:root {
  --bg: #ffffff;
  --surface: #ffffff;
  --ink: #101418;
  --muted: #5f6672;
  --faint: #9aa1ad;
  --border: #e7e9ee;
  --accent: #e8552d;
  --accent-soft: #fef2ee;
  --radius: 16px;
  --maxw: 1020px;
  --ease-out: cubic-bezier(0.23, 1, 0.32, 1); /* strong ease-out for UI motion */
  --sans: -apple-system, BlinkMacSystemFont, "Inter", "PingFang SC", "Microsoft YaHei",
    "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b0d10;
    --surface: #14171c;
    --ink: #f3f4f6;
    --muted: #9ca3af;
    --faint: #697180;
    --border: #23272f;
    --accent: #ff7a56;
    --accent-soft: #2a1a14;
  }
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }

/* ---------- top nav ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 10;
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--border);
}
.nav .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}
.brand { font-weight: 800; font-size: 16px; color: var(--ink); letter-spacing: -0.01em; white-space: nowrap; }
.brand .by { color: var(--faint); font-weight: 500; }
.brand .dot { color: var(--accent); }
.brand:hover { text-decoration: none; color: var(--accent); }
.nav-links { display: flex; gap: 26px; }
.nav-links a {
  color: var(--muted); font-size: 14px; font-weight: 500;
  position: relative; padding: 4px 0;
  white-space: nowrap;
}
.nav-links a::after {
  content: ""; position: absolute; left: 0; bottom: 0;
  width: 100%; height: 2px; background: var(--accent);
  border-radius: 2px; transform: scaleX(0); transform-origin: left;
  transition: transform .22s ease;
}
.nav-links a:hover { color: var(--ink); text-decoration: none; }

/* ---------- language toggle ---------- */
.nav-right { display: flex; align-items: center; gap: 22px; }
.lang-toggle {
  display: inline-flex;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 2px;
}
.lang-toggle button {
  font-family: var(--sans);
  font-size: 13px; font-weight: 600;
  line-height: 1;
  color: var(--muted);
  background: transparent;
  border: 0;
  border-radius: 999px;
  padding: 5px 11px;
  cursor: pointer;
  transition: color .15s ease, background .15s ease, transform 160ms var(--ease-out);
}
.lang-toggle button:hover { color: var(--ink); }
.lang-toggle button:active { transform: scale(0.97); }
.lang-toggle button.on { color: #fff; background: var(--accent); }
@media (max-width: 520px) { .nav-right { gap: 12px; } .nav-links { gap: 14px; } }
/* 窄屏放不下一行：标识单独一行，菜单和语言切换排到第二行 */
@media (max-width: 440px) {
  .nav .wrap { height: auto; flex-wrap: wrap; row-gap: 4px; padding-top: 10px; padding-bottom: 10px; }
  .nav-right { width: 100%; justify-content: space-between; }
}

/* ---------- hero ---------- */
.hero {
  padding: 104px 0 64px;
  background:
    radial-gradient(circle at 1px 1px, color-mix(in srgb, var(--ink) 9%, transparent) 1px, transparent 0);
  background-size: 26px 26px;
}
.hero h1 {
  font-size: clamp(34px, 6.4vw, 60px);
  line-height: 1.08;
  letter-spacing: -0.035em;
  margin: 0 0 20px;
  font-weight: 800;
}
.hero h1 .dot { color: var(--accent); }
.hero p {
  font-size: 18px;
  color: var(--muted);
  max-width: 620px;
  margin: 0;
}

/* ---------- section headings ---------- */
.section { padding: 44px 0 8px; }
.section-head {
  display: flex; align-items: baseline; justify-content: space-between;
  margin-bottom: 18px;
}
.section-head h2 {
  font-size: 22px; margin: 0; font-weight: 800; letter-spacing: -0.02em;
}
.section-head .count { color: var(--faint); font-weight: 500; font-size: 16px; }

/* ---------- filters ---------- */
.filters { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 24px; }
.chip {
  font-family: var(--sans);
  font-size: 13.5px; font-weight: 500;
  color: var(--muted);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 6px 15px;
  cursor: pointer;
  transition: color .15s ease, border-color .15s ease, background .15s ease, transform 160ms var(--ease-out);
}
.chip:active { transform: scale(0.97); }
.chip.on {
  color: #fff; background: var(--accent); border-color: var(--accent);
}

/* ---------- project cards（两列瀑布，列内排位可控）---------- */
.cards { display: flex; align-items: flex-start; gap: 20px; transition: opacity 160ms var(--ease-out); }
.cards.switching { opacity: 0; }
@media (prefers-reduced-motion: reduce) { .cards { transition: none; } }
.cards .col { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 20px; }
@media (max-width: 680px) { .cards { flex-direction: column; } .cards .col { width: 100%; } }

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px;
  transition: transform .18s var(--ease-out), border-color .18s ease, box-shadow .18s ease, opacity .18s var(--ease-out);
}
.card.hide { display: none; }
.card .kicker {
  display: inline-block;
  font-size: 11.5px; font-weight: 700;
  color: var(--accent);
  background: var(--accent-soft);
  border-radius: 999px;
  padding: 3px 10px;
  letter-spacing: .07em; text-transform: uppercase;
  margin-bottom: 12px;
}
.card h3 { margin: 0 0 8px; font-size: 19px; font-weight: 750; letter-spacing: -0.01em; }
.card h3 .ico { width: 30px; height: 30px; border-radius: 8px; vertical-align: -7px; margin-right: 10px; }
.card h3 .wm { height: 20px; width: auto; vertical-align: -3px; margin-right: 10px; }
.card h3 a { color: var(--ink); }
.card h3 a:hover { color: var(--accent); text-decoration: none; }
.card .desc { color: var(--muted); font-size: 14.5px; margin: 0 0 16px; }
.card .think {
  background: color-mix(in srgb, var(--border) 34%, transparent);
  border-left: 3px solid var(--accent);
  border-radius: 8px;
  padding: 13px 15px;
  font-size: 14px;
  color: var(--ink);
  margin: 0;
}
.card .think b { color: var(--accent); }
.card .links { margin-top: 16px; display: flex; gap: 16px; align-items: center; flex-wrap: wrap; }
.card .links a { font-size: 14px; font-weight: 600; }
.card .links a:hover { text-decoration: none; }
.card .links .arr { display: inline-block; transition: transform .18s var(--ease-out); }
.card .links a.store {
  color: #fff; background: var(--accent);
  padding: 6px 14px; border-radius: 999px;
  box-shadow: 0 8px 20px -12px color-mix(in srgb, var(--accent) 70%, transparent);
  transition: transform 160ms var(--ease-out), filter .15s ease;
}
.card .links a.store:active { transform: scale(0.97); }

/* ---------- about ---------- */
.about-body { color: var(--muted); max-width: 640px; }

/* ---------- hover 效果（仅在真正支持 hover 的设备上启用，避免触屏点按后卡在 hover 态）---------- */
@media (hover: hover) and (pointer: fine) {
  .nav-links a:hover::after { transform: scaleX(1); }
  /* 变色只作用于非激活标签，激活态（.on）保持橙底白字 */
  .chip:not(.on):hover {
    color: var(--ink);
    border-color: color-mix(in srgb, var(--ink) 25%, var(--border));
  }
  .chip:hover { transform: translateY(-1px); }
  .card:hover {
    transform: translateY(-3px);
    border-color: color-mix(in srgb, var(--accent) 45%, var(--border));
    box-shadow: 0 14px 36px -18px color-mix(in srgb, var(--accent) 30%, rgba(0,0,0,.25));
  }
  .card .links a:hover .arr { transform: translateX(4px); }
  .card .links a.store:hover { filter: brightness(1.05); }
}

/* ---------- 滚动浮现 ---------- */
.reveal { opacity: 0; transform: translateY(14px); transition: opacity .45s var(--ease-out), transform .45s var(--ease-out); }
.reveal.in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
}

/* ---------- footer ---------- */
.footer {
  border-top: 1px solid var(--border);
  margin-top: 88px; padding: 32px 0 56px;
  color: var(--faint); font-size: 13.5px;
  display: flex; justify-content: space-between; flex-wrap: wrap; gap: 12px;
}
.footer a { color: var(--muted); }