/* ==========================================================================
   base.css — 浅色编辑风 / Light editorial
   Shared tokens, reset, header, footer, buttons, typography helpers.
   ========================================================================== */

:root {
  --paper: #ffffff;
  --paper-2: #faf9f6;
  --paper-3: #f2f0ea;
  --ink: #0b0b0c;
  --ink-2: #2e3136;
  --muted: #6b6f76;
  --faint: #9a9d9f;
  --line: #dedbd3;
  --line-2: #eceae4;
  --red: #e5401f;
  --red-ink: #b92f13;
  --green: #1c6b45;
  --amber: #a9740f;
  --max: 1320px;
  --gutter: 48px;
  --head-h: 64px;
  --mono: "SFMono-Regular", ui-monospace, "Cascadia Mono", "JetBrains Mono", Consolas, monospace;
  --sans: "Helvetica Neue", Helvetica, Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --serif: "Songti SC", "STSong", "SimSun", Georgia, serif;
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--head-h) + 24px);
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink-2);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.72;
  padding-top: var(--head-h);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

::selection {
  background: var(--red);
  color: #fff;
}

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

a {
  color: inherit;
}

button {
  font: inherit;
  color: inherit;
}

h1,
h2,
h3,
h4,
p,
ul,
ol,
dl,
dd,
figure,
blockquote {
  margin: 0;
}

ul,
ol {
  padding: 0;
}

:focus-visible {
  outline: 2px solid var(--red);
  outline-offset: 3px;
}

.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 100;
  padding: 10px 16px;
  background: var(--ink);
  color: #fff;
  font-size: 13px;
  text-decoration: none;
  transform: translateY(-160%);
  transition: transform 0.2s ease;
}

.skip-link:focus {
  transform: none;
}

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

/* --------------------------------------------------------------------------
   Header
   -------------------------------------------------------------------------- */

.site-head {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 60;
  height: var(--head-h);
  background: rgba(255, 255, 255, 0.94);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line);
  transition: box-shadow 0.25s ease;
}

.site-head.is-scrolled {
  box-shadow: 0 1px 0 rgba(11, 11, 12, 0.04);
}

.site-head__in {
  height: 100%;
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 var(--gutter);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: var(--ink);
  text-decoration: none;
  flex: 0 0 auto;
}

.brand__mark {
  width: 30px;
  height: 30px;
  background: var(--ink);
  color: #fff;
  display: grid;
  place-items: center;
  font-family: var(--mono);
  font-size: 15px;
  line-height: 1;
  transition: background 0.2s ease;
}

.brand:hover .brand__mark {
  background: var(--red);
}

.brand__text {
  display: flex;
  flex-direction: column;
  line-height: 1.15;
}

.brand__text strong {
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.02em;
}

.brand__text em {
  font-family: var(--mono);
  font-size: 9.5px;
  letter-spacing: 0.16em;
  color: var(--muted);
  font-style: normal;
  margin-top: 3px;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 30px;
}

.site-nav a {
  position: relative;
  padding: 6px 0;
  color: var(--ink-2);
  font-size: 14px;
  text-decoration: none;
  white-space: nowrap;
}

.site-nav a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 100%;
  bottom: 0;
  height: 1px;
  background: var(--ink);
  transition: right 0.25s ease;
}

.site-nav a:hover::after,
.site-nav a.is-active::after {
  right: 0;
}

.site-nav a.is-active {
  color: var(--ink);
  font-weight: 600;
}

.site-head__actions {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 0 0 auto;
}

.nav-toggle {
  display: none;
  height: 38px;
  padding: 0 14px;
  border: 1px solid var(--line);
  background: transparent;
  color: var(--ink);
  font-size: 12.5px;
  cursor: pointer;
}

/* --------------------------------------------------------------------------
   Buttons & links
   -------------------------------------------------------------------------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  height: 48px;
  padding: 0 24px;
  border: 1px solid var(--ink);
  background: var(--ink);
  color: #fff;
  font-size: 13.5px;
  letter-spacing: 0.01em;
  text-decoration: none;
  cursor: pointer;
  transition: background 0.2s ease, border-color 0.2s ease, color 0.2s ease;
}

.btn:hover {
  background: var(--red);
  border-color: var(--red);
  color: #fff;
}

.btn--ghost {
  background: transparent;
  color: var(--ink);
}

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

.btn--sm {
  height: 38px;
  padding: 0 16px;
  font-size: 12.5px;
}

.btn__arrow {
  font-family: var(--mono);
  font-size: 14px;
  line-height: 1;
}

.link-arrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding-bottom: 3px;
  border-bottom: 1px solid var(--ink);
  color: var(--ink);
  font-size: 14px;
  text-decoration: none;
  transition: color 0.2s ease, border-color 0.2s ease, gap 0.2s ease;
}

.link-arrow:hover {
  color: var(--red);
  border-color: var(--red);
  gap: 12px;
}

/* --------------------------------------------------------------------------
   Section furniture
   -------------------------------------------------------------------------- */

.section {
  padding: 104px 0;
}

.kicker {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 22px;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

.kicker::before {
  content: "";
  width: 26px;
  height: 1px;
  background: var(--red);
  flex: 0 0 auto;
}

.mono {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */

.site-foot {
  border-top: 1px solid var(--ink);
  padding: 40px 0 48px;
}

.site-foot__in {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 40px;
  flex-wrap: wrap;
}

.foot-brand {
  display: flex;
  flex-direction: column;
  gap: 6px;
  color: var(--ink);
  font-size: 14px;
  font-weight: 600;
}

.foot-brand em {
  font-family: var(--mono);
  font-size: 10px;
  font-weight: 400;
  font-style: normal;
  letter-spacing: 0.16em;
  color: var(--muted);
}

.foot-nav {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
}

.foot-nav a {
  color: var(--ink-2);
  font-size: 13px;
  text-decoration: none;
}

.foot-nav a:hover {
  color: var(--red);
}

.foot-meta {
  text-align: right;
  font-family: var(--mono);
  font-size: 10.5px;
  line-height: 1.9;
  letter-spacing: 0.08em;
  color: var(--muted);
}

/* --------------------------------------------------------------------------
   Reveal (subtle, motion-safe)
   -------------------------------------------------------------------------- */

.js .reveal {
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

.js .reveal.is-in {
  opacity: 1;
  transform: none;
}

.js.still .reveal {
  opacity: 1;
  transform: none;
  transition: none;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .js .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
}

/* --------------------------------------------------------------------------
   Responsive shell
   -------------------------------------------------------------------------- */

@media (max-width: 1100px) {
  :root {
    --gutter: 36px;
  }

  .site-nav {
    gap: 22px;
  }
}

@media (max-width: 900px) {
  :root {
    --gutter: 24px;
  }

  .site-nav {
    display: none;
  }

  .nav-toggle {
    display: inline-flex;
    align-items: center;
  }

  .site-head__in {
    gap: 16px;
  }

  .site-head.is-open .site-nav {
    display: flex;
    position: fixed;
    top: var(--head-h);
    left: 0;
    right: 0;
    z-index: 55;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 8px var(--gutter) 20px;
    background: var(--paper);
    border-bottom: 1px solid var(--ink);
  }

  .site-head.is-open .site-nav a {
    padding: 14px 0;
    border-bottom: 1px solid var(--line-2);
    font-size: 16px;
  }

  .site-head.is-open .site-nav a::after {
    display: none;
  }

  .section {
    padding: 72px 0;
  }

  .foot-meta {
    text-align: left;
  }
}

@media (max-width: 600px) {
  :root {
    --gutter: 20px;
  }

  body {
    font-size: 15.5px;
  }

  .brand__text em {
    display: none;
  }

  .site-head__actions .btn {
    width: 38px;
    padding: 0;
  }

  .site-head__actions .btn__label {
    display: none;
  }

  .section {
    padding: 60px 0;
  }

  .site-foot__in {
    gap: 24px;
  }
}