/* 基础与全局元素 */
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--text);
  background: var(--bg);
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}
button, input { font: inherit; color: inherit; }
button { cursor: pointer; }
a { color: inherit; text-decoration: none; }
::selection { color: var(--paper); background: var(--cinnabar-deep); }

main > section { scroll-margin-top: calc(var(--topbar-height) + 12px); }

/* 纸纹颗粒 */
.grain {
  position: fixed; inset: 0; z-index: 100;
  opacity: 0.05; pointer-events: none;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 160 160' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.82' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

/* 顶栏 */
.topbar {
  position: fixed; inset: 0 0 auto; z-index: 70;
  height: var(--topbar-height);
  padding: 0 var(--space-gutter);
  display: flex; align-items: center; gap: 40px;
  border-bottom: 1px solid var(--hairline);
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: blur(14px);
}
.logo {
  display: flex; align-items: center; gap: 12px;
  font: 700 24px/1 var(--font-display); letter-spacing: 0.1em;
}
.logo span {
  padding-left: 12px;
  border-left: 1px solid var(--hairline-strong);
  font: 9px/1.5 var(--font-mono); letter-spacing: 0.22em;
  color: var(--muted);
}
.topbar nav {
  margin-left: auto;
  display: flex; gap: 30px;
  font-size: 13px; letter-spacing: 0.06em;
}
.topbar nav a { position: relative; color: var(--muted); transition: color var(--duration); }
.topbar nav a::after {
  content: ""; position: absolute; left: 0; right: 100%; bottom: -6px;
  border-bottom: 1px solid var(--cinnabar);
  transition: right 0.25s var(--ease-out);
}
.topbar nav a:hover, .topbar nav a.active { color: var(--text); }
.topbar nav a.active::after { right: 0; }
/* 跨向词圃的入口：暖绿，暗示另一面 */
.topbar nav a.to-garden { color: #8cbf6a; }
.topbar nav a.to-garden:hover { color: #a6d685; }
.topbar nav a.to-garden::after { border-color: #8cbf6a; }

/* 按钮 */
.btn {
  padding: 10px 20px;
  border: 1px solid var(--hairline-strong);
  background: transparent;
  font: 12px var(--font-mono); letter-spacing: 0.14em;
  color: var(--text);
  transition: color var(--duration), background var(--duration), border-color var(--duration);
}
.btn:hover { color: var(--ink); background: var(--paper); border-color: var(--paper); }
.btn-dig { border-color: var(--cinnabar); color: var(--cinnabar); }
.btn-dig:hover { color: var(--paper); background: var(--cinnabar); border-color: var(--cinnabar); }

/* 印章 */
.seal {
  display: grid; place-items: center;
  width: 76px; aspect-ratio: 1;
  border-radius: 5px;
  color: #f3ece0; background: var(--cinnabar);
  font: 700 26px/1.15 var(--font-kai);
  letter-spacing: 0.08em;
  writing-mode: vertical-rl;
  box-shadow: 0 4px 24px rgba(207, 74, 43, 0.25);
  transform: rotate(-4deg);
}
.seal-sm { width: 58px; font-size: 13px; line-height: 1.3; writing-mode: horizontal-tb; text-align: center; }

/* 区块标题 */
.section { padding: var(--space-section) var(--space-gutter); }
.section-head {
  display: flex; flex-wrap: wrap; align-items: baseline; gap: 14px 36px;
  padding-bottom: 22px; margin-bottom: clamp(36px, 6vh, 64px);
  border-bottom: 1px solid var(--hairline-strong);
}
.section-no {
  font: 11px var(--font-mono); letter-spacing: 0.2em;
  color: var(--cinnabar);
}
.section-head h2 {
  margin: 0; width: 100%;
  font: 600 var(--text-h2)/1.05 var(--font-display);
  letter-spacing: 0.04em; color: var(--paper);
}
.section-head .head-note { max-width: 560px; margin: 0; color: var(--muted); font-size: 14px; }

/* 入场动画 */
[data-reveal] { opacity: 0; transform: translateY(26px); transition: opacity 0.7s ease, transform 0.7s var(--ease-out); }
[data-reveal].visible { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  [data-reveal] { opacity: 1; transform: none; transition: none; }
  * { animation-duration: 0.01ms !important; }
}