:root {
  --ground: #f7f8f5; --surface: #fff; --ink: #15191a; --muted: #5c6a64;
  --keo: #dc3a22; --line: #dde2da;
}
@media (prefers-color-scheme: dark) {
  :root {
    --ground: #101413; --surface: #171d1b; --ink: #eaeee9; --muted: #99a7a0;
    --keo: #ff6f52; --line: #2a322f;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0; background: var(--ground); color: var(--ink);
  font: 16px/1.65 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  -webkit-font-smoothing: antialiased;
}
.wrap { max-width: 640px; margin: 0 auto; padding: 56px 24px 96px; }
.mark { position: relative; display: inline-block; font-size: 44px; font-weight: 800;
  letter-spacing: -.04em; line-height: 1; padding-top: .18em; }
.mark i { position: absolute; left: .5em; top: 0; width: .27em; height: .085em;
  border-radius: .1em; background: var(--keo); transform: rotate(-22deg); }
h1 { font-size: 28px; line-height: 1.2; letter-spacing: -.02em; margin: 28px 0 10px; text-wrap: balance; }
h2 { font-size: 17px; margin: 30px 0 8px; }
p, li { color: var(--ink); }
.muted { color: var(--muted); }
code { background: var(--surface); border: 1px solid var(--line); border-radius: 5px;
  padding: .1em .4em; font-size: .9em; }
.code { display: block; font-size: 30px; font-weight: 800; letter-spacing: .18em;
  margin: 22px 0; font-family: ui-monospace, monospace; }
.btn { display: block; text-align: center; text-decoration: none; background: var(--keo);
  color: #fff; font-weight: 600; padding: 15px 20px; border-radius: 12px; margin: 10px 0; }
.btn.ghost { background: transparent; color: var(--ink); border: 1px solid var(--line); }
.note { background: var(--surface); border: 1px solid var(--line); border-left: 3px solid var(--keo);
  border-radius: 0 10px 10px 0; padding: 16px 18px; margin: 26px 0; font-size: 14.5px; }
footer { margin-top: 48px; padding-top: 20px; border-top: 1px solid var(--line);
  font-size: 13px; color: var(--muted); }
a { color: var(--keo); }

/* ---- bilingual pages ------------------------------------------------------ */
/* Bilingual without duplicating a page: both languages live in the markup and
   a body class decides which is visible. Vietnamese is the default, so the
   page is correct for the launch market even if the script never runs. */
/* `revert` rather than a fixed value: the same pair of classes has to work on
   a <span> inside a sentence and on a <p> or <ul> that is a block. */
.en { display: none; }
body.lang-en .vi { display: none; }
body.lang-en .en { display: revert; }

.langbar { display: flex; justify-content: flex-end; gap: 6px; padding-top: 20px; }
.langbar button {
  font: inherit; font-size: 13px; cursor: pointer; padding: 5px 12px;
  border-radius: 999px; border: 1px solid var(--line);
  background: transparent; color: var(--muted);
}
.langbar button[aria-pressed="true"] { background: var(--keo); border-color: var(--keo); color: #fff; }

.hero { padding: 30px 0 8px; }
.hero h1 { font-size: clamp(30px, 6vw, 42px); line-height: 1.15; letter-spacing: -.02em;
  margin: 26px 0 12px; text-wrap: balance; }
.hero .lede { font-size: 18px; color: var(--muted); margin: 0 0 26px; }

.steps { counter-reset: s; margin: 8px 0 8px; padding: 0; list-style: none; }
.steps li { counter-increment: s; display: grid; grid-template-columns: 34px 1fr;
  gap: 14px; padding: 13px 0; border-bottom: 1px solid var(--line); align-items: baseline; }
.steps li:last-child { border-bottom: 0; }
.steps li::before { content: counter(s, decimal-leading-zero);
  font-family: ui-monospace, monospace; font-size: 12px; font-weight: 700; color: var(--keo); }
.steps b { display: block; font-size: 16px; }
.steps b span, .feat b span { color: var(--ink); font-size: inherit; }
.steps span { color: var(--muted); font-size: 14.5px; }

.feat { display: grid; gap: 14px; margin: 6px 0 10px; padding: 0; list-style: none; }
.feat li { background: var(--surface); border: 1px solid var(--line);
  border-radius: 14px; padding: 16px 18px; }
.feat b { display: block; margin-bottom: 4px; }
.feat span { color: var(--muted); font-size: 14.5px; }

.soon { opacity: .55; pointer-events: none; }