0.25rem;
    color: var(--text-secondary);
    font-size: 0.78rem;
    line-height: 1.45;
}

.interactive-demo-stage {
    position: relative;
    padding: 0 1rem 0.8rem;
}

.interactive-demo canvas {
    width: 100%;
    height: auto;
    display: block;
    border: 1px solid #ebe9f7;
    border-radius: 10px;
    background: #fff;
    touch-action: none;
}

.interactive-demo-controls {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 0.7rem 1rem;
    padding: 0.85rem 1.15rem 1.1rem;
    border-top: 1px solid #ebe9f7;
    background: rgb(248 247 255 / 0.75);
}

.interactive-control {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.75rem;
    font-weight: 600;
}

.interactive-control input[type="range"] {
    width: 120px;
    accent-color: var(--primary-color);
}

.interactive-control select,
.interactive-demo button {
    border: 1px solid #d9d6ef;
    border-radius: 7px;
    background: #fff;
    color: var(--text-primary);
    font: inherit;
}

.interactive-control select {
    padding: 0.35rem 0.5rem;
}

.interactive-demo button {
    padding: 0.42rem 0.7rem;
    cursor: pointer;
    font-size: 0.75rem;
    font-weight: 700;
    transition: border-color 160ms ease, color 160ms ease, transform 160ms ease;
}

.interactive-demo button:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    transform: translateY(-1px);
}

.interactive-metric {
    margin-left: auto;
    color: var(--text-secondary);
    font-size: 0.72rem;
    font-variant-numeric: tabular-nums;
}

/* KaTeX display math centering */
.post-content .katex-display {
    overflow-x: auto;
    overflow-y: hidden;
    padding: 0.5rem 0;
    margin: 1.5rem 0;
}

.math-error {
    color: #ef4444;
    font-family: monospace;
    font-size: 0.85em;
}

/* Loading / error states */
.post-loading,
.post-error {
    text-align: center;
    padding: 4rem 2rem;
    color: var(--text-secondary);
}

.post-error {
    color: #ef4444;
}

@media (max-width: 768px) {
    .posts-grid {
        grid-template-columns: 1fr;
    }

    .post-page-inner {
        padding: 2rem 1rem 4rem;
    }

    .post-layout {
        display: block;
    }

    .post-toc {
        position: static;
        max-height: none;
        margin-bottom: 2rem;
    }

    .post-toc-inner {
        padding: 0.85rem 1rem;
        border: 1px solid var(--border-color);
        border-radius: 10px;
        background: #fff;
    }

    .post-toc nav {
        display: grid;
        grid-template-columns: repeat(2, minmax(0, 1fr));
        gap: 0 0.8rem;
    }

    .post-toc a[data-level="3"] {
        display: none;
    }

    .post-meta h1 {
        font-size: 1.75rem;
    }

    .post-content {
        font-size: 1rem;
    }

    .interactive-demo-controls {
        align-items: flex-start;
    }

    .interactive-control {
        width: 100%;
        justify-content: space-between;
    }

    .interactive-control input[type="range"] {
        flex: 1;
    }

    .interactive-metric {
        width: 100%;
        margin-left: 0;
    }
}