/* ══════════════════════════════════════════════════════════════════════════
   site.css — 共用：基础排版、导航、页脚、入场动效
   ══════════════════════════════════════════════════════════════════════════ */

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }

body {
  text-wrap: pretty;
  margin: 0;
  /* 纸张颗粒：极淡的分形噪点平铺在米白底上，给页面一层真实纸面的质感 */
  background: var(--paper) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='240' height='240'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.85' numOctaves='3' stitchTiles='stitch'/%3E%3CfeColorMatrix values='0 0 0 0 .42 0 0 0 0 .36 0 0 0 0 .27 0 0 0 .07 0'/%3E%3C/filter%3E%3Crect width='240' height='240' filter='url(%23n)'/%3E%3C/svg%3E");
  color: var(--ink);
  font-family: var(--font-body);
  font-size: var(--fs-body);
  line-height: 2;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
::selection { background: var(--accent-soft); }

.shell { position: relative; min-height: 100vh; overflow-x: clip; }

:focus-visible { outline: 1px solid var(--accent); outline-offset: 6px; }

.eyebrow {
  display: block;
  font-family: var(--font-label);
  font-size: var(--fs-label);
  letter-spacing: var(--ls-label);
  text-transform: uppercase;
  color: var(--accent);
}

/* ─────────────────────────────────────────────────────────── 导航 */
.nav {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 50;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  padding: 0 var(--edge);
  border-bottom: 1px solid transparent;
  transition: background var(--hover-dur) var(--ease-calm), border-color var(--hover-dur) var(--ease-calm);
}
.nav.is-scrolled {
  background: rgba(246, 243, 235, .76);
  backdrop-filter: saturate(1.1) blur(14px);
  -webkit-backdrop-filter: saturate(1.1) blur(14px);
  border-bottom-color: var(--line-soft);
}
.nav__brand {
  font-family: var(--font-title);
  font-size: 19px;
  font-weight: 600;
  letter-spacing: .16em;
  display: flex;
  align-items: center;
  gap: 9px;
}
.nav__brand-dot { width: 5px; height: 5px; border-radius: 50%; background: var(--accent); opacity: .85; }
.nav__links { margin: 0 0 0 auto; padding: 0; list-style: none; display: flex; gap: var(--s7); }
.nav__link {
  position: relative;
  font-size: var(--fs-nav);
  letter-spacing: .06em;
  color: var(--ink-muted);
  padding: 6px 1px;
  transition: color var(--hover-dur) var(--ease-calm);
}
.nav__link:hover, .nav__link.is-active { color: var(--ink); }
/* 下划线从左向右生长；离开时向右收起 */
.nav__link::after {
  content: '';
  position: absolute;
  left: 0; right: 0; bottom: -1px;
  height: 1px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: right;
  transition: transform .5s var(--ease-out);
}
.nav__link:hover::after, .nav__link.is-active::after { transform: scaleX(1); transform-origin: left; }
.nav__toggle {
  margin-left: auto;
  width: 40px; height: 40px;
  display: none;
  place-items: center;
  background: none; border: 0; padding: 0;
  cursor: pointer;
  color: var(--ink);
}
.nav__toggle span, .nav__toggle span::before, .nav__toggle span::after {
  display: block; width: 18px; height: 1px; background: currentColor; position: relative;
  transition: transform var(--hover-dur) var(--ease-calm);
}
.nav__toggle span::before, .nav__toggle span::after { content: ''; position: absolute; left: 0; }
.nav__toggle span::before { top: -6px; }
.nav__toggle span::after  { top: 6px; }
.nav[data-open='true'] .nav__toggle span { background: transparent; }
.nav[data-open='true'] .nav__toggle span::before { transform: translateY(6px) rotate(45deg); }
.nav[data-open='true'] .nav__toggle span::after  { transform: translateY(-6px) rotate(-45deg); }

/* ─────────────────────────────────────────────────────────── 页脚 */
.foot {
  max-width: calc(var(--maxw) + var(--gutter) * 2);
  margin: 0 auto;
  padding: var(--s7) var(--gutter);
  /* 三段式：左右等宽，备案号落在视觉正中 */
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: baseline;
  column-gap: var(--s5);
  font-size: var(--fs-foot);
  letter-spacing: .04em;
  color: var(--ink-faint);
}
.foot-wrap { border-top: 1px solid var(--line-soft); }
.foot__brand { font-family: var(--font-title); letter-spacing: .12em; color: var(--ink-muted); }
.foot__left { display: flex; align-items: baseline; gap: var(--s5); }
.foot__right { justify-self: end; }
.foot__icp {
  justify-self: center;
  color: var(--ink-muted);
  text-decoration: underline 1px transparent;
  text-underline-offset: 4px;
  transition: color var(--hover-dur) var(--ease-calm), text-decoration-color var(--hover-dur) var(--ease-calm);
}
.foot__icp:hover { color: var(--ink); text-decoration-color: currentColor; }

/* ─────────────────────────────────────────────────────────── 动效
   渐进增强：默认全部可见。CSS 入场动画自带 both 填充，无 JS 也会走完；
   只有 <html class="js"> 时，滚动淡入区块才进入隐藏初态。 */
@keyframes rise { from { opacity: 0; transform: translateY(14px); filter: blur(4px); } }
.rise { animation: rise 1.2s var(--ease-out) both; }

/* 逐字：由虚到实浮现 */
.ch {
  display: inline-block;
  animation: ch-in 1.3s var(--ease-out) calc(.12s + var(--i) * .1s) both;
}
@keyframes ch-in {
  from { opacity: 0; transform: translateY(.28em); filter: blur(12px); }
}

@keyframes draw { from { transform: scaleX(0); } }

/* 滚动出现：分隔线从左画出，子元素按 --d 依次上浮 */
.js .reveal::before { transform: scaleX(0); transition: transform 1.6s var(--ease-out); }
.js .reveal.is-in::before { transform: scaleX(1); }
.js .reveal .r {
  opacity: 0;
  transform: translateY(22px);
  transition: opacity 1.1s var(--ease-out) var(--d, 0s), transform 1.3s var(--ease-out) var(--d, 0s);
}
.js .reveal.is-in .r { opacity: 1; transform: none; }

/* ─────────────────────────────────────────────────────────── 响应式 */
@media (max-width: 1100px) {
  :root { --gutter: 64px; }
}

@media (max-width: 720px) {
  :root { --gutter: 24px; --nav-h: 64px; --s9: 64px; --s10: 88px; --s11: 112px; }

  .nav__toggle { display: grid; }
  .nav__links {
    position: fixed;
    inset: var(--nav-h) 0 auto 0;
    flex-direction: column;
    gap: 0;
    padding: var(--s3) var(--gutter) var(--s5);
    background: rgba(246, 243, 235, .97);
    border-bottom: 1px solid var(--line-soft);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-6px);
    transition: opacity .3s var(--ease-calm), transform .3s var(--ease-calm), visibility .3s;
  }
  .nav[data-open='true'] .nav__links { opacity: 1; visibility: visible; transform: none; }
  .nav__link { display: block; padding: 14px 0; font-size: 15px; border-bottom: 1px solid var(--line-soft); }
  .nav__links li:last-child .nav__link { border-bottom: 0; }
  .nav__link::after { right: auto; width: 22px; bottom: 10px; }

  .foot { display: flex; flex-direction: column; gap: var(--s2); padding: var(--s6) var(--gutter); }
  .foot__left { display: contents; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .js .reveal::before, .js .reveal .r { opacity: 1; transform: none; }
}