/* PoHW — Proof of Homework · 宣传首页样式
   纯静态、零依赖；配色对齐 APP 图标：深蓝底 / 琥珀计时弧 / 青绿对勾 */

:root {
  --bg: #0F1725;
  --bg-2: #161E2B;
  --bg-3: #1C2738;
  --amber: #E8A33D;
  --mint: #1D9E75;
  --text: #F5F7FA;
  --muted: #A6B2C3;
  --border: rgba(245, 247, 250, 0.10);
  --border-strong: rgba(245, 247, 250, 0.20);
  --red: #A32D2D;
  --maxw: 1120px;
  --radius: 16px;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", "Source Han Sans SC", "WenQuanYi Micro Hei", sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 88px; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  line-height: 1.75;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  background-image:
    radial-gradient(900px 520px at 12% -8%, rgba(29, 158, 117, 0.10), transparent 70%),
    radial-gradient(760px 480px at 92% 4%, rgba(232, 163, 61, 0.09), transparent 70%);
  background-attachment: fixed;
}

a { color: var(--amber); text-decoration: none; transition: color .18s ease, opacity .18s ease; }
a:hover { color: #F3BE6B; }

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

h1, h2, h3, h4 { line-height: 1.35; margin: 0; font-weight: 700; letter-spacing: .01em; }
p { margin: 0; }
ul, ol { margin: 0; padding: 0; }

code, .mono { font-family: var(--mono); font-size: .9em; }

code {
  background: rgba(245, 247, 250, .07);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: .1em .4em;
  color: #F3BE6B;
  word-break: break-word;
}

.container { width: 100%; max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }

.section { padding: 88px 0; border-top: 1px solid var(--border); }
.section:nth-of-type(even) { background: rgba(22, 30, 43, .35); }

.section-head { max-width: 760px; margin-bottom: 44px; }
.section-title { font-size: clamp(26px, 3.4vw, 38px); margin: 10px 0 14px; }
.section-lead { color: var(--muted); font-size: 16px; }
.section-lead a { text-decoration: underline; text-underline-offset: 3px; }

.eyebrow {
  display: inline-block;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--mint);
  border: 1px solid rgba(29, 158, 117, .35);
  background: rgba(29, 158, 117, .08);
  border-radius: 999px;
  padding: 4px 14px;
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 24px;
  border-radius: 10px;
  font-size: 15px;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform .18s ease, box-shadow .18s ease, background .18s ease, color .18s ease, border-color .18s ease;
  white-space: nowrap;
}
.btn:hover { transform: translateY(-2px); }
.btn-primary {
  background: var(--amber);
  color: #141C29;
  box-shadow: 0 8px 26px rgba(232, 163, 61, .22);
}
.btn-primary:hover { background: #F3BE6B; color: #101825; box-shadow: 0 12px 32px rgba(232, 163, 61, .32); }
.btn-ghost {
  background: rgba(245, 247, 250, .03);
  color: var(--text);
  border-color: var(--border-strong);
}
.btn-ghost:hover { background: rgba(245, 247, 250, .08); color: var(--text); border-color: rgba(245, 247, 250, .35); }
.btn-sm { padding: 9px 18px; font-size: 14px; }
.btn-lg { padding: 16px 30px; font-size: 16px; }

/* ---------- 顶部导航 ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(15, 23, 37, .82);
  backdrop-filter: saturate(160%) blur(14px);
  -webkit-backdrop-filter: saturate(160%) blur(14px);
  border-bottom: 1px solid var(--border);
}
.nav-inner { display: flex; align-items: center; gap: 24px; height: 68px; }
.brand { display: inline-flex; align-items: center; gap: 10px; color: var(--text); flex-shrink: 0; }
.brand:hover { color: var(--text); }
.brand img { width: 34px; height: 34px; border-radius: 9px; }
.brand-name { font-family: var(--mono); font-size: 19px; font-weight: 700; letter-spacing: .04em; }
.brand-sub { color: var(--muted); font-size: 12px; letter-spacing: .03em; }
.nav-links { display: flex; align-items: center; gap: 4px; margin-left: auto; }
.nav-links a {
  color: var(--muted);
  font-size: 14px;
  padding: 7px 12px;
  border-radius: 8px;
  white-space: nowrap;
}
.nav-links a:hover { color: var(--text); background: rgba(245, 247, 250, .06); }
.nav-links a.active { color: var(--amber); background: rgba(232, 163, 61, .10); }
.nav .btn-sm { flex-shrink: 0; }

/* ---------- Hero ---------- */
.hero { padding: 80px 0 72px; }
.hero-grid { display: grid; grid-template-columns: 1.15fr .85fr; gap: 56px; align-items: center; }
.hero-title { font-size: clamp(46px, 7vw, 82px); letter-spacing: -.02em; line-height: 1.05; }
.hero-title-en {
  display: block;
  font-family: var(--mono);
  font-size: clamp(16px, 2.1vw, 24px);
  font-weight: 500;
  letter-spacing: .12em;
  color: var(--mint);
  margin-top: 14px;
}
.hero-tagline {
  font-size: clamp(20px, 2.6vw, 28px);
  color: var(--amber);
  font-weight: 600;
  margin: 26px 0 16px;
}
.hero-desc { color: #DCE3ED; font-size: 16px; max-width: 620px; }
.hero-note { color: var(--muted); font-size: 14px; margin-top: 14px; max-width: 620px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 14px; margin-top: 32px; }
.hero-facts { display: flex; flex-wrap: wrap; gap: 10px 22px; margin-top: 30px; }
.hero-facts span {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--muted);
  padding-left: 14px;
  position: relative;
}
.hero-facts span::before {
  content: "";
  position: absolute; left: 0; top: 50%;
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--mint);
  transform: translateY(-50%);
}

/* 电视 + 计时弧 + 对勾（纯 CSS 示意图） */
.hero-art { max-width: 420px; width: 100%; margin: 0 auto; }
.tv-art { filter: drop-shadow(0 30px 50px rgba(0, 0, 0, .45)); }
.tv-screen {
  position: relative;
  aspect-ratio: 16 / 10;
  border-radius: 22px;
  background:
    radial-gradient(130% 120% at 28% 18%, #24344B 0%, var(--bg-2) 55%, #0C1420 100%);
  border: 1px solid var(--border-strong);
  box-shadow:
    0 0 0 7px rgba(245, 247, 250, .025),
    inset 0 0 70px rgba(29, 158, 117, .07),
    inset 0 1px 0 rgba(255, 255, 255, .06);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}
.tv-screen::before {
  content: "";
  position: absolute; inset: 0;
  background: repeating-linear-gradient(0deg, rgba(255, 255, 255, .018) 0 1px, transparent 1px 4px);
  pointer-events: none;
}
.tv-screen::after {
  content: "";
  position: absolute;
  top: -40%; left: -20%;
  width: 60%; height: 180%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, .035), transparent);
  transform: rotate(18deg);
  pointer-events: none;
}
.tv-dial { position: relative; width: 118px; height: 118px; z-index: 2; }
.tv-arc {
  position: absolute; inset: 0;
  border-radius: 50%;
  background: conic-gradient(from -90deg,
      var(--amber) 0deg, var(--amber) 258deg,
      rgba(232, 163, 61, .10) 258deg, rgba(232, 163, 61, .10) 360deg);
  animation: tv-spin 16s linear infinite;
  box-shadow: 0 0 26px rgba(232, 163, 61, .22);
}
.tv-arc::after {
  content: "";
  position: absolute; inset: 13px;
  border-radius: 50%;
  background: var(--bg-2);
  box-shadow: inset 0 0 20px rgba(0, 0, 0, .5);
}
.tv-check {
  position: absolute;
  left: 50%; top: 47%;
  width: 24px; height: 44px;
  border-right: 7px solid var(--mint);
  border-bottom: 7px solid var(--mint);
  border-radius: 3px;
  transform: translate(-50%, -50%) rotate(45deg);
  z-index: 3;
  filter: drop-shadow(0 0 10px rgba(29, 158, 117, .55));
}
.tv-caption {
  position: absolute;
  bottom: 16px; left: 0; right: 0;
  text-align: center;
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--muted);
  z-index: 2;
}
.tv-neck {
  width: 66px; height: 16px;
  margin: 0 auto;
  background: linear-gradient(180deg, #1C2738, #121B29);
  border: 1px solid var(--border);
  border-top: none;
}
.tv-base {
  width: 180px; height: 10px;
  margin: 0 auto;
  border-radius: 0 0 12px 12px;
  background: linear-gradient(180deg, #22304A, #101825);
  border: 1px solid var(--border);
  border-top: none;
}
.art-caption { text-align: center; color: var(--muted); font-size: 12px; margin-top: 18px; letter-spacing: .08em; }
@keyframes tv-spin { to { transform: rotate(360deg); } }

/* ---------- 品牌资源展示 ---------- */
.brand-strip { border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); background: rgba(22, 30, 43, .5); padding: 34px 0; }
.brand-strip-inner { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; align-items: center; }
.brand-strip-copy { display: flex; align-items: center; gap: 20px; }
.brand-strip-copy img { width: 76px; height: 76px; border-radius: 18px; flex-shrink: 0; box-shadow: 0 10px 30px rgba(0, 0, 0, .4); }
.brand-strip-copy h2 { font-size: 19px; margin-bottom: 8px; }
.brand-strip-copy p { color: var(--muted); font-size: 14px; }
.banner {
  width: 100%;
  border-radius: 12px;
  border: 1px solid var(--border-strong);
  box-shadow: 0 16px 40px rgba(0, 0, 0, .4);
}
.banner-label { color: var(--muted); font-size: 12px; font-family: var(--mono); margin-top: 8px; text-align: center; }

/* ---------- 产品亮点 ---------- */
.features-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }
.feature-card {
  position: relative;
  background: linear-gradient(160deg, rgba(28, 39, 56, .75), rgba(22, 30, 43, .55));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px 26px 24px;
  transition: transform .2s ease, border-color .2s ease, box-shadow .2s ease;
  overflow: hidden;
}
.feature-card::before {
  content: "";
  position: absolute; top: 0; left: 0; width: 44px; height: 3px;
  background: var(--amber);
  border-radius: 0 0 3px 0;
}
.feature-card:nth-child(3n)::before { background: var(--mint); }
.feature-card:hover { transform: translateY(-4px); border-color: var(--border-strong); box-shadow: 0 18px 40px rgba(0, 0, 0, .3); }
.feature-no { font-family: var(--mono); font-size: 12px; color: var(--amber); letter-spacing: .1em; }
.feature-card h3 { font-size: 18px; margin: 10px 0 10px; }
.feature-card p { color: var(--muted); font-size: 14px; }
.tag {
  display: inline-block;
  margin-top: 16px;
  font-family: var(--mono);
  font-size: 11px;
  color: var(--mint);
  background: rgba(29, 158, 117, .10);
  border: 1px solid rgba(29, 158, 117, .28);
  border-radius: 6px;
  padding: 3px 9px;
}
.tag.warn { color: var(--amber); background: rgba(232, 163, 61, .10); border-color: rgba(232, 163, 61, .30); }

/* ---------- 安装步骤 ---------- */
.steps { list-style: none; display: grid; gap: 14px; counter-reset: step; }
.step {
  display: grid;
  grid-template-columns: 52px 1fr;
  gap: 20px;
  background: rgba(22, 30, 43, .6);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px 24px;
}
.step-no {
  width: 44px; height: 44px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 12px;
  background: rgba(232, 163, 61, .12);
  border: 1px solid rgba(232, 163, 61, .35);
  color: var(--amber);
  font-family: var(--mono);
  font-size: 18px; font-weight: 700;
}
.step h3 { font-size: 17px; margin-bottom: 6px; }
.step p { color: var(--muted); font-size: 14px; }
.step code { display: inline-block; margin-top: 10px; font-size: 12px; }
.callout {
  margin-top: 26px;
  border: 1px solid rgba(232, 163, 61, .30);
  background: rgba(232, 163, 61, .07);
  border-radius: 12px;
  padding: 22px 26px;
}
.callout h3 { font-size: 16px; color: var(--amber); margin-bottom: 12px; }
.callout ul { list-style: none; display: grid; gap: 8px; }
.callout li { color: #DCE3ED; font-size: 14px; padding-left: 18px; position: relative; }
.callout li::before { content: "—"; position: absolute; left: 0; color: var(--amber); }
.callout code { font-size: 12px; }

/* ---------- 下载 ---------- */
.download-section { background: radial-gradient(700px 340px at 50% 0%, rgba(232, 163, 61, .10), transparent 70%); }
.download-box {
  border: 1px solid var(--border-strong);
  background: linear-gradient(150deg, rgba(28, 39, 56, .85), rgba(15, 23, 37, .85));
  border-radius: 20px;
  padding: 48px 44px;
  text-align: center;
  box-shadow: 0 24px 60px rgba(0, 0, 0, .35);
}
.download-box .section-title { margin: 14px 0 14px; }
.download-box > p { color: var(--muted); max-width: 720px; margin: 0 auto; font-size: 15px; }
.download-box strong { color: var(--text); }
.download-actions { display: flex; flex-wrap: wrap; gap: 14px; justify-content: center; margin-top: 30px; }
.download-hint { color: var(--muted); font-size: 13px; margin-top: 24px !important; }

/* ---------- 版本更新记录 ---------- */
.releases { position: relative; padding-left: 26px; }
.releases::before { content: ""; position: absolute; left: 6px; top: 8px; bottom: 8px; width: 2px; background: linear-gradient(180deg, var(--amber), rgba(29, 158, 117, .5), var(--border)); }
.release { position: relative; display: grid; grid-template-columns: 190px 1fr; gap: 28px; padding: 0 0 30px; }
.release::before {
  content: "";
  position: absolute;
  left: -24px; top: 10px;
  width: 11px; height: 11px;
  border-radius: 50%;
  background: var(--bg);
  border: 2px solid var(--mint);
  box-shadow: 0 0 0 4px rgba(29, 158, 117, .10);
}
.release:first-child::before { border-color: var(--amber); box-shadow: 0 0 0 4px rgba(232, 163, 61, .14); }
.release-meta { display: flex; flex-direction: column; align-items: flex-start; gap: 8px; }
.release-version { font-family: var(--mono); font-size: 16px; font-weight: 700; color: var(--amber); }
.release-code { font-family: var(--mono); font-size: 11px; color: var(--muted); border: 1px solid var(--border); border-radius: 5px; padding: 1px 7px; }
.release-badge { font-size: 11px; color: #141C29; background: var(--amber); border-radius: 5px; padding: 2px 9px; font-weight: 700; letter-spacing: .05em; }
.release-body {
  background: rgba(22, 30, 43, .55);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px 24px;
}
.release-title { font-size: 17px; margin-bottom: 12px; }
.release-body ul { list-style: none; display: grid; gap: 8px; }
.release-body li { color: var(--muted); font-size: 14px; padding-left: 16px; position: relative; }
.release-body li::before { content: "·"; position: absolute; left: 2px; color: var(--mint); font-weight: 700; }
.release-note { margin-top: 14px; font-size: 13px; color: var(--amber); border-left: 2px solid rgba(232, 163, 61, .5); padding-left: 12px; }

/* ---------- FAQ ---------- */
.faq-list { display: grid; gap: 12px; max-width: 900px; }
.faq-item {
  border: 1px solid var(--border);
  border-radius: 12px;
  background: rgba(22, 30, 43, .55);
  overflow: hidden;
}
.faq-item summary {
  cursor: pointer;
  padding: 18px 22px;
  font-size: 16px;
  font-weight: 600;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 14px;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::before {
  content: "+";
  font-family: var(--mono);
  color: var(--mint);
  font-size: 20px;
  width: 18px;
  flex-shrink: 0;
}
.faq-item[open] summary::before { content: "−"; color: var(--amber); }
.faq-item[open] summary { border-bottom: 1px solid var(--border); }
.faq-item p { padding: 16px 22px 20px 54px; color: var(--muted); font-size: 14px; }
.faq-item p a { text-decoration: underline; text-underline-offset: 3px; }

/* ---------- 文档 ---------- */
.docs-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.doc-card {
  display: block;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: rgba(22, 30, 43, .55);
  padding: 22px;
  color: var(--text);
  transition: transform .18s ease, border-color .18s ease, background .18s ease;
}
.doc-card:hover { transform: translateY(-3px); border-color: rgba(232, 163, 61, .45); background: rgba(28, 39, 56, .8); color: var(--text); }
.doc-card .doc-path { font-family: var(--mono); font-size: 12px; color: var(--amber); word-break: break-all; }
.doc-card h3 { font-size: 16px; margin: 10px 0 8px; }
.doc-card p { color: var(--muted); font-size: 13px; }
.doc-card .doc-arrow { display: inline-block; margin-top: 12px; color: var(--mint); font-size: 13px; font-family: var(--mono); }

/* ---------- 页脚 ---------- */
.footer { border-top: 1px solid var(--border); background: rgba(10, 16, 26, .6); padding: 44px 0 32px; }
.footer-inner { display: flex; flex-wrap: wrap; gap: 24px; justify-content: space-between; align-items: flex-start; }
.footer-brand { display: flex; align-items: center; gap: 12px; }
.footer-brand img { width: 40px; height: 40px; border-radius: 10px; }
.footer-brand strong { font-family: var(--mono); font-size: 16px; }
.footer-brand span { display: block; color: var(--muted); font-size: 12px; }
.footer p { color: var(--muted); font-size: 13px; max-width: 620px; }
.footer-links { display: flex; flex-wrap: wrap; gap: 8px 20px; font-size: 13px; }
.footer-bottom { margin-top: 28px; padding-top: 20px; border-top: 1px solid var(--border); color: var(--muted); font-size: 12px; display: flex; flex-wrap: wrap; gap: 8px 20px; justify-content: space-between; }
.footer-bottom a { color: var(--muted); text-decoration: underline; text-underline-offset: 2px; }
.footer-bottom a:hover { color: var(--amber); }

/* ---------- 响应式 ---------- */
@media (max-width: 980px) {
  .hero-grid { grid-template-columns: 1fr; gap: 48px; }
  .hero-art { max-width: 380px; }
  .brand-strip-inner { grid-template-columns: 1fr; gap: 26px; }
  .docs-grid { grid-template-columns: repeat(2, 1fr); }
  .release { grid-template-columns: 150px 1fr; gap: 20px; }
}

@media (max-width: 760px) {
  .section { padding: 64px 0; }
  .nav-links { display: none; }
  .nav-inner { gap: 12px; }
  .nav .btn-sm { margin-left: auto; }
  .brand-sub { display: none; }
  .features-grid { grid-template-columns: 1fr; }
  .docs-grid { grid-template-columns: 1fr; }
  .download-box { padding: 34px 22px; }
  .release { grid-template-columns: 1fr; gap: 12px; }
  .release-meta { flex-direction: row; flex-wrap: wrap; align-items: center; }
  .step { grid-template-columns: 42px 1fr; gap: 14px; padding: 18px; }
  .step-no { width: 38px; height: 38px; font-size: 16px; }
  .faq-item p { padding-left: 22px; }
}

@media (max-width: 480px) {
  .container { padding: 0 18px; }
  .hero { padding: 56px 0 52px; }
  .btn-lg { width: 100%; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .001ms !important; animation-iteration-count: 1 !important; transition-duration: .001ms !important; }
}