@import url('https://fonts.googleapis.com/css2?family=DM+Sans:wght@400;500;700&family=Space+Grotesk:wght@400;500;600;700&display=swap');

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

:root {
  --ink: #1f1f1f;
  --paper: #ffffff;
  --layer: #f5f5f5;
  --line: #e3e3e3;
  --line-2: #d5d5d5;
  --muted: #6b6b6b;
  --r: 4px;
  --gut: clamp(16px, 4vw, 44px);
  --e1: 0 1px 2px rgba(31, 31, 31, 0.07);
  --e2: 0 6px 18px -10px rgba(31, 31, 31, 0.18);
  --e3: 0 16px 36px -14px rgba(31, 31, 31, 0.24);
  --e4: 0 30px 64px -22px rgba(31, 31, 31, 0.3);
  --stack-1: 1;
  --stack-2: 2;
  --stack-3: 3;
  --stack-4: 4;
}

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

body {
  margin: 0;
  overflow-x: hidden;
  font-family: "DM Sans", "Space Grotesk", system-ui, -apple-system, "Segoe UI",
    "Noto Sans SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 17px;
  line-height: 1.68;
  color: var(--ink);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3,
h4 {
  font-family: "Space Grotesk", "DM Sans", system-ui, "Noto Sans SC", sans-serif;
  line-height: 1.22;
  letter-spacing: -0.02em;
  margin: 0 0 0.5em;
}

p {
  margin: 0 0 1.05em;
}

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

a {
  color: var(--ink);
}

[id] {
  scroll-margin-top: 22px;
}

/* ---------- 顶条 ---------- */

.topbar {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 7px var(--gut);
  background: var(--ink);
  color: #fff;
  font-family: "Space Grotesk", system-ui, sans-serif;
  font-size: 15px;
  letter-spacing: 0.03em;
  position: relative;
  z-index: var(--stack-4);
}

.topbar .tick {
  min-width: 0;
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
}

.topbar .tick::before {
  content: "";
  display: inline-block;
  width: 7px;
  height: 7px;
  margin-right: 10px;
  border-radius: 50%;
  background: #fff;
  vertical-align: middle;
  transform: translateY(-1px);
}

/* ---------- 页头 ---------- */

.masthead {
  position: relative;
  z-index: var(--stack-3);
  background: rgba(255, 255, 255, 0.9);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line);
}

.brandrow {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px var(--gut) 10px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-height: 44px;
  text-decoration: none;
  color: var(--ink);
}

.mark {
  flex: 0 0 auto;
  width: 32px;
  height: 32px;
  border-radius: var(--r);
  background: var(--ink);
  color: #fff;
  display: grid;
  place-items: center;
  font-family: "Space Grotesk", sans-serif;
  font-weight: 700;
  font-size: 17px;
  object-fit: cover;
}

.brandname {
  font-family: "Space Grotesk", "DM Sans", system-ui, sans-serif;
  font-weight: 700;
  font-size: 20px;
  letter-spacing: -0.01em;
}

.toplink {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 0 12px;
  font-size: 15px;
  text-decoration: none;
  color: var(--ink);
  border: 1px solid var(--line-2);
  border-radius: var(--r);
  background: #fff;
  transition: background 0.18s ease, transform 0.18s ease, box-shadow 0.18s ease;
}

.toplink:hover {
  background: var(--layer);
  transform: translateY(-1px);
  box-shadow: var(--e1);
}

.menubar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 2px;
  padding: 0 var(--gut) 10px;
  position: relative;
  z-index: var(--stack-2);
}

.menu-link {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 12px;
  font-size: 16px;
  text-decoration: none;
  color: var(--ink);
  border: 1px solid transparent;
  border-radius: var(--r);
  transition: background 0.18s ease, border-color 0.18s ease, transform 0.18s ease;
}

.menu-link:hover,
.menu-link:focus-visible {
  background: var(--layer);
  border-color: var(--ink);
  transform: translateY(-1px);
}

/* ---------- 首屏 ---------- */

.hero {
  position: relative;
  z-index: var(--stack-1);
  display: grid;
  gap: clamp(22px, 4vw, 52px);
  align-items: center;
  padding: clamp(26px, 5vw, 58px) var(--gut) clamp(62px, 8vw, 104px);
  min-height: clamp(540px, 92svh, 100svh);
  overflow: hidden;
  background: linear-gradient(180deg, #ffffff 0%, #f5f5f5 100%);
}

.hero::after {
  content: "";
  position: absolute;
  left: -12%;
  right: -12%;
  bottom: -34px;
  height: 88px;
  background: var(--ink);
  transform: skewY(-3deg);
  transform-origin: 100% 100%;
  z-index: 0;
}

.hero-txt {
  position: relative;
  z-index: var(--stack-3);
  text-align: center;
}

.hero h1 {
  font-size: clamp(1.95rem, 5.6vw, 3.5rem);
  letter-spacing: -0.035em;
  margin-bottom: 0.35em;
}

.lede {
  max-width: 40ch;
  margin: 0 auto 1.5em;
  color: #3a3a3a;
  font-size: 17px;
}

.cta {
  display: inline-flex;
  align-items: center;
  min-height: 48px;
  padding: 0 24px;
  border-radius: var(--r);
  background: var(--ink);
  color: #fff;
  text-decoration: none;
  font-family: "Space Grotesk", sans-serif;
  font-weight: 600;
  font-size: 16px;
  letter-spacing: 0.03em;
  box-shadow: var(--e2);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.cta:hover {
  transform: translateY(-2px);
  box-shadow: var(--e3);
}

.hero-art {
  position: relative;
  z-index: var(--stack-2);
  aspect-ratio: 16 / 11;
  max-height: 480px;
}

.hero-art::before {
  content: "";
  position: absolute;
  inset: 18px -12px -12px 18px;
  background: #ffffff;
  border: 1px solid var(--ink);
  border-radius: var(--r);
  z-index: var(--stack-1);
  box-shadow: var(--e2);
}

.plate {
  position: absolute;
  inset: 0;
  margin: 0;
  border: 1px solid var(--ink);
  border-radius: var(--r);
  overflow: hidden;
  background: #fff;
  box-shadow: var(--e4);
  z-index: var(--stack-2);
}

.plate img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.plate-void {
  background: repeating-linear-gradient(
    135deg,
    #ffffff 0,
    #ffffff 13px,
    #f0f0f0 13px,
    #f0f0f0 14px
  );
}

/* ---------- 主体骨架 ---------- */

.wrap {
  width: 100%;
  max-width: 1180px;
  margin: 0 auto;
  padding: clamp(30px, 5vw, 64px) var(--gut);
}

.frame {
  display: grid;
  gap: clamp(20px, 3vw, 44px);
  align-items: start;
  position: relative;
}

/* ---------- 侧栏 ---------- */

.rail {
  position: relative;
  z-index: var(--stack-2);
  border: 1px solid var(--line);
  border-radius: var(--r);
  background: #fff;
  padding: 16px 14px 18px;
}

.rail-t {
  font-size: 17px;
  letter-spacing: 0.06em;
  margin: 0 0 10px;
}

.rail hr {
  width: 46px;
  margin: 0 0 12px;
  border: 0;
  border-top: 2px solid var(--ink);
}

.rail-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.rail-list a {
  display: flex;
  align-items: center;
  min-height: 40px;
  padding: 0 8px;
  font-size: 16px;
  text-decoration: none;
  color: var(--ink);
  border-left: 2px solid transparent;
  border-radius: 0 var(--r) var(--r) 0;
  transition: background 0.16s ease, border-color 0.16s ease;
}

.rail-list a:hover,
.rail-list a:focus-visible {
  background: var(--layer);
  border-left-color: var(--ink);
}

/* ---------- 正文 ---------- */

.doc {
  position: relative;
  z-index: var(--stack-1);
  max-width: 74ch;
  font-size: 17px;
}

.doc > div {
  padding-block: clamp(20px, 3.2vw, 34px);
  border-top: 1px solid var(--line-2);
}

.doc > div:first-child {
  border-top: 0;
  padding-top: 0;
}

.doc h2 {
  font-size: clamp(1.4rem, 2.8vw, 1.9rem);
  margin-top: 0.15em;
}

.doc h3 {
  font-size: clamp(1.12rem, 2.1vw, 1.32rem);
  margin-top: 1.5em;
}

.doc hr {
  width: 100%;
  margin: 0 0 1.2em;
  border: 0;
  border-top: 1px solid var(--line-2);
}

.doc a {
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.doc ul,
.doc ol {
  margin: 0 0 1.1em;
  padding-left: 1.3em;
}

.doc li {
  margin-bottom: 0.4em;
}

.doc img {
  border: 1px solid var(--line);
  border-radius: var(--r);
}

.doc blockquote {
  margin: 0 0 1.15em;
  padding: 14px 18px;
  background: var(--layer);
  border-left: 3px solid var(--ink);
  border-radius: 0 var(--r) var(--r) 0;
}

.doc table {
  width: 100%;
  border-collapse: collapse;
  font-size: 16px;
  margin-bottom: 1.2em;
}

.doc th,
.doc td {
  border: 1px solid var(--line-2);
  padding: 9px 11px;
  text-align: left;
}

.doc th {
  background: var(--layer);
}

.doc pre {
  overflow-x: auto;
  padding: 14px 16px;
  border: 1px solid var(--line-2);
  border-radius: var(--r);
  background: var(--layer);
}

/* ---------- 页脚 ---------- */

footer {
  position: relative;
  z-index: var(--stack-3);
  margin-top: clamp(32px, 6vw, 76px);
  padding: 28px var(--gut) 34px;
  display: flex;
  flex-wrap: wrap;
  gap: 26px 38px;
  align-items: flex-start;
  justify-content: space-between;
  background: var(--layer);
  border-top: 2px solid var(--ink);
}

.f-brand {
  flex: 0 0 auto;
}

.f-nav dl {
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 2px 18px;
  max-width: 34rem;
}

.f-nav dt {
  width: 100%;
  font-size: 15px;
  letter-spacing: 0.1em;
  color: var(--muted);
  margin-bottom: 2px;
}

.f-nav dd {
  margin: 0;
}

.f-nav a {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  font-size: 16px;
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.16s ease;
}

.f-nav a:hover,
.f-nav a:focus-visible {
  border-bottom-color: var(--ink);
}

.f-form {
  flex: 1 1 260px;
}

.sub {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.sub label {
  width: 100%;
  font-size: 15px;
  letter-spacing: 0.1em;
  color: var(--muted);
}

.sub input {
  flex: 1 1 150px;
  min-width: 0;
  min-height: 44px;
  padding: 0 12px;
  font: inherit;
  font-size: 16px;
  color: var(--ink);
  background: #fff;
  border: 1px solid var(--ink);
  border-radius: var(--r);
}

.sub button {
  min-height: 44px;
  padding: 0 18px;
  font: inherit;
  font-size: 16px;
  color: #fff;
  background: var(--ink);
  border: 1px solid var(--ink);
  border-radius: var(--r);
  cursor: pointer;
  transition: transform 0.18s ease, box-shadow 0.18s ease;
}

.sub button:hover {
  transform: translateY(-1px);
  box-shadow: var(--e2);
}

.f-legal {
  flex: 1 1 220px;
  min-width: 190px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 18px;
  padding-top: 6px;
  border-top: 1px solid var(--line-2);
}

.f-legal p {
  margin: 0;
  font-size: 16px;
  color: var(--muted);
}

.f-legal a {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  font-size: 15px;
  text-decoration: none;
  border-bottom: 1px solid var(--ink);
}

/* ---------- 动效 ---------- */

.rv {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.55s ease, transform 0.55s cubic-bezier(0.2, 0.7, 0.3, 1);
}

.rv.in {
  opacity: 1;
  transform: none;
}

/* ---------- 断点 ---------- */

@media (min-width: 900px) {
  .masthead {
    position: sticky;
    top: 0;
    box-shadow: var(--e1);
  }

  [id] {
    scroll-margin-top: 132px;
  }

  .hero {
    grid-template-columns: minmax(0, 1.02fr) minmax(0, 0.98fr);
  }

  .frame {
    grid-template-columns: minmax(0, 240px) minmax(0, 1fr);
  }

  .rail {
    position: sticky;
    top: 128px;
  }
}

@media (max-width: 899px) {
  .rail {
    order: 2;
  }

  .doc {
    order: 1;
  }
}

@media (max-width: 640px) {
  body {
    font-size: 16.5px;
  }

  .hero {
    min-height: auto;
    padding-bottom: 78px;
  }

  .hero-art {
    aspect-ratio: 16 / 10;
  }

  .brandname {
    font-size: 18px;
  }

  footer {
    flex-direction: column;
    gap: 20px;
  }

  .f-legal {
    width: 100%;
  }
}

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

  .rv {
    opacity: 1;
    transform: none;
  }

  *,
  *::before,
  *::after {
    transition-duration: 0.001ms !important;
    animation-duration: 0.001ms !important;
  }
}

button[aria-expanded]{min-width:44px;min-height:44px}