:root {
  --paper: #faf7f2;
  --paper-2: #f2ede4;
  --card: #ffffff;
  --ink: #1c1a17;
  --ink-2: #5b564e;
  --line: #e4ddd1;
  --accent: #e0562b;
  --accent-ink: #b8401a;
  --accent-soft: #fde8df;
  --teal: #1f6f6b;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(28, 26, 23, 0.04), 0 6px 20px rgba(28, 26, 23, 0.05);
  --font: 'Be Vietnam Pro', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --paper: #161513;
    --paper-2: #1e1c19;
    --card: #211f1b;
    --ink: #f1ece4;
    --ink-2: #aaa296;
    --line: #34302a;
    --accent: #f2744b;
    --accent-ink: #ff8d66;
    --accent-soft: #3a2219;
    --teal: #6cc1bb;
    --shadow: none;
    color-scheme: dark;
  }
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent-ink); text-underline-offset: 3px; }
a:hover { color: var(--accent); }
img { max-width: 100%; height: auto; border-radius: 10px; }
h1, h2, h3 { line-height: 1.25; letter-spacing: -0.015em; margin: 0 0 0.5em; }
h1 { font-size: clamp(2rem, 5vw, 3.1rem); font-weight: 800; }
h2 { font-size: clamp(1.35rem, 3vw, 1.7rem); font-weight: 700; }
h3 { font-size: 1.15rem; font-weight: 700; }
p { margin: 0 0 1em; }

.wrap { width: 100%; max-width: 1080px; margin: 0 auto; padding: 0 16px; }
.narrow { max-width: 740px; }
.section { padding: 28px 16px; }
.muted { color: var(--ink-2); }
.small { font-size: 0.85rem; }
.eyebrow { font-size: 0.78rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; color: var(--teal); margin: 0 0 0.4em; }
.eyebrow a { color: inherit; text-decoration: none; }
.lead { font-size: 1.15rem; color: var(--ink-2); max-width: 640px; }
.accent { color: var(--accent); }
.skip { position: absolute; left: -9999px; }
.skip:focus { left: 16px; top: 8px; background: var(--card); padding: 8px 12px; z-index: 10; }

/* header */
.site-header { position: sticky; top: 0; z-index: 5; background: color-mix(in srgb, var(--paper) 88%, transparent); backdrop-filter: blur(10px); border-bottom: 1px solid var(--line); }
.header-inner { display: flex; align-items: center; justify-content: space-between; gap: 12px; min-height: 60px; flex-wrap: wrap; }
.brand { display: inline-flex; align-items: center; gap: 10px; font-weight: 800; color: var(--ink); text-decoration: none; font-size: 1.05rem; }
.brand-mark { display: inline-grid; place-items: center; width: 30px; height: 30px; border-radius: 9px; background: var(--accent); color: #fff; font-weight: 800; font-size: 1rem; transform: rotate(-6deg); flex: none; }
.brand-mark.big { width: 48px; height: 48px; font-size: 1.5rem; border-radius: 13px; }
.site-header nav ul { display: flex; gap: 4px; list-style: none; margin: 0; padding: 0; flex-wrap: wrap; }
.site-header nav a { display: block; padding: 6px 10px; border-radius: 8px; color: var(--ink-2); text-decoration: none; font-weight: 500; font-size: 0.95rem; }
.site-header nav a:hover, .site-header nav a[aria-current] { color: var(--ink); background: var(--paper-2); }

/* hero */
.hero { padding: 64px 0 36px; }
.hero h1 { max-width: 920px; }
.catch-badge { display: inline-block; background: var(--accent-soft); color: var(--accent-ink); font-weight: 800; padding: 5px 12px; border-radius: 999px; font-size: 0.9rem; margin-bottom: 18px; }
.actions { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 24px; }
.btn { display: inline-flex; align-items: center; gap: 6px; padding: 11px 20px; border-radius: 11px; background: var(--accent); color: #fff; font-weight: 700; text-decoration: none; border: 1.5px solid var(--accent); font-size: 0.98rem; }
.btn:hover { background: var(--accent-ink); border-color: var(--accent-ink); color: #fff; }
.btn-ghost { background: transparent; color: var(--ink); border-color: var(--line); }
.btn-ghost:hover { background: var(--paper-2); color: var(--ink); border-color: var(--ink-2); }
span.btn-ghost { cursor: default; }

/* grids, cards */
.section-head { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; margin-bottom: 16px; }
.grid { display: grid; gap: 16px; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); }
.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow); }
.post-card h3 a { color: var(--ink); text-decoration: none; }
.post-card h3 a:hover { color: var(--accent); }
.post-card .muted { font-size: 0.95rem; }
.meta { font-size: 0.85rem; color: var(--ink-2); margin: 0; }
.grid.projects { grid-template-columns: repeat(auto-fill, minmax(230px, 1fr)); }
.project { display: flex; flex-direction: column; }
.project .muted { flex: 1; font-size: 0.95rem; }
.link-arrow { font-weight: 700; text-decoration: none; }
.soon { font-weight: 700; color: var(--ink-2); }
.cat-card { text-decoration: none; color: var(--ink); }
.cat-card:hover { border-color: var(--accent); }
.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip { display: inline-block; font-size: 0.78rem; font-weight: 700; padding: 3px 10px; border-radius: 999px; background: var(--paper-2); color: var(--teal); text-decoration: none; margin-bottom: 10px; border: 1px solid var(--line); }
.chip-lg { font-size: 0.95rem; padding: 7px 14px; }
.chip:hover { border-color: var(--teal); }
.empty { padding: 24px; border: 1px dashed var(--line); border-radius: var(--radius); }
.page-head { padding-top: 48px; }

/* post */
.post-head { padding-top: 40px; padding-bottom: 8px; }
.crumbs { font-size: 0.85rem; color: var(--ink-2); margin-bottom: 14px; }
.crumbs a { color: var(--ink-2); text-decoration: none; }
.crumbs a:hover { color: var(--accent); }
.post-head h1 { font-size: clamp(1.8rem, 4.4vw, 2.6rem); }
.toc { background: var(--paper-2); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px 20px; margin: 24px 0; }
.toc ol { margin: 0; padding-left: 20px; }
.toc li { margin: 4px 0; }
.toc a { color: var(--ink); text-decoration: none; }
.toc a:hover { color: var(--accent); }
.prose { font-size: 1.06rem; }
.prose h2 { margin-top: 1.8em; }
.prose h3 { margin-top: 1.4em; }
.prose .anchor { position: absolute; margin-left: -1.1em; opacity: 0; text-decoration: none; color: var(--ink-2); }
.prose h2:hover .anchor, .prose h3:hover .anchor { opacity: 1; }
.prose h2, .prose h3 { position: relative; scroll-margin-top: 80px; }
.prose ul, .prose ol { padding-left: 1.3em; }
.prose li { margin: 0.3em 0; }
.prose blockquote { margin: 1.4em 0; padding: 4px 20px; border-left: 4px solid var(--accent); background: var(--accent-soft); border-radius: 0 10px 10px 0; }
.prose blockquote p { margin: 0.6em 0; }
.prose code { background: var(--paper-2); padding: 2px 6px; border-radius: 6px; font-size: 0.9em; }
.prose pre { background: #1c1a17; color: #f1ece4; padding: 16px; border-radius: 12px; overflow-x: auto; }
.prose pre code { background: none; padding: 0; }
.prose hr { border: none; border-top: 1px solid var(--line); margin: 2em 0; }
.prose figure { margin: 1.5em 0; }
.prose figcaption { font-size: 0.85rem; color: var(--ink-2); text-align: center; margin-top: 6px; }
.table-wrap { overflow-x: auto; margin: 1.4em 0; }
.prose table { border-collapse: collapse; width: 100%; font-size: 0.95rem; }
.prose th, .prose td { border: 1px solid var(--line); padding: 8px 12px; text-align: left; vertical-align: top; }
.prose th { background: var(--paper-2); }

.video { margin: 20px 0; }
.yt-lite, .video iframe { position: relative; display: block; width: 100%; aspect-ratio: 16 / 9; border: 0; border-radius: var(--radius); background: #000 center / cover no-repeat; cursor: pointer; }
.yt-lite .play { position: absolute; inset: 0; margin: auto; width: 68px; height: 48px; display: grid; place-items: center; background: var(--accent); color: #fff; border-radius: 14px; font-size: 22px; }
.video-link { margin: 16px 0; }

.faq { margin-top: 2.2em; }
.faq details { border: 1px solid var(--line); border-radius: 12px; padding: 12px 16px; margin: 10px 0; background: var(--card); }
.faq summary { cursor: pointer; font-weight: 700; }
.faq details > div { margin-top: 8px; color: var(--ink-2); }
.tags { margin-top: 2em; }
.tag { font-size: 0.85rem; color: var(--ink-2); }
.author-box { display: flex; gap: 16px; align-items: flex-start; margin: 2.2em 0; padding: 20px; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.author-box p { margin: 0 0 0.3em; }
.cta-box { margin: 2em 0; padding: 26px; border-radius: var(--radius); background: var(--ink); color: var(--paper); }
.cta-box .eyebrow { color: var(--accent); }
.cta-box h2 { color: var(--paper); }
.cta-box p { color: color-mix(in srgb, var(--paper) 80%, transparent); }
.cta-box .btn-ghost { color: var(--paper); border-color: color-mix(in srgb, var(--paper) 35%, transparent); }

/* footer */
.site-footer { margin-top: 48px; border-top: 1px solid var(--line); padding: 32px 0 16px; background: var(--paper-2); }
.footer-inner { display: flex; justify-content: space-between; gap: 24px; flex-wrap: wrap; }
.footer-brand { font-weight: 800; display: flex; align-items: center; gap: 10px; }
.catch { font-weight: 800; color: var(--accent); }
.footer-links { display: flex; flex-wrap: wrap; gap: 8px 18px; align-content: flex-start; max-width: 460px; }
.footer-links a { color: var(--ink-2); text-decoration: none; font-size: 0.95rem; }
.footer-links a:hover { color: var(--accent); }

@media (max-width: 560px) {
  body { font-size: 16px; }
  .hero { padding-top: 36px; }
  .header-inner { padding-top: 8px; padding-bottom: 8px; }
  .site-header nav a { padding: 5px 8px; font-size: 0.9rem; }
  .author-box { flex-direction: column; }
}

.todo { background: #ffe066; color: #1c1a17; padding: 1px 6px; border-radius: 5px; font-weight: 700; }

/* logo */
.logo-mark{height:30px;width:auto;display:block}
.logo-mark.big{height:44px;flex:none}
.logo-full{height:auto;display:block;border-radius:0}
.footer-brand .logo-full{width:220px;max-width:100%}
.hero-grid{display:grid;grid-template-columns:1.25fr 1fr;gap:32px;align-items:center}
.hero-logo{width:100%;max-width:440px;justify-self:center}
@media (max-width:760px){.hero-grid{grid-template-columns:1fr}.hero-logo{max-width:260px;justify-self:start;order:-1}}
@media (prefers-color-scheme:dark){
  .logo-mark,.logo-full{background:#fff;border-radius:10px;padding:4px 6px}
  .hero-logo,.footer-brand .logo-full{padding:14px 18px;border-radius:16px}
}

/* Ebook tặng đổi email */
.ebook-box { display: grid; grid-template-columns: 180px 1fr; gap: 24px; align-items: start; margin: 2.2em 0; padding: 22px; border: 2px solid var(--accent); border-radius: 16px; background: var(--accent-soft); }
.ebook-cover { width: 180px; height: auto; border-radius: 8px; box-shadow: 0 8px 22px rgba(0,0,0,.18); }
.ebook-body h2 { margin: 2px 0 8px; font-size: 1.35rem; }
.ebook-body > p { margin: 0 0 14px; }
.ebook-form { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.ebook-form input[type=text], .ebook-form input[type=email] { padding: 11px 13px; border: 1.5px solid var(--line); border-radius: 10px; font: inherit; background: var(--card); color: var(--ink); min-width: 0; }
.ebook-form input:focus { outline: 2px solid var(--accent); border-color: var(--accent); }
.ebook-form .consent { grid-column: 1 / -1; display: flex; gap: 8px; align-items: flex-start; font-size: .88rem; color: var(--ink-2); }
.ebook-form .consent input { margin-top: 3px; accent-color: var(--accent); }
.ebook-form .btn { grid-column: 1 / -1; justify-content: center; cursor: pointer; }
.ebook-form .btn[disabled] { opacity: .6; cursor: wait; }
.ebook-form .hp { position: absolute; left: -9999px; width: 1px; height: 1px; opacity: 0; }
.form-msg { grid-column: 1 / -1; margin: 0; font-size: .92rem; min-height: 1.2em; }
.form-msg.err { color: #c0392b; }
.form-ok { grid-column: 1 / -1; margin: 0; padding: 12px 14px; background: var(--card); border-radius: 10px; }
@media (max-width: 640px) {
  .ebook-box { grid-template-columns: 1fr; padding: 18px; }
  .ebook-cover { width: 140px; }
  .ebook-form { grid-template-columns: 1fr; }
}