:root {
  --bg: #f5f7fa; --surface: #ffffff; --ink: #121c26; --muted: #556270; --line: #dbe2ea;
  --accent: #0b6e7a; --accent-2: #e8590c; --accent-soft: #e2f2f4; --on-accent: #ffffff;
  --code-bg: #0f1922; --code-fg: #d8e3ec; --code-dim: #7d92a4;
  --warn: #8a5a00; --warn-soft: #fcf1da; --bar-old: #a3b0bd; --bar-new: #0b6e7a;
  --font: "Be Vietnam Pro", "Segoe UI", system-ui, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, Menlo, Consolas, monospace;
  --radius: 12px; --top: 60px;
}
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) {
  --bg: #0b1218; --surface: #121c25; --ink: #e5ecf2; --muted: #95a4b2; --line: #24333f;
  --accent: #4fc4ce; --accent-2: #ff8a4c; --accent-soft: #10303a; --on-accent: #06141a;
  --code-bg: #071016; --code-fg: #d8e3ec; --code-dim: #6f8699;
  --warn: #e7b553; --warn-soft: #33270c; --bar-old: #4a5a68; --bar-new: #4fc4ce; color-scheme: dark } }
:root[data-theme="dark"] {
  --bg: #0b1218; --surface: #121c25; --ink: #e5ecf2; --muted: #95a4b2; --line: #24333f;
  --accent: #4fc4ce; --accent-2: #ff8a4c; --accent-soft: #10303a; --on-accent: #06141a;
  --code-bg: #071016; --code-fg: #d8e3ec; --code-dim: #6f8699;
  --warn: #e7b553; --warn-soft: #33270c; --bar-old: #4a5a68; --bar-new: #4fc4ce; color-scheme: dark }

* { box-sizing: border-box }
[hidden] { display: none !important }
html { scroll-padding-top: calc(var(--top) + 16px); scroll-behavior: smooth }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto } }
body { margin: 0; background: var(--bg); color: var(--ink); font: 400 16px/1.65 var(--font); -webkit-text-size-adjust: 100% }
html[data-lang="en"] .vi, html[data-lang="vi"] .en { display: none !important }
a { color: var(--accent) }
a:focus-visible, button:focus-visible, summary:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px }
code { font-family: var(--mono); font-size: .88em; background: var(--accent-soft); padding: .1em .35em; border-radius: 5px; overflow-wrap: anywhere }
h1, h2, h3, h4 { line-height: 1.2; text-wrap: balance; margin: 0 }
.skip { position: absolute; left: -999px } .skip:focus { left: 16px; top: 8px; z-index: 99; background: var(--surface); padding: 8px 12px }

/* top bar */
.topbar { position: sticky; top: 0; z-index: 50; height: var(--top); display: flex; align-items: center; gap: 16px;
  padding: 0 clamp(16px, 3vw, 32px); background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(10px); border-bottom: 1px solid var(--line) }
.brand { font-weight: 800; font-size: 1.15rem; color: var(--ink); text-decoration: none; display: flex; align-items: center; gap: 2px }
.logo { background: var(--accent); color: var(--on-accent); border-radius: 7px; padding: 1px 6px; margin-right: 3px; font-size: .95rem }
.top-links { display: flex; gap: 20px; margin-left: 16px }
.top-links a { color: var(--muted); text-decoration: none; font-weight: 500; font-size: .95rem }
.top-links a:hover { color: var(--ink) }
.top-actions { margin-left: auto; display: flex; gap: 8px; align-items: center }
.lang-switch { display: flex; border: 1px solid var(--line); border-radius: 999px; padding: 3px; background: var(--surface) }
.lang-switch button { border: 0; background: none; color: var(--muted); font: 600 .82rem var(--font); padding: 5px 11px; border-radius: 999px; cursor: pointer; min-height: 32px }
.lang-switch button[aria-pressed="true"] { background: var(--accent); color: var(--on-accent) }
.icon-btn { display: inline-grid; place-items: center; border: 1px solid var(--line); background: var(--surface); color: var(--ink); width: 38px; height: 38px; border-radius: 10px; cursor: pointer; font-size: 1rem }
#menu-btn { display: none }

/* hero */
.hero { padding: clamp(48px, 8vw, 96px) clamp(16px, 4vw, 32px) clamp(40px, 6vw, 72px);
  background: radial-gradient(1200px 400px at 85% -10%, var(--accent-soft), transparent 70%), var(--bg); border-bottom: 1px solid var(--line) }
.hero-inner { max-width: 1080px; margin: 0 auto }
.badge { display: inline-block; font: 600 .78rem var(--mono); color: var(--accent); border: 1px solid var(--line); background: var(--surface); padding: 5px 12px; border-radius: 999px }
.hero h1 { font-size: clamp(2.1rem, 1.3rem + 3.6vw, 3.9rem); font-weight: 800; letter-spacing: -.02em; margin: 20px 0 16px; max-width: 18ch }
.hero h1 em { font-style: normal; color: var(--accent-2) }
.hero p { font-size: clamp(1.02rem, .95rem + .3vw, 1.18rem); color: var(--muted); max-width: 66ch; margin: 0 }
.hero-cta { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 28px }
.btn { display: inline-flex; align-items: center; min-height: 44px; padding: 0 20px; border-radius: 10px; font-weight: 600; text-decoration: none;
  border: 1px solid var(--line); background: var(--surface); color: var(--ink) }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--on-accent) }
.btn.ghost { background: transparent }
.btn:hover { filter: brightness(1.06) }
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1px; margin-top: 44px; background: var(--line); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden }
.stats div { background: var(--surface); padding: 18px 20px; color: var(--muted); font-size: .9rem; line-height: 1.4 }
.stats b { display: block; font-size: 1.9rem; color: var(--ink); font-weight: 800; letter-spacing: -.02em; margin-bottom: 4px; font-variant-numeric: tabular-nums }

/* layout */
.layout { max-width: 1240px; margin: 0 auto; display: grid; grid-template-columns: 240px minmax(0, 1fr); gap: 48px; padding: 0 clamp(16px, 3vw, 32px) }
.toc { position: sticky; top: calc(var(--top) + 24px); align-self: start; max-height: calc(100vh - var(--top) - 48px); overflow: auto; padding: 32px 0 }
.toc-title { font-size: .75rem; text-transform: uppercase; letter-spacing: .08em; color: var(--muted); font-weight: 700; margin-bottom: 10px }
.toc ol { list-style: none; margin: 0; padding: 0 }
.toc ol ol { padding-left: 12px; border-left: 1px solid var(--line); margin: 2px 0 6px 6px }
.toc a { display: block; padding: 4px 8px; border-radius: 6px; color: var(--muted); text-decoration: none; font-size: .9rem }
.toc ol ol a { font-size: .84rem; padding: 2px 8px }
.toc a:hover { color: var(--ink); background: var(--surface) }
.toc a.active { color: var(--accent); background: var(--accent-soft); font-weight: 600 }
main { min-width: 0; padding: 8px 0 64px; max-width: 860px }

section { padding: 48px 0 8px; border-bottom: 1px solid var(--line) }
section:last-of-type { border-bottom: 0 }
section h2 { font-size: clamp(1.55rem, 1.2rem + 1.2vw, 2.1rem); font-weight: 800; letter-spacing: -.015em; margin-bottom: 16px }
section h3 { font-size: 1.2rem; font-weight: 700; margin: 36px 0 12px }
section h4 { font-size: 1rem; font-weight: 700; margin-bottom: 8px }
section p { margin: 0 0 14px }
ul, ol { padding-left: 1.3em } li { margin: 4px 0 }

.cards { display: grid; gap: 14px; margin: 18px 0 }
.cards.three { grid-template-columns: repeat(3, 1fr) } .cards.two { grid-template-columns: repeat(2, 1fr) }
.card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px 20px }
.card p { color: var(--muted); font-size: .94rem; margin: 0 }
.card ul, .card ol { margin: 0; font-size: .94rem; color: var(--muted) }

.note { border-left: 4px solid var(--accent); background: var(--accent-soft); padding: 12px 16px; border-radius: 0 10px 10px 0; margin: 18px 0 }
.note p { margin: 0; font-size: .95rem }
.note.warn { border-color: var(--warn); background: var(--warn-soft) }

/* tables */
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius); margin: 16px 0; background: var(--surface) }
table { border-collapse: collapse; width: 100%; font-size: .92rem }
th, td { text-align: left; padding: 10px 14px; border-bottom: 1px solid var(--line); vertical-align: top }
th { font-size: .78rem; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); background: var(--bg) }
tr:last-child td { border-bottom: 0 }
.opts td:first-child, .cmds td:first-child { white-space: nowrap }
td { font-variant-numeric: tabular-nums }

/* code */
.code { margin: 16px 0; border-radius: var(--radius); overflow: hidden; background: var(--code-bg); border: 1px solid var(--line) }
.code-head { display: flex; justify-content: space-between; align-items: center; padding: 6px 8px 6px 14px; font: 600 .75rem var(--mono); color: var(--code-dim); border-bottom: 1px solid #ffffff14 }
.copy { border: 1px solid #ffffff22; background: transparent; color: var(--code-fg); font: 600 .75rem var(--font); border-radius: 6px; padding: 4px 10px; cursor: pointer; min-height: 28px }
.copy:hover { background: #ffffff14 }
pre { margin: 0; padding: 14px 16px; overflow-x: auto; color: var(--code-fg); font: 400 .85rem/1.6 var(--mono); tab-size: 4 }
pre code { background: none; padding: 0; font-size: inherit; overflow-wrap: normal; color: inherit }
pre .c { color: var(--code-dim) }

/* tabs */
.tabs { display: flex; gap: 4px; flex-wrap: wrap; border-bottom: 1px solid var(--line); margin: 22px 0 18px }
.tabs button { border: 0; background: none; padding: 10px 14px; font: 600 .93rem var(--font); color: var(--muted); cursor: pointer; border-bottom: 2px solid transparent; margin-bottom: -1px; min-height: 44px }
.tabs button[aria-selected="true"] { color: var(--accent); border-bottom-color: var(--accent) }

/* API */
.api { border: 1px solid var(--line); background: var(--surface); border-radius: 10px; padding: 12px 16px; margin: 10px 0 }
.api .sig { display: block; background: none; padding: 0; font-weight: 600; color: var(--ink); font-size: .86rem; margin-bottom: 4px }
.api-desc { color: var(--muted); font-size: .93rem }
.api-desc code { font-size: .84em }

.steps li { margin: 8px 0 }

/* bars */
.legend { display: flex; gap: 8px; align-items: center; font-size: .88rem; color: var(--muted); margin: 8px 0 }
.sw { display: inline-block; width: 12px; height: 12px; border-radius: 3px; margin-left: 8px } .sw.old { background: var(--bar-old) } .sw.new { background: var(--bar-new) }
.bars { display: grid; gap: 14px; margin: 18px 0 24px }
.bar-row { display: grid; grid-template-columns: 150px 1fr; gap: 12px; align-items: center }
.bar-label { font-size: .88rem; font-weight: 600 }
.bar-track { display: grid; gap: 3px }
.bar { height: 22px; border-radius: 4px; position: relative; min-width: 3px }
.bar.old { background: var(--bar-old) } .bar.new { background: var(--bar-new) }
.bar span { position: absolute; left: calc(100% + 8px); top: 50%; transform: translateY(-50%); white-space: nowrap; font: 600 .78rem var(--mono); color: var(--muted) }
.bar.new span { color: var(--ink) }
.bar.new[style*="100.00%"] span { left: auto; right: 8px; color: var(--on-accent) }

details { border: 1px solid var(--line); border-radius: 10px; background: var(--surface); margin: 10px 0; padding: 0 16px }
summary { cursor: pointer; font-weight: 600; padding: 14px 0; min-height: 44px }
details p { color: var(--muted) }
footer { padding: 32px 0 0; color: var(--muted); font-size: .88rem }

@media (max-width: 1000px) {
  .layout { grid-template-columns: minmax(0, 1fr); gap: 0 }
  .toc { position: fixed; top: var(--top); left: 0; right: 0; bottom: 0; max-height: none; z-index: 40; background: var(--bg); padding: 20px 16px; display: none }
  .toc.open { display: block }
  #menu-btn { display: inline-grid }
  .top-links { display: none }
  .stats { grid-template-columns: repeat(2, 1fr) }
  .cards.three { grid-template-columns: repeat(2, 1fr) }
}
@media (max-width: 640px) {
  .cards.three, .cards.two { grid-template-columns: 1fr }
  .bar-row { grid-template-columns: 1fr; gap: 4px }
  .bar span { font-size: .72rem }
  .opts td:first-child, .cmds td:first-child { white-space: normal }
}
td:first-child > code { white-space: nowrap; overflow-wrap: normal }