/* =========================================================
   Chuhai — static site stylesheet
   No frameworks, no external fonts, no JS required.
   ========================================================= */

:root {
  --paper: #fbfaf7;
  --ink: #16191e;
  --muted: #5c6068;
  --line: #e3ded4;
  --line-strong: #cfc8ba;
  --accent: #9a3b2c;
  --accent-soft: #f3e4df;
  --dark: #14181f;
  --dark-2: #1d232c;
  --max: 1180px;
  --pad: clamp(20px, 5vw, 48px);
  --sans: ui-sans-serif, -apple-system, "Segoe UI", Roboto, "Helvetica Neue",
          Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
}

*,
*::before,
*::after { box-sizing: border-box; }

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.62;
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; display: block; }

a { color: inherit; text-decoration: none; }

a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.skip {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--ink);
  color: #fff;
  padding: 12px 18px;
  z-index: 999;
}
.skip:focus { left: 12px; top: 12px; }

/* --------------------------------------------------------- type */

h1, h2, h3, h4 {
  margin: 0;
  font-weight: 600;
  letter-spacing: -0.022em;
  line-height: 1.12;
}

h1 { font-size: clamp(2.15rem, 5.2vw, 3.9rem); }
h2 { font-size: clamp(1.65rem, 3.4vw, 2.55rem); }
h3 { font-size: clamp(1.12rem, 1.7vw, 1.32rem); letter-spacing: -0.01em; }

p { margin: 0 0 1.05em; }
p:last-child { margin-bottom: 0; }

.lede {
  font-size: clamp(1.05rem, 1.6vw, 1.24rem);
  line-height: 1.58;
  color: var(--muted);
  max-width: 62ch;
}

.eyebrow {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 18px;
}

.muted { color: var(--muted); }
.small { font-size: 0.88rem; }

/* --------------------------------------------------------- layout */

.wrap {
  width: 100%;
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 var(--pad);
}

section { padding: clamp(56px, 8vw, 104px) 0; }

.rule { height: 1px; background: var(--line); border: 0; margin: 0; }

.stack > * + * { margin-top: 20px; }

/* --------------------------------------------------------- header */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(251, 250, 247, 0.94);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}

.site-header .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 68px;
}

.brand {
  display: flex;
  align-items: baseline;
  gap: 10px;
  font-weight: 700;
  letter-spacing: 0.09em;
  font-size: 0.95rem;
}

.brand span {
  font-weight: 500;
  letter-spacing: 0.14em;
  font-size: 0.62rem;
  color: var(--muted);
  text-transform: uppercase;
}

.nav {
  display: flex;
  gap: 26px;
  overflow-x: auto;
  scrollbar-width: none;
  font-size: 0.92rem;
}
.nav::-webkit-scrollbar { display: none; }

.nav a {
  white-space: nowrap;
  color: var(--muted);
  padding: 6px 0;
  border-bottom: 1px solid transparent;
  transition: color 0.15s, border-color 0.15s;
}
.nav a:hover { color: var(--ink); }
.nav a[aria-current="page"] {
  color: var(--ink);
  border-bottom-color: var(--accent);
}

/* --------------------------------------------------------- buttons */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 24px;
  border: 1px solid var(--ink);
  background: var(--ink);
  color: #fff;
  font-size: 0.94rem;
  font-weight: 500;
  border-radius: 2px;
  transition: transform 0.15s, background 0.15s, color 0.15s;
}
.btn:hover { background: #000; transform: translateY(-1px); }

.btn--ghost {
  background: transparent;
  color: var(--ink);
  border-color: var(--line-strong);
}
.btn--ghost:hover { background: #fff; border-color: var(--ink); }

.btn--light {
  background: #fff;
  color: var(--ink);
  border-color: #fff;
}
.btn--light:hover { background: var(--accent-soft); border-color: var(--accent-soft); }

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 34px;
}

/* --------------------------------------------------------- hero */

.hero { padding: clamp(64px, 9vw, 128px) 0 clamp(48px, 6vw, 76px); }

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(0, 0.65fr);
  gap: clamp(32px, 5vw, 72px);
  align-items: end;
}

.hero h1 { max-width: 17ch; }

.hero-aside {
  border-left: 1px solid var(--line-strong);
  padding-left: 26px;
  font-size: 0.92rem;
  color: var(--muted);
}
.hero-aside strong {
  display: block;
  color: var(--ink);
  font-size: 0.78rem;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  margin-bottom: 10px;
}

/* --------------------------------------------------------- stats */

.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.stat {
  padding: 30px 26px;
  border-right: 1px solid var(--line);
}
.stat:last-child { border-right: 0; }

.stat b {
  display: block;
  font-size: clamp(1.55rem, 2.9vw, 2.2rem);
  font-weight: 600;
  letter-spacing: -0.03em;
  line-height: 1;
  margin-bottom: 10px;
}

.stat span {
  font-size: 0.78rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--muted);
}

/* --------------------------------------------------------- cards */

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.card {
  background: var(--paper);
  padding: clamp(26px, 3.4vw, 40px);
}

.card .num {
  font-size: 0.74rem;
  letter-spacing: 0.14em;
  color: var(--accent);
  font-weight: 600;
  display: block;
  margin-bottom: 16px;
}

.card h3 { margin-bottom: 12px; }
.card p { color: var(--muted); font-size: 0.96rem; }

/* --------------------------------------------------------- dark band */

.band-dark {
  background: var(--dark);
  color: #f2efe8;
}
.band-dark .eyebrow { color: #d98873; }
.band-dark .lede { color: #a8adb6; }

.band-dark .split {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: clamp(32px, 5vw, 72px);
  align-items: start;
}

.proof {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid #2c333d;
}
.proof li {
  padding: 22px 0;
  border-bottom: 1px solid #2c333d;
}
.proof b { display: block; margin-bottom: 6px; font-weight: 600; }
.proof span { color: #a8adb6; font-size: 0.95rem; }

/* --------------------------------------------------------- process */

.steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  margin-top: 44px;
}

.step {
  background: var(--paper);
  padding: 30px 26px 34px;
}

.step .idx {
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  color: var(--accent);
  font-weight: 600;
}

.step h3 {
  font-size: 1.05rem;
  margin: 14px 0 8px;
}

.step p {
  font-size: 0.92rem;
  color: var(--muted);
  margin: 0;
}

/* --------------------------------------------------------- tables */

.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--line);
  margin-top: 30px;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
  min-width: 560px;
}

th, td {
  text-align: left;
  padding: 14px 18px;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}

thead th {
  background: #fff;
  font-weight: 600;
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  border-bottom: 1px solid var(--line-strong);
}

tbody tr:last-child td { border-bottom: 0; }
tbody tr:hover { background: #fff; }

td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }

/* --------------------------------------------------------- color card */

.swatches {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  margin-top: 30px;
}

.swatch {
  background: var(--paper);
  padding: 14px 14px 16px;
}
.swatch i {
  display: block;
  height: 62px;
  margin-bottom: 12px;
  border: 1px solid rgba(0, 0, 0, 0.06);
}
.swatch b { display: block; font-size: 0.8rem; font-weight: 600; }
.swatch span {
  display: block;
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

/* --------------------------------------------------------- checklist */

.checklist {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  border-top: 1px solid var(--line);
}
.checklist li {
  padding: 15px 0 15px 30px;
  border-bottom: 1px solid var(--line);
  position: relative;
  font-size: 0.96rem;
}
.checklist li::before {
  content: "";
  position: absolute;
  left: 2px;
  top: 22px;
  width: 9px;
  height: 9px;
  border: 1px solid var(--accent);
  border-radius: 50%;
}

/* --------------------------------------------------------- cta */

.cta {
  background: var(--accent);
  color: #fff;
  padding: clamp(52px, 7vw, 84px) 0;
}
.cta h2 { max-width: 22ch; }
.cta p { color: #f0d5cd; max-width: 56ch; margin-top: 16px; }
.cta .btn {
  background: #fff;
  color: var(--ink);
  border-color: #fff;
  margin-top: 30px;
}
.cta .btn:hover { background: #f7ece9; }

/* --------------------------------------------------------- footer */

.site-footer {
  background: var(--dark);
  color: #99a0aa;
  padding: 56px 0 40px;
  font-size: 0.9rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr;
  gap: 40px;
}

.site-footer .brand { color: #fff; }
.site-footer h4 {
  color: #fff;
  font-size: 0.74rem;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  margin-bottom: 14px;
}
.site-footer a { color: #c6cbd3; }
.site-footer a:hover { color: #fff; }
.site-footer ul { list-style: none; margin: 0; padding: 0; }
.site-footer li + li { margin-top: 9px; }

.footer-base {
  margin-top: 44px;
  padding-top: 22px;
  border-top: 1px solid #2c333d;
  display: flex;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
  font-size: 0.8rem;
  color: #78808b;
}

/* --------------------------------------------------------- misc */

.page-head {
  padding: clamp(56px, 7vw, 96px) 0 clamp(34px, 4vw, 52px);
  border-bottom: 1px solid var(--line);
}
.page-head h1 { max-width: 20ch; }

.two-col {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: clamp(32px, 5vw, 72px);
  align-items: start;
}

.note {
  border-left: 3px solid var(--accent);
  background: var(--accent-soft);
  padding: 20px 24px;
  font-size: 0.94rem;
}
.note.dark {
  background: rgba(154, 59, 44, 0.16);
  border-left-color: #d98873;
  color: #e6e2da;
}

@media (max-width: 900px) {
  .hero-grid,
  .band-dark .split,
  .two-col { grid-template-columns: 1fr; }
  .hero-aside { border-left: 0; padding-left: 0; border-top: 1px solid var(--line); padding-top: 20px; }
  .stats { grid-template-columns: repeat(2, 1fr); }
  .stat:nth-child(2) { border-right: 0; }
  .stat:nth-child(1),
  .stat:nth-child(2) { border-bottom: 1px solid var(--line); }
  .grid-3 { grid-template-columns: 1fr; }
  .steps { grid-template-columns: repeat(2, 1fr); }
  .swatches { grid-template-columns: repeat(4, 1fr); }
  .footer-grid { grid-template-columns: 1fr; gap: 32px; }
}

@media (max-width: 560px) {
  body { font-size: 16px; }
  .steps { grid-template-columns: 1fr; }
  .swatches { grid-template-columns: repeat(2, 1fr); }
  .site-header .wrap { min-height: 60px; gap: 14px; }
  .brand span { display: none; }
}