/* =========================================================
   BFNC Tutorials — main stylesheet
   ========================================================= */
:root {
  --bfnc-accent: #2563eb;
  --bfnc-accent-hover: #1d4ed8;
  --bfnc-font-heading: "Inter", system-ui, -apple-system, sans-serif;
  --bfnc-font-body: "Inter", system-ui, -apple-system, sans-serif;
  --bfnc-font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;

  --bg: #ffffff;
  --bg-soft: #f7f8fa;
  --bg-elev: #ffffff;
  --fg: #0f172a;
  --fg-muted: #475569;
  --border: #e5e7eb;
  --border-soft: #eef0f3;
  --code-bg: #0b1020;
  --code-fg: #e6edf3;
  --shadow-sm: 0 1px 2px rgba(15,23,42,.05);
  --shadow: 0 4px 16px rgba(15,23,42,.06);
  --radius: 12px;
  --radius-sm: 8px;
  --container: 1200px;
}

[data-theme="dark"] {
  --bg: #0b1020;
  --bg-soft: #0f172a;
  --bg-elev: #131a2e;
  --fg: #e6edf3;
  --fg-muted: #94a3b8;
  --border: #1f2a44;
  --border-soft: #1a2238;
  --shadow-sm: 0 1px 2px rgba(0,0,0,.4);
  --shadow: 0 8px 28px rgba(0,0,0,.4);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--bfnc-font-body);
  color: var(--fg);
  background: var(--bg);
  font-size: 17px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
img, svg, video { max-width: 100%; height: auto; display: block; }
a { color: var(--bfnc-accent); text-decoration: none; }
a:hover { color: var(--bfnc-accent-hover); text-decoration: underline; }

h1, h2, h3, h4, h5, h6 {
  font-family: var(--bfnc-font-heading);
  color: var(--fg);
  line-height: 1.25;
  margin: 1.4em 0 .5em;
  letter-spacing: -0.01em;
}
h1 { font-size: clamp(1.9rem, 1.4rem + 2vw, 2.75rem); font-weight: 700; }
h2 { font-size: clamp(1.45rem, 1.2rem + 1vw, 1.85rem); font-weight: 700; }
h3 { font-size: 1.25rem; font-weight: 600; }
p { margin: 0 0 1em; }

.container { max-width: var(--container); margin: 0 auto; padding: 0 24px; }
.screen-reader-text {
  position: absolute !important; width: 1px; height: 1px; padding: 0;
  margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0;
}
.skip-link { position: absolute; left: -9999px; top: 0; background: var(--bfnc-accent); color: #fff; padding: 10px 16px; z-index: 999; }
.skip-link:focus { left: 16px; top: 16px; }

/* ---------- Header ---------- */
.site-header {
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  position: relative;
  z-index: 50;
}
.has-sticky-header .site-header { position: sticky; top: 0; backdrop-filter: saturate(180%) blur(8px); background: color-mix(in oklab, var(--bg) 85%, transparent); }
.site-header__inner {
  display: flex; align-items: center; justify-content: space-between; gap: 24px;
  min-height: 72px;
}
.site-branding .site-title { margin: 0; font-size: 1.35rem; font-weight: 700; letter-spacing: -.02em; }
.site-branding .site-title a { color: var(--fg); }
.site-description { margin: 0; font-size: .85rem; color: var(--fg-muted); }
.custom-logo { max-height: 44px; width: auto; }

.main-navigation ul { list-style: none; margin: 0; padding: 0; display: flex; gap: 28px; }
.main-navigation a { color: var(--fg); font-weight: 500; }
.main-navigation a:hover { color: var(--bfnc-accent); text-decoration: none; }
.main-navigation .current-menu-item > a { color: var(--bfnc-accent); }

.menu-toggle { display: none; background: none; border: 0; padding: 8px; cursor: pointer; }
.menu-toggle .bar { display: block; width: 22px; height: 2px; background: var(--fg); margin: 5px 0; transition: .2s; }

.header-actions { display: flex; align-items: center; gap: 8px; }
.header-actions button { background: transparent; border: 1px solid var(--border); color: var(--fg); width: 40px; height: 40px; border-radius: 999px; display: inline-flex; align-items: center; justify-content: center; cursor: pointer; }
.header-actions button:hover { border-color: var(--bfnc-accent); color: var(--bfnc-accent); }
.theme-toggle .icon-moon { display: none; }
[data-theme="dark"] .theme-toggle .icon-sun { display: none; }
[data-theme="dark"] .theme-toggle .icon-moon { display: block; }

.header-search { border-top: 1px solid var(--border); padding: 16px 0; background: var(--bg-soft); }

/* ---------- Search form ---------- */
.search-form { display: flex; gap: 8px; max-width: 640px; }
.search-form .search-field {
  flex: 1; padding: 12px 16px; border: 1px solid var(--border); background: var(--bg-elev);
  color: var(--fg); border-radius: var(--radius); font: inherit; outline: none;
}
.search-form .search-field:focus { border-color: var(--bfnc-accent); box-shadow: 0 0 0 4px color-mix(in oklab, var(--bfnc-accent) 18%, transparent); }
.search-form .search-submit {
  background: var(--bfnc-accent); color: #fff; border: 0; padding: 0 18px; border-radius: var(--radius);
  cursor: pointer; display: inline-flex; align-items: center; gap: 6px; font-weight: 600;
}

/* ---------- Layout ---------- */
.site-content-wrap { padding: 32px 0 64px; }
.with-sidebar { display: grid; grid-template-columns: minmax(0, 1fr) 320px; gap: 48px; }
.content-area--full { max-width: 100%; }
.content-area--narrow { max-width: 720px; margin: 0 auto; }

@media (max-width: 960px) {
  .with-sidebar { grid-template-columns: 1fr; }
  .menu-toggle { display: inline-flex; flex-direction: column; }
  .main-navigation #primary-menu { display: none; position: absolute; top: 100%; left: 0; right: 0; flex-direction: column; gap: 0; background: var(--bg); border-top: 1px solid var(--border); padding: 12px 24px; }
  .main-navigation #primary-menu li { padding: 10px 0; border-bottom: 1px solid var(--border-soft); }
  .main-navigation.toggled #primary-menu { display: flex; }
}

/* ---------- Hero ---------- */
.hero {
  background:
    radial-gradient(1200px 400px at 20% 0%, color-mix(in oklab, var(--bfnc-accent) 14%, transparent), transparent 70%),
    radial-gradient(800px 400px at 100% 0%, color-mix(in oklab, var(--bfnc-accent) 10%, transparent), transparent 60%),
    var(--bg);
  border-bottom: 1px solid var(--border);
}
.hero__inner { padding: 72px 24px 56px; text-align: center; }
.eyebrow { text-transform: uppercase; letter-spacing: .12em; font-size: .8rem; color: var(--bfnc-accent); font-weight: 600; margin: 0 0 12px; }
.hero__title { margin: 0 0 12px; font-size: clamp(2.2rem, 1.4rem + 3vw, 3.5rem); }
.hero__subtitle { color: var(--fg-muted); max-width: 680px; margin: 0 auto 28px; font-size: 1.1rem; }
.hero__search { max-width: 560px; margin: 0 auto; }
.hero__chips { list-style: none; padding: 0; margin: 24px 0 0; display: flex; flex-wrap: wrap; justify-content: center; gap: 8px; }
.hero__chips a { background: var(--bg-elev); border: 1px solid var(--border); padding: 6px 14px; border-radius: 999px; color: var(--fg); font-size: .9rem; }
.hero__chips a:hover { border-color: var(--bfnc-accent); color: var(--bfnc-accent); text-decoration: none; }

/* ---------- Sections ---------- */
.section { padding: 64px 24px; }
.section-head { display: flex; align-items: end; justify-content: space-between; margin-bottom: 28px; gap: 16px; }
.section-title { margin: 0; font-size: 1.6rem; }
.section-link { font-weight: 600; }

/* ---------- Card grids ---------- */
.post-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 28px; }
.post-grid--3, .featured-grid { grid-template-columns: repeat(3, 1fr); }
@media (max-width: 800px) { .post-grid, .post-grid--3, .featured-grid { grid-template-columns: 1fr; } }

.post-card { background: var(--bg-elev); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; transition: transform .2s, box-shadow .2s; display: flex; flex-direction: column; }
.post-card:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.post-card__media { display: block; aspect-ratio: 16/10; background: var(--bg-soft); overflow: hidden; }
.post-card__media img { width: 100%; height: 100%; object-fit: cover; transition: transform .4s; }
.post-card:hover .post-card__media img { transform: scale(1.04); }
.post-card__placeholder { display: block; width: 100%; height: 100%; background: linear-gradient(135deg, color-mix(in oklab, var(--bfnc-accent) 25%, transparent), transparent); }
.post-card__body { padding: 20px 22px 24px; display: flex; flex-direction: column; gap: 8px; }
.post-card__cat { font-size: .75rem; text-transform: uppercase; letter-spacing: .1em; font-weight: 700; color: var(--bfnc-accent); }
.post-card__title { font-size: 1.25rem; margin: 0; line-height: 1.35; }
.post-card__title a { color: var(--fg); }
.post-card__title a:hover { color: var(--bfnc-accent); text-decoration: none; }
.post-card__excerpt { color: var(--fg-muted); margin: 4px 0 8px; }
.post-card__meta { color: var(--fg-muted); font-size: .85rem; display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
.dot { opacity: .5; }

/* Featured cards */
.feat-card { background: var(--bg-elev); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
.feat-card__media { display: block; aspect-ratio: 16/9; background: var(--bg-soft); overflow: hidden; }
.feat-card__media img { width: 100%; height: 100%; object-fit: cover; }
.feat-card__body { padding: 20px 22px 24px; }
.feat-card__cat { font-size: .75rem; text-transform: uppercase; letter-spacing: .1em; font-weight: 700; color: var(--bfnc-accent); }
.feat-card__title { font-size: 1.3rem; margin: 6px 0 8px; }
.feat-card__title a { color: var(--fg); }
.feat-card__excerpt { color: var(--fg-muted); margin: 0; }

/* Categories grid */
.categories-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }
@media (max-width: 800px) { .categories-grid { grid-template-columns: repeat(2, 1fr); } }
.cat-card { background: var(--bg-elev); border: 1px solid var(--border); padding: 18px 20px; border-radius: var(--radius); display: flex; flex-direction: column; gap: 4px; transition: .2s; }
.cat-card:hover { border-color: var(--bfnc-accent); transform: translateY(-2px); text-decoration: none; }
.cat-card__name { color: var(--fg); font-weight: 600; font-size: 1.05rem; }
.cat-card__count { color: var(--fg-muted); font-size: .85rem; }

/* ---------- Single article ---------- */
.single-article .entry-cats a { font-size: .75rem; text-transform: uppercase; letter-spacing: .12em; font-weight: 700; color: var(--bfnc-accent); }
.single-article .entry-title { margin: 8px 0 16px; font-size: clamp(2rem, 1.4rem + 1.6vw, 2.75rem); }
.entry-meta { display: flex; gap: 10px; align-items: center; color: var(--fg-muted); font-size: .9rem; flex-wrap: wrap; }
.entry-meta img { border-radius: 999px; }
.entry-thumb { margin: 24px 0 32px; border-radius: var(--radius); overflow: hidden; border: 1px solid var(--border); }

.entry-content { font-size: 1.075rem; }
.entry-content h2 { margin-top: 2em; }
.entry-content h3 { margin-top: 1.6em; }
.entry-content blockquote {
  border-left: 4px solid var(--bfnc-accent);
  padding: 4px 0 4px 20px; margin: 24px 0;
  color: var(--fg-muted); font-style: italic;
}
.entry-content ul, .entry-content ol { padding-left: 1.4em; }
.entry-content img { border-radius: var(--radius); }
.entry-content code, .entry-content pre {
  font-family: var(--bfnc-font-mono); font-size: .95em;
}
.entry-content :not(pre) > code {
  background: var(--bg-soft); padding: 2px 6px; border-radius: 6px; border: 1px solid var(--border-soft);
}
.entry-content pre {
  background: var(--code-bg); color: var(--code-fg);
  padding: 18px 20px; border-radius: var(--radius); overflow: auto;
  border: 1px solid #1f2a44; line-height: 1.55; font-size: .9rem;
}
.entry-content pre code { background: transparent; padding: 0; border: 0; color: inherit; }
.entry-content table { width: 100%; border-collapse: collapse; margin: 20px 0; }
.entry-content th, .entry-content td { border: 1px solid var(--border); padding: 10px 12px; text-align: left; }

/* TOC */
.bfnc-toc {
  background: var(--bg-soft); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 18px 22px; margin: 0 0 28px;
}
.bfnc-toc .toc-title { margin: 0 0 8px; font-size: .85rem; text-transform: uppercase; letter-spacing: .12em; color: var(--fg-muted); }
.bfnc-toc ol { margin: 0; padding-left: 1.2em; }
.bfnc-toc .toc-h3 { padding-left: 1em; font-size: .95em; }
.bfnc-toc a { color: var(--fg); }
.bfnc-toc a:hover { color: var(--bfnc-accent); }

/* Share bar */
.share-bar { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; margin: 20px 0; padding: 12px 0; border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.share-bar__label { font-size: .85rem; font-weight: 600; color: var(--fg-muted); margin-right: 4px; }
.share-btn { font-size: .85rem; padding: 6px 12px; border-radius: 999px; border: 1px solid var(--border); color: var(--fg); }
.share-btn:hover { border-color: var(--bfnc-accent); color: var(--bfnc-accent); text-decoration: none; }

/* Author box */
.author-box { display: flex; gap: 18px; padding: 24px; background: var(--bg-soft); border: 1px solid var(--border); border-radius: var(--radius); margin: 36px 0; }
.author-box__avatar { border-radius: 999px; }
.author-box__eyebrow { font-size: .75rem; text-transform: uppercase; letter-spacing: .12em; color: var(--fg-muted); margin: 0; }
.author-box__name { margin: 4px 0 6px; font-size: 1.2rem; }
.author-box__name a { color: var(--fg); }
.author-box__bio { margin: 0; color: var(--fg-muted); }

/* Related */
.related-posts { margin-top: 48px; }
.related-posts__title { margin-bottom: 20px; }

/* Author hero */
.author-hero { display: flex; gap: 24px; align-items: center; padding: 28px; background: var(--bg-soft); border: 1px solid var(--border); border-radius: var(--radius); margin-bottom: 28px; }
.author-hero__avatar { border-radius: 999px; }
.author-hero__name { margin: 4px 0 8px; }
.author-hero__bio { color: var(--fg-muted); margin: 0 0 8px; max-width: 60ch; }
.author-hero__link { font-size: .9rem; }

/* Sidebar */
.widget-area { font-size: .95rem; }
.has-sticky-sidebar .sidebar-sticky { position: sticky; top: 96px; }
.widget { background: var(--bg-elev); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px 20px; margin-bottom: 20px; }
.widget-title { margin: 0 0 12px; font-size: 1rem; text-transform: uppercase; letter-spacing: .1em; color: var(--fg-muted); }
.widget ul { list-style: none; margin: 0; padding: 0; }
.widget ul li { padding: 6px 0; border-bottom: 1px solid var(--border-soft); }
.widget ul li:last-child { border-bottom: 0; }

/* Pagination */
.pagination, .nav-links { display: flex; justify-content: center; gap: 6px; margin: 40px 0; flex-wrap: wrap; }
.pagination .page-numbers, .nav-links a, .nav-links span {
  display: inline-flex; align-items: center; justify-content: center;
  min-width: 40px; height: 40px; padding: 0 12px; border-radius: var(--radius-sm);
  border: 1px solid var(--border); color: var(--fg); font-weight: 600;
}
.pagination .current { background: var(--bfnc-accent); color: #fff; border-color: var(--bfnc-accent); }
.pagination a:hover { border-color: var(--bfnc-accent); color: var(--bfnc-accent); text-decoration: none; }

/* Breadcrumbs */
.breadcrumbs { background: var(--bg-soft); border-bottom: 1px solid var(--border); font-size: .85rem; }
.breadcrumbs ol { list-style: none; margin: 0; padding: 12px 0; display: flex; gap: 8px; flex-wrap: wrap; color: var(--fg-muted); }
.breadcrumbs li + li::before { content: "/"; margin-right: 8px; opacity: .6; }
.breadcrumbs a { color: var(--fg-muted); }

/* Buttons */
.btn { display: inline-block; padding: 12px 22px; border-radius: var(--radius); font-weight: 600; cursor: pointer; border: 0; }
.btn--primary { background: var(--bfnc-accent); color: #fff; }
.btn--primary:hover { background: var(--bfnc-accent-hover); color: #fff; text-decoration: none; }

/* Forms */
.contact-form label { display: block; margin: 12px 0; font-weight: 500; color: var(--fg); }
.contact-form input, .contact-form textarea, .contact-form select {
  display: block; width: 100%; margin-top: 6px;
  padding: 12px 14px; border: 1px solid var(--border);
  background: var(--bg-elev); color: var(--fg); border-radius: var(--radius); font: inherit;
}
.contact-form input:focus, .contact-form textarea:focus { outline: none; border-color: var(--bfnc-accent); box-shadow: 0 0 0 4px color-mix(in oklab, var(--bfnc-accent) 18%, transparent); }
.contact-form .form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
@media (max-width: 600px) { .contact-form .form-row { grid-template-columns: 1fr; } }
.contact-form .hp-field { position: absolute; left: -9999px; }

.alert { padding: 14px 18px; border-radius: var(--radius); margin: 16px 0; }
.alert--success { background: #ecfdf5; color: #065f46; border: 1px solid #a7f3d0; }
.alert--error { background: #fef2f2; color: #991b1b; border: 1px solid #fecaca; }
[data-theme="dark"] .alert--success { background: #052e22; color: #a7f3d0; border-color: #064e3b; }
[data-theme="dark"] .alert--error { background: #2c0b0b; color: #fecaca; border-color: #7f1d1d; }

/* 404 */
.error-404-main { padding: 80px 24px; }
.error-404 { max-width: 640px; margin: 0 auto; text-align: center; }
.error-404__code { font-size: clamp(5rem, 6rem + 4vw, 9rem); font-weight: 800; line-height: 1; margin: 0; background: linear-gradient(135deg, var(--bfnc-accent), color-mix(in oklab, var(--bfnc-accent) 50%, #ec4899)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.error-404__title { margin: 12px 0 8px; }
.error-404__text { color: var(--fg-muted); }
.error-404__search { margin: 24px 0; }

/* Ads */
.bfnc-ad { padding: 14px 0; text-align: center; }
.bfnc-ad--header { background: var(--bg-soft); border-bottom: 1px solid var(--border); }
.bfnc-ad--footer { background: var(--bg-soft); border-top: 1px solid var(--border); }
.bfnc-ad--sidebar { padding: 0; margin-bottom: 20px; }
.bfnc-inline-ad { margin: 28px 0; padding: 14px; background: var(--bg-soft); border: 1px dashed var(--border); border-radius: var(--radius); text-align: center; }

/* Footer */
.site-footer { background: var(--bg-soft); border-top: 1px solid var(--border); margin-top: 48px; }
.footer-grid { display: grid; grid-template-columns: 1.5fr 1fr 1fr 1fr; gap: 32px; padding: 56px 24px 32px; }
@media (max-width: 800px) { .footer-grid { grid-template-columns: 1fr 1fr; } }
@media (max-width: 480px) { .footer-grid { grid-template-columns: 1fr; } }
.footer-brand { margin: 8px 0 6px; font-size: 1.25rem; }
.footer-tagline { color: var(--fg-muted); }
.social-menu { list-style: none; padding: 0; margin: 14px 0 0; display: flex; gap: 8px; }
.social-menu a { display: inline-flex; width: 38px; height: 38px; border-radius: 999px; border: 1px solid var(--border); align-items: center; justify-content: center; color: var(--fg); font-size: .85rem; }
.social-menu a:hover { border-color: var(--bfnc-accent); color: var(--bfnc-accent); text-decoration: none; }
.footer-col .widget { background: transparent; border: 0; padding: 0; }
.footer-bottom { border-top: 1px solid var(--border); }
.footer-bottom__inner { display: flex; align-items: center; justify-content: space-between; gap: 16px; padding: 18px 0; flex-wrap: wrap; }
.copyright { margin: 0; color: var(--fg-muted); font-size: .9rem; }
.footer-menu { list-style: none; padding: 0; margin: 0; display: flex; gap: 18px; flex-wrap: wrap; }
.footer-menu a { color: var(--fg-muted); font-size: .9rem; }
.footer-menu a:hover { color: var(--bfnc-accent); }

/* Back to top */
.back-to-top {
  position: fixed; right: 20px; bottom: 20px; width: 44px; height: 44px;
  border-radius: 999px; background: var(--bfnc-accent); color: #fff; border: 0;
  display: inline-flex; align-items: center; justify-content: center; cursor: pointer;
  box-shadow: var(--shadow); z-index: 90;
}
.back-to-top:hover { background: var(--bfnc-accent-hover); }

/* Comments */
.comments-area { margin-top: 48px; }
.comment-list { list-style: none; padding: 0; }
.comment-body { padding: 16px 0; border-bottom: 1px solid var(--border-soft); }

/* Print */
@media print {
  .site-header, .site-footer, .bfnc-ad, .share-bar, .related-posts, .back-to-top, .widget-area { display: none !important; }
  body { color: #000; background: #fff; }
}