/* Fixed reading progress under the site navbar */
.read-progress {
    position: fixed;
    left: 0;
    right: 0;
    top: 64px;
    height: 3px;
    z-index: 1001;
    background: rgba(0, 0, 0, 0.06);
    pointer-events: none;
}

.read-progress__fill {
    width: 0%;
    height: 100%;
    background: linear-gradient(90deg, #0071e3, #5ac8fa);
    transition: width 0.12s ease-out;
}

@media (min-width: 1024px) {
    .read-progress {
        top: 68px;
    }
}

/* Tutorial hub + article pages */
.tutorial-page {
    min-width: 0;
    min-height: 100vh;
}

.tutorial-main {
    max-width: 1180px;
    margin: 0 auto;
    padding: 96px 20px 80px;
}

/* --- Hub --- */
.tutorial-hub-hero {
    position: relative;
    padding: 36px 28px 40px;
    margin-bottom: 36px;
    border-radius: 20px;
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.95) 0%, rgba(245, 247, 250, 0.98) 48%, rgba(232, 240, 255, 0.55) 100%);
    border: 1px solid rgba(0, 0, 0, 0.06);
    box-shadow: 0 8px 32px rgba(0, 113, 227, 0.07);
}

.tutorial-hub-hero::before {
    content: "";
    position: absolute;
    left: 0;
    top: 0;
    right: 0;
    height: 4px;
    border-radius: 20px 20px 0 0;
    background: linear-gradient(90deg, #0071e3, #5ac8fa, #af52de);
}

.tutorial-hub-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 18px;
    margin-top: 28px;
}

@media (min-width: 900px) {
    .tutorial-hub-grid {
        grid-template-columns: repeat(3, minmax(0, 1fr));
        gap: 20px;
    }
}

.tutorial-card-link {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    padding: 22px 20px;
    min-height: 100%;
    border-radius: 16px;
    background: var(--bg-card-light);
    border: 1px solid rgba(0, 0, 0, 0.06);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.04);
    color: inherit;
    text-decoration: none;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.tutorial-card-link:hover {
    opacity: 1;
    transform: translateY(-3px);
    box-shadow: 0 12px 28px rgba(0, 0, 0, 0.08);
}

.tutorial-card-icon {
    width: 44px;
    height: 44px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
    margin-bottom: 14px;
    background: rgba(0, 113, 227, 0.1);
    color: var(--accent-blue);
}

.tutorial-card-link:nth-child(2) .tutorial-card-icon {
    background: rgba(88, 86, 214, 0.12);
    color: var(--accent-violet);
}

.tutorial-card-link:nth-child(3) .tutorial-card-icon {
    background: rgba(52, 199, 89, 0.15);
    color: #248a3d;
}

.tutorial-card-link:nth-child(4) .tutorial-card-icon {
    background: rgba(255, 149, 0, 0.15);
    color: #c93400;
}

.tutorial-card-link:nth-child(5) .tutorial-card-icon {
    background: rgba(175, 82, 222, 0.12);
    color: #8944ab;
}

.tutorial-card-link:nth-child(6) .tutorial-card-icon {
    background: rgba(90, 200, 250, 0.2);
    color: #0071a8;
}

.tutorial-card-title {
    font-size: 17px;
    font-weight: 600;
    letter-spacing: -0.01em;
    margin-bottom: 8px;
    line-height: 1.25;
}

.tutorial-card-desc {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.5;
    flex: 1;
}

.tutorial-card-meta {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 8px;
    margin-top: 14px;
    font-size: 12px;
    color: var(--text-secondary);
}

.tutorial-tag {
    display: inline-block;
    padding: 4px 10px;
    border-radius: 980px;
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.02em;
    text-transform: uppercase;
    background: rgba(0, 0, 0, 0.05);
    color: var(--text-secondary);
}

.tutorial-path-strip {
    margin: 40px 0 8px;
    padding: 24px 22px;
    border-radius: 16px;
    background: var(--bg-card-light);
    border: 1px solid var(--border-color);
}

.tutorial-path-strip h2 {
    font-size: 15px;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.tutorial-path-flow {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 8px 10px;
    font-size: 14px;
    color: var(--text-secondary);
}

.tutorial-path-flow a {
    color: var(--accent-blue);
    font-weight: 500;
}

.tutorial-path-flow .path-sep {
    color: var(--border-color);
    user-select: none;
}

.tutorial-hub-aside {
    margin-top: 28px;
    padding: 20px 22px;
    border-radius: 14px;
    background: rgba(0, 113, 227, 0.06);
    border: 1px solid rgba(0, 113, 227, 0.12);
    font-size: 14px;
    line-height: 1.55;
    color: var(--text-primary);
}

.tutorial-hub-aside a {
    color: var(--accent-blue);
    font-weight: 500;
}

/* Breadcrumb + article chrome */
.tutorial-breadcrumb {
    font-size: 13px;
    color: var(--text-secondary);
    margin-bottom: 20px;
}

.tutorial-breadcrumb a {
    color: var(--accent-blue);
}

.tutorial-breadcrumb span {
    margin: 0 8px;
    color: var(--border-color);
}

.tutorial-article-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 12px 18px;
    font-size: 13px;
    color: var(--text-secondary);
    margin-bottom: 10px;
}

.tutorial-pullquote {
    margin: 28px 0;
    padding: 18px 22px;
    border-left: 4px solid var(--accent-blue);
    background: rgba(0, 113, 227, 0.06);
    border-radius: 0 12px 12px 0;
    font-size: 16px;
    font-weight: 500;
    line-height: 1.55;
    color: var(--text-primary);
}

.tutorial-key-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 14px;
    margin: 22px 0;
}

.tutorial-key-item {
    padding: 18px 16px;
    border-radius: 14px;
    background: var(--bg-card-light);
    border: 1px solid rgba(0, 0, 0, 0.06);
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.03);
}

.tutorial-key-item h4 {
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.tutorial-key-item h4 i {
    color: var(--accent-blue);
    font-size: 15px;
}

.tutorial-key-item p {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.5;
    margin: 0;
}

.tutorial-series-nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    gap: 16px;
    margin-top: 48px;
    padding-top: 28px;
    border-top: 1px solid var(--border-color);
}

.tutorial-series-nav a {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 15px;
    font-weight: 500;
    color: var(--accent-blue);
}

.tutorial-series-nav a[aria-disabled="true"] {
    color: var(--text-secondary);
    pointer-events: none;
    opacity: 0.5;
}

.tutorial-series-nav .series-next {
    margin-left: auto;
}

/* Legacy: hero / toc / article (single long page + sub-articles) */
.tutorial-hero {
    margin-bottom: 40px;
    padding-bottom: 28px;
    border-bottom: 1px solid var(--border-color);
}

.tutorial-kicker {
    font-size: 13px;
    font-weight: 600;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    color: var(--text-secondary);
    margin-bottom: 10px;
}

.tutorial-title {
    font-size: 34px;
    font-weight: 600;
    letter-spacing: -0.02em;
    color: var(--text-primary);
    line-height: 1.15;
    margin-bottom: 12px;
}

.tutorial-lead {
    font-size: 17px;
    color: var(--text-secondary);
    line-height: 1.55;
    max-width: 720px;
}

.tutorial-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-top: 22px;
}

.tutorial-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 20px;
    border-radius: 980px;
    font-size: 15px;
    font-weight: 500;
    border: none;
    cursor: pointer;
    transition: opacity 0.2s ease, transform 0.2s ease;
}

.tutorial-btn:hover {
    opacity: 0.92;
}

.tutorial-btn--primary {
    background: var(--accent-blue);
    color: #fff;
}

.tutorial-btn--secondary {
    background: var(--btn-bg);
    color: var(--text-primary);
}

a.tutorial-btn {
    text-decoration: none;
}

.tutorial-shell {
    display: grid;
    grid-template-columns: minmax(0, 220px) minmax(0, 1fr);
    gap: 40px 48px;
    align-items: start;
}

.tutorial-toc {
    position: sticky;
    top: 88px;
    padding: 18px 16px;
    background: var(--bg-card-light);
    border-radius: 16px;
    border: 1px solid rgba(0, 0, 0, 0.06);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.04);
}

.tutorial-toc-title {
    font-size: 12px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text-secondary);
    margin-bottom: 12px;
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    gap: 10px;
}

.tutorial-progress-pct {
    font-size: 13px;
    font-weight: 600;
    letter-spacing: 0.02em;
    text-transform: none;
    color: var(--accent-blue);
    font-variant-numeric: tabular-nums;
}

.tutorial-toc ol {
    list-style: none;
    margin: 0;
    padding: 0;
}

.tutorial-toc li {
    margin-bottom: 6px;
}

.tutorial-toc a {
    display: block;
    padding: 6px 0;
    font-size: 13px;
    color: var(--text-primary);
    border-radius: 8px;
    line-height: 1.35;
}

.tutorial-toc a:hover {
    color: var(--accent-blue);
    opacity: 1;
}

.tutorial-toc a.is-active {
    color: var(--accent-blue);
    font-weight: 600;
    background: rgba(0, 113, 227, 0.1);
    padding-left: 10px;
    padding-right: 10px;
    margin-left: -10px;
    margin-right: -10px;
    border-radius: 8px;
}

.tutorial-article section {
    scroll-margin-top: 96px;
}

.tutorial-article h2 {
    font-size: 24px;
    font-weight: 600;
    letter-spacing: -0.015em;
    margin: 44px 0 16px;
    color: var(--text-primary);
}

.tutorial-article h2:first-child {
    margin-top: 0;
}

.tutorial-article h3 {
    font-size: 17px;
    font-weight: 600;
    margin: 28px 0 10px;
    color: var(--text-primary);
}

.tutorial-article p {
    font-size: 15px;
    line-height: 1.65;
    color: var(--text-primary);
    margin-bottom: 14px;
}

.tutorial-article ul,
.tutorial-article ol {
    margin: 0 0 16px;
    padding-left: 1.35em;
    font-size: 15px;
    line-height: 1.6;
    color: var(--text-primary);
}

.tutorial-article li {
    margin-bottom: 8px;
}

.tutorial-article strong {
    font-weight: 600;
}

.tutorial-callout {
    margin: 20px 0;
    padding: 16px 18px;
    border-radius: 12px;
    font-size: 14px;
    line-height: 1.55;
}

.tutorial-callout--info {
    background: rgba(0, 113, 227, 0.08);
    border: 1px solid rgba(0, 113, 227, 0.15);
    color: var(--text-primary);
}

.tutorial-callout--warn {
    background: rgba(191, 72, 0, 0.08);
    border: 1px solid rgba(191, 72, 0, 0.2);
    color: var(--text-primary);
}

.tutorial-callout i {
    margin-right: 8px;
    opacity: 0.85;
}

.tutorial-compare-wrap {
    margin: 20px 0;
    overflow-x: auto;
    border-radius: 14px;
    border: 1px solid var(--border-color);
    background: var(--bg-card-light);
}

.tutorial-compare {
    width: 100%;
    border-collapse: collapse;
    font-size: 14px;
    min-width: 520px;
}

.tutorial-compare th,
.tutorial-compare td {
    padding: 14px 16px;
    text-align: left;
    vertical-align: top;
    border-bottom: 1px solid var(--border-color);
}

.tutorial-compare th {
    font-weight: 600;
    background: rgba(0, 0, 0, 0.03);
    color: var(--text-primary);
}

.tutorial-compare td {
    color: var(--text-primary);
    line-height: 1.5;
}

.tutorial-compare tr:last-child td {
    border-bottom: none;
}

.tutorial-step-list {
    counter-reset: tutstep;
    list-style: none;
    padding-left: 0;
    margin: 16px 0 20px;
}

.tutorial-step-list li {
    position: relative;
    padding-left: 40px;
    margin-bottom: 18px;
    font-size: 15px;
    line-height: 1.55;
}

.tutorial-step-list li::before {
    counter-increment: tutstep;
    content: counter(tutstep);
    position: absolute;
    left: 0;
    top: 0;
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--text-primary);
    color: #fff;
    font-size: 13px;
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
}

.tutorial-check-list {
    list-style: none;
    padding: 0;
    margin: 16px 0;
}

.tutorial-check-list li {
    position: relative;
    padding: 12px 14px 12px 40px;
    margin-bottom: 8px;
    border-radius: 12px;
    background: rgba(0, 0, 0, 0.03);
    font-size: 14px;
    line-height: 1.5;
}

.tutorial-check-list li::before {
    content: "\f00c";
    font-family: "Font Awesome 6 Free";
    font-weight: 900;
    position: absolute;
    left: 14px;
    top: 50%;
    transform: translateY(-50%);
    color: #34c759;
    font-size: 14px;
}

@media (min-width: 1024px) {
    .tutorial-main {
        padding-top: 120px;
    }

    .tutorial-title {
        font-size: 40px;
    }
}

@media (max-width: 900px) {
    .tutorial-shell {
        grid-template-columns: 1fr;
    }

    .tutorial-toc {
        position: relative;
        top: auto;
    }
}

@media (max-width: 768px) {
    .tutorial-main {
        padding-top: 88px;
        padding-bottom: 60px;
    }

    .tutorial-title {
        font-size: 28px;
    }

    .tutorial-article h2 {
        font-size: 21px;
    }

    .tutorial-hub-hero {
        padding: 28px 18px 32px;
    }

    .tutorial-hub-grid {
        grid-template-columns: 1fr;
    }

    .tutorial-path-flow {
        flex-direction: column;
        align-items: flex-start;
    }

    .tutorial-path-flow .path-sep {
        display: none;
    }
}

/* Single-page long-read mode (comfortable typography) */
.tutorial-page--reader {
    background: linear-gradient(180deg, #f0f2f5 0%, var(--bg-page) 320px);
}

.tutorial-main--single {
    max-width: 1220px;
}

.tutorial-reader-hero {
    margin-bottom: 36px;
    padding: 32px 28px 36px;
    border-radius: 20px;
    background: rgba(255, 255, 255, 0.92);
    border: 1px solid rgba(0, 0, 0, 0.06);
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.04);
}

.tutorial-reader-hero .tutorial-kicker {
    color: var(--accent-blue);
    letter-spacing: 0.04em;
}

.tutorial-shell--single {
    gap: 36px 44px;
}

@media (min-width: 1024px) {
    .tutorial-shell--single {
        grid-template-columns: 240px minmax(0, 1fr);
    }

    .tutorial-main--single {
        padding-top: 118px;
    }
}

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

.tutorial-toc-list > li {
    margin-bottom: 4px;
}

.tutorial-toc-part {
    list-style: none;
    padding: 14px 0 6px;
    margin-top: 4px;
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--text-secondary);
    border-top: 1px solid rgba(0, 0, 0, 0.06);
}

.tutorial-toc-list > li.tutorial-toc-part:first-child {
    border-top: none;
    padding-top: 0;
}

.tutorial-article--prose {
    width: 100%;
    max-width: none;
    min-width: 0;
    padding-bottom: 48px;
}

.tutorial-article--prose p {
    font-size: 16px;
    line-height: 1.75;
    letter-spacing: 0.01em;
    color: #2d2d2f;
    margin-bottom: 16px;
}

.tutorial-article--prose h2 {
    font-size: 26px;
    font-weight: 600;
    letter-spacing: -0.02em;
    margin: 0 0 14px;
    line-height: 1.25;
    color: var(--text-primary);
}

.tutorial-article--prose h3 {
    font-size: 17px;
    margin-top: 22px;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.tutorial-article--prose ul,
.tutorial-article--prose ol {
    font-size: 16px;
    line-height: 1.7;
    margin-bottom: 18px;
}

.tutorial-article--prose li {
    margin-bottom: 10px;
}

.tutorial-chapter {
    margin-bottom: 28px;
    padding: 28px 26px 26px;
    border-radius: 18px;
    background: var(--bg-card-light);
    border: 1px solid rgba(0, 0, 0, 0.055);
    box-shadow: 0 2px 16px rgba(0, 0, 0, 0.03);
}

.tutorial-chapter + .tutorial-chapter {
    margin-top: 8px;
}

.tutorial-article--prose .tutorial-chapter h2 {
    padding-bottom: 12px;
    margin-bottom: 18px;
    border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}

.tutorial-article--prose .tutorial-pullquote {
    margin: 22px 0;
    font-size: 17px;
    line-height: 1.6;
}

.tutorial-article--prose .tutorial-key-grid {
    margin: 18px 0 8px;
}

.tutorial-article--prose .tutorial-callout {
    font-size: 15px;
    line-height: 1.6;
}

@media (max-width: 768px) {
    .tutorial-reader-hero {
        padding: 24px 18px 28px;
    }

    .tutorial-chapter {
        padding: 22px 18px 20px;
        border-radius: 16px;
    }

    .tutorial-article--prose h2 {
        font-size: 22px;
    }

    .tutorial-article--prose p,
    .tutorial-article--prose ul,
    .tutorial-article--prose ol {
        font-size: 15px;
    }
}

@media (prefers-reduced-motion: reduce) {
    .read-progress__fill {
        transition: none;
    }

    .tutorial-card-link {
        transition: none;
    }
}