:root {
  --bg: #f6f8fb; --panel: #ffffff; --panel2: #f1f4f9; --text: #162030; --muted: #5a6877; --line: #dde3ec;
  --brand: #1f5fbf; --brand2: #174a96; --brand-ink: #ffffff; --accent: #0f8a5f; --warn: #9a5b00; --warn-bg: #fff4de;
  --code-bg: #0f1b2d; --code-ink: #e6edf7; --shadow: 0 1px 2px rgba(16,24,40,.06), 0 4px 14px rgba(16,24,40,.06);
  --radius: 12px; --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #0e141b; --panel: #16202b; --panel2: #1b2733; --text: #e5ebf2; --muted: #98a7b8; --line: #283543;
    --brand: #5b9bff; --brand2: #8ab6ff; --brand-ink: #0b1220; --accent: #4fd39b; --warn: #f0b457; --warn-bg: #33270f;
    --code-bg: #0a1018; --code-ink: #dce6f2; --shadow: none; }
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 84px; }
body { margin: 0; background: var(--bg); color: var(--text); font: 16px/1.65 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; }
a { color: var(--brand); } a:hover { color: var(--brand2); }
.skip { position: absolute; left: -999px; top: 8px; background: var(--brand); color: var(--brand-ink); padding: 8px 12px; border-radius: 8px; z-index: 100; }
.skip:focus { left: 8px; }
.wrap { width: 100%; max-width: 1080px; margin: 0 auto; padding: 0 20px; }
h1 { font-size: clamp(28px, 4vw, 40px); line-height: 1.15; margin: 28px 0 10px; letter-spacing: -.01em; }
h2 { font-size: 24px; margin: 38px 0 12px; letter-spacing: -.005em; } h3 { font-size: 17px; margin: 0 0 6px; }
p { margin: 0 0 14px; } .lead { font-size: 18px; color: var(--muted); max-width: 760px; }
code { font-family: var(--mono); font-size: .88em; background: var(--panel2); border: 1px solid var(--line); padding: 1px 6px; border-radius: 6px; }
.eyebrow { color: var(--accent); font-weight: 650; letter-spacing: .06em; text-transform: uppercase; font-size: 13px; margin: 0 0 6px; }

/* header */
.top { position: sticky; top: 0; z-index: 20; background: color-mix(in srgb, var(--panel) 92%, transparent); backdrop-filter: blur(8px); border-bottom: 1px solid var(--line); }
.bar { display: flex; align-items: center; gap: 18px; min-height: 64px; flex-wrap: wrap; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 750; color: var(--text); text-decoration: none; font-size: 18px; }
.logo { width: 34px; height: 34px; border-radius: 9px; background: var(--brand); color: var(--brand-ink); display: grid; place-items: center; font-weight: 800; }
.menu { display: flex; gap: 4px; flex-wrap: wrap; margin-left: 10px; flex: 1; }
.menu a { color: var(--text); text-decoration: none; padding: 8px 12px; border-radius: 8px; font-weight: 550; font-size: 15px; }
.menu a:hover { background: var(--panel2); } .menu a.active { background: color-mix(in srgb, var(--brand) 14%, transparent); color: var(--brand); }
.btn { display: inline-block; font: inherit; font-weight: 650; padding: 10px 18px; border-radius: 10px; border: 1px solid var(--line); background: var(--panel); color: var(--text); text-decoration: none; cursor: pointer; }
.btn:hover { background: var(--panel2); color: var(--text); } .btn.primary { background: var(--brand); color: var(--brand-ink); border-color: transparent; } .btn.primary:hover { filter: brightness(1.08); color: var(--brand-ink); }
.signin { padding: 8px 18px; }
a:focus-visible, .btn:focus-visible { outline: 3px solid color-mix(in srgb, var(--brand) 55%, transparent); outline-offset: 2px; }

/* hero */
.hero { padding: 54px 0 24px; }
.hero h1 { font-size: clamp(32px, 5.2vw, 52px); max-width: 860px; margin-top: 0; }
.actions { display: flex; flex-wrap: wrap; gap: 10px; margin: 18px 0 6px; }

/* cards / grids */
.grid { display: grid; gap: 16px; } .g2 { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); } .g3 { grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); }
.card { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow); }
.card p:last-child, .card ul:last-child { margin-bottom: 0; }
.card.warn { background: var(--warn-bg); border-color: color-mix(in srgb, var(--warn) 35%, var(--line)); } .card.warn h3 { color: var(--warn); }
.two { display: grid; gap: 16px; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); margin-top: 38px; } .two h2 { margin-top: 0; font-size: 20px; }
.cta { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px; margin: 40px 0; } .cta h2 { margin: 0 0 4px; font-size: 20px; }
.more { font-weight: 650; text-decoration: none; }
.note { background: var(--panel2); border: 1px solid var(--line); border-radius: 10px; padding: 12px 16px; margin-top: 22px; }

/* lists */
.steps { counter-reset: s; list-style: none; padding: 0; margin: 14px 0; display: grid; gap: 12px; }
.steps > li { counter-increment: s; position: relative; background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 14px 16px 14px 58px; box-shadow: var(--shadow); }
.steps > li::before { content: counter(s); position: absolute; left: 16px; top: 13px; width: 28px; height: 28px; border-radius: 50%; background: var(--brand); color: var(--brand-ink); font-weight: 750; display: grid; place-items: center; }
.ticks { list-style: none; padding: 0; margin: 8px 0; } .ticks li { padding-left: 24px; position: relative; margin: 6px 0; }
.ticks li::before { content: ""; position: absolute; left: 3px; top: .62em; width: 8px; height: 8px; border-radius: 50%; background: var(--accent); }
.check { list-style: none; padding: 0; } .check li { padding: 6px 0 6px 30px; position: relative; border-bottom: 1px dashed var(--line); }
.check li::before { content: "✓"; position: absolute; left: 4px; color: var(--accent); font-weight: 800; }

/* code + tables */
.code { background: var(--code-bg); color: var(--code-ink); border-radius: 10px; padding: 14px 16px; overflow-x: auto; font: 13px/1.55 var(--mono); margin: 10px 0 16px; border: 1px solid color-mix(in srgb, var(--line) 50%, transparent); }
.code code { background: none; border: 0; padding: 0; color: inherit; font-size: inherit; }
.table-wrap { overflow-x: auto; margin: 10px 0 16px; border: 1px solid var(--line); border-radius: 10px; background: var(--panel); }
table { width: 100%; border-collapse: collapse; font-size: 15px; } th, td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--line); vertical-align: top; }
th { font-size: 12.5px; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); background: var(--panel2); } tr:last-child td { border-bottom: 0; }

/* toc */
.toc { display: flex; flex-wrap: wrap; gap: 8px; margin: 14px 0 6px; } .toc a { text-decoration: none; background: var(--panel); border: 1px solid var(--line); padding: 6px 12px; border-radius: 999px; font-size: 14px; font-weight: 600; }
.toc a:hover { background: var(--panel2); }

/* sequence diagram */
.seq { width: 100%; height: auto; background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 8px; margin: 8px 0 16px; }
.seq .sq-box rect { fill: var(--brand); } .seq .sq-title text { fill: var(--brand-ink); font: 650 15px system-ui, sans-serif; }
.seq .sq-line line { stroke: var(--line); stroke-width: 2; stroke-dasharray: 5 5; } .seq .sq-arrow line { stroke: var(--text); stroke-width: 1.8; } .seq .sq-head { fill: var(--text); }
.seq .sq-text text { fill: var(--text); font: 14px system-ui, sans-serif; } .seq .sq-text .sq-sub { fill: var(--muted); font-size: 12.5px; }
.seq .sq-note rect { fill: var(--panel2); stroke: var(--line); } .seq .sq-note text { fill: var(--muted); font: 13.5px system-ui, sans-serif; }

/* footer */
.foot { margin-top: 56px; border-top: 1px solid var(--line); background: var(--panel); } .foot-in { display: flex; flex-wrap: wrap; gap: 14px; justify-content: space-between; padding: 22px 20px; color: var(--muted); font-size: 14px; }
.foot-links { display: flex; flex-wrap: wrap; gap: 6px 16px; } .foot-links a { color: var(--muted); text-decoration: none; } .foot-links a:hover { color: var(--brand); text-decoration: underline; }
@media (max-width: 760px) {
  .bar { gap: 8px 12px; padding-top: 8px; padding-bottom: 8px; }
  .menu { order: 3; flex: 1 1 100%; margin: 0; gap: 6px; overflow-x: auto; flex-wrap: nowrap; padding-bottom: 6px; -webkit-overflow-scrolling: touch; }
  .menu a { white-space: nowrap; background: var(--panel2); border: 1px solid var(--line); padding: 6px 12px; }
  .menu a.active { border-color: transparent; }
  .signin { margin-left: auto; }
}
@media print { .top, .foot, .toc { display: none; } body { background: #fff; color: #000; } }

.center { text-align: center; } .center .lead { margin-left: auto; margin-right: auto; } .actions.center { justify-content: center; } .hero.center { padding: 90px 0 30px; }