/* Tangyuan Math — 公开页面样式（红白可爱主题，零第三方资源） */
:root {
  --red: #F2555A;
  --red-deep: #D93B47;
  --red-dark: #B02A37;
  --red-light: #FFE9E6;
  --pink: #FFC2CC;
  --pink-light: #FFDAD4;
  --cream: #FFF7F2;
  --ink: #5D3A3A;
  --ink-soft: #9A7070;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
  font-family: system-ui, -apple-system, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  background: var(--cream);
  background-image: radial-gradient(rgba(242, 85, 90, .07) 2.5px, transparent 2.6px);
  background-size: 30px 30px;
  color: var(--ink);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  line-height: 1.65;
}

:focus-visible { outline: 3px solid var(--red-deep); outline-offset: 2px; border-radius: 6px; }

/* 图标：Phosphor 自托管 SVG，随字号缩放、随文字颜色着色 */
.ico { width: 1em; height: 1em; fill: currentColor; flex-shrink: 0; vertical-align: -0.125em; }

.wrap { width: 100%; max-width: 880px; margin: 0 auto; padding: 0 20px; }

/* ---------- 头部 ---------- */
.site-header {
  background: #fff;
  border-bottom: 2px solid var(--red-light);
  position: sticky; top: 0; z-index: 10;
}
.site-header .wrap {
  display: flex; align-items: center; justify-content: space-between;
  gap: 14px; flex-wrap: wrap; padding-top: 12px; padding-bottom: 12px;
}
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; }
.brand img {
  width: 42px; height: 42px; border-radius: 15px; border: 2px solid #fff;
  box-shadow: 0 0 0 2px var(--pink); background: #fff;
}
.brand b {
  font-size: 18px; font-weight: 900;
  background: linear-gradient(120deg, var(--red-dark), var(--red) 60%, #FF8A8E);
  -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
}
.site-nav { display: flex; gap: 6px; flex-wrap: wrap; align-items: center; }
.site-nav a {
  display: inline-flex; align-items: center; gap: 6px;
  text-decoration: none; font-weight: 800; font-size: 14px;
  color: var(--red-deep); padding: 8px 14px; border-radius: 999px;
  border: 2px solid transparent;
}
.site-nav a:hover { background: var(--red-light); }
.site-nav a[aria-current="page"] { background: var(--red-light); border-color: var(--pink); }
.site-nav .play-cta {
  background: linear-gradient(180deg, #FF7B7B, var(--red)); color: #fff;
  box-shadow: 0 3px 0 var(--red-dark);
}
.site-nav .play-cta:hover { background: linear-gradient(180deg, #FF7B7B, var(--red)); transform: translateY(-1px); }
.site-nav .lang-switch { border: 2px solid var(--pink); background: #fff; }

/* ---------- 主体 ---------- */
main { flex: 1; padding: 40px 0 56px; }

.hero { text-align: center; padding: 26px 0 34px; }
.hero .hero-mascot {
  width: 132px; height: 132px; border-radius: 44px; border: 4px solid #fff;
  box-shadow: 0 14px 34px rgba(217, 59, 71, .25), 0 0 0 3px var(--pink);
  background: #fff;
}
.hero h1 { font-size: 34px; font-weight: 900; margin-top: 16px; letter-spacing: .5px;
  background: linear-gradient(120deg, var(--red-dark), var(--red) 55%, #FF8A8E);
  -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
}
.hero .tagline { font-size: 17px; font-weight: 800; color: var(--red-deep); margin-top: 6px; }
.hero .sub { font-size: 15px; color: var(--ink-soft); font-weight: 600; margin-top: 10px; }
.hero .badges { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; margin-top: 16px; }
.badge-pill {
  display: inline-flex; align-items: center; gap: 6px;
  background: #fff; border: 2px solid var(--pink); color: var(--red-deep);
  font-size: 13px; font-weight: 800; padding: 7px 16px; border-radius: 999px;
}
.hero .cta-row { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; margin-top: 24px; }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  text-decoration: none; text-align: center; cursor: pointer;
  font: 900 16px/1 inherit; letter-spacing: .4px;
  padding: 15px 36px; border-radius: 999px; border: none;
  transition: transform .1s, box-shadow .15s;
}
.btn:active { transform: translateY(2px); }
.btn-primary {
  background: linear-gradient(180deg, #FF7B7B, var(--red)); color: #fff;
  box-shadow: 0 4px 0 var(--red-dark), 0 10px 24px rgba(242, 85, 90, .3);
}
.btn-primary:active { box-shadow: 0 1px 0 var(--red-dark); }
.btn-ghost {
  background: #fff; color: var(--red-deep); border: 2px solid var(--pink);
  box-shadow: 0 4px 0 var(--pink-light);
}

/* ---------- 区块 ---------- */
section.block { margin: 34px 0; }
section.block > h1, section.block > h2 {
  font-size: 22px; font-weight: 900; color: var(--red-deep);
  margin-bottom: 14px; display: flex; align-items: center; gap: 8px;
}
.card-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 14px; }
.info-card {
  background: #fff; border: 2px solid var(--red-light); border-radius: 20px;
  padding: 20px 18px; box-shadow: 0 6px 16px rgba(217, 59, 71, .07);
}
.info-card .ico { font-size: 26px; color: var(--red); }
.info-card h3 { font-size: 16px; color: var(--red-deep); margin: 8px 0 6px; }
.info-card p { font-size: 14px; color: var(--ink-soft); font-weight: 600; }

.prose { background: #fff; border: 2px solid var(--red-light); border-radius: 22px;
  padding: 26px 30px; box-shadow: 0 6px 16px rgba(217, 59, 71, .07); }
.prose h2 { font-size: 20px; color: var(--red-deep); margin: 22px 0 10px; }
.prose h2:first-child { margin-top: 0; }
.prose p, .prose li { font-size: 15px; color: var(--ink); }
.prose ul { padding-left: 22px; margin: 8px 0; }
.prose li { margin: 6px 0; }
.prose .muted { color: var(--ink-soft); font-size: 13.5px; }

.faq-item { border-bottom: 2px dashed var(--pink-light); padding: 14px 0; }
.faq-item:last-child { border-bottom: none; }
.faq-item h2 { font-size: 16px; color: var(--red-deep); margin-bottom: 6px; }
.faq-item p { font-size: 14.5px; color: var(--ink); }

/* 语言入口页 */
.lang-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 16px; margin-top: 28px; }
.lang-card {
  display: block; text-decoration: none; background: #fff;
  border: 2px solid var(--red-light); border-radius: 24px; padding: 30px 24px;
  text-align: center; transition: transform .15s, border-color .15s;
}
.lang-card:hover { transform: translateY(-3px); border-color: var(--pink); }
.lang-card img { width: 84px; height: 84px; border-radius: 28px; border: 3px solid #fff; box-shadow: 0 0 0 2px var(--pink); }
.lang-card b { display: block; font-size: 20px; color: var(--red-deep); margin-top: 12px; }
.lang-card span { font-size: 14px; color: var(--ink-soft); font-weight: 600; }
.lang-card .suggest {
  display: inline-block; margin-top: 10px; font-size: 12px; font-weight: 800;
  background: var(--red-light); color: var(--red-deep);
  border-radius: 999px; padding: 4px 12px;
}

/* ---------- 页脚 ---------- */
.site-footer {
  background: #fff; border-top: 2px solid var(--red-light);
  padding: 22px 0; margin-top: auto;
}
.site-footer .wrap {
  display: flex; align-items: center; justify-content: space-between;
  gap: 12px; flex-wrap: wrap; font-size: 13px; color: var(--ink-soft); font-weight: 600;
}
.site-footer a { color: var(--red-deep); text-decoration: none; font-weight: 800; margin-left: 14px; }
.site-footer a:hover { text-decoration: underline; }

@media (max-width: 640px) {
  .hero h1 { font-size: 27px; }
  .prose { padding: 20px 18px; }
  .site-nav a { padding: 7px 10px; font-size: 13px; }
}

@media (prefers-reduced-motion: reduce) {
  .btn, .lang-card, .site-nav a { transition: none !important; }
}