/* 道德经官网 — 墨韵禅意 */
:root {
  --ink: #1a1c1a;
  --ink-soft: #2e322e;
  --mist: #8a9188;
  --paper: #f3f5f1;
  --paper-deep: #e6ebe3;
  --jade: #3d6b5a;
  --jade-deep: #2a4f42;
  --line: rgba(26, 28, 26, 0.12);
  --shadow: rgba(26, 28, 26, 0.06);
  --serif: "Source Han Serif SC", "Noto Serif SC", "Songti SC", "STSong", "SimSun", "Times New Roman", serif;
  --sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --display: "STKaiti", "KaiTi", "Kaiti SC", "DFKai-SB", var(--serif);
  --max: 1080px;
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

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

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--ink);
  font-family: var(--serif);
  font-size: 17px;
  line-height: 1.85;
  background:
    radial-gradient(1200px 600px at 10% -10%, rgba(61, 107, 90, 0.08), transparent 55%),
    radial-gradient(900px 500px at 100% 0%, rgba(26, 28, 26, 0.05), transparent 50%),
    linear-gradient(180deg, #f7f8f5 0%, var(--paper) 40%, var(--paper-deep) 100%);
  min-height: 100vh;
  overflow-x: hidden;
}

.mist {
  pointer-events: none;
  position: fixed;
  inset: 0;
  background:
    repeating-linear-gradient(
      0deg,
      transparent,
      transparent 3px,
      rgba(26, 28, 26, 0.012) 3px,
      rgba(26, 28, 26, 0.012) 4px
    );
  opacity: 0.55;
  z-index: 0;
}

.wrap {
  width: min(100% - 2.5rem, var(--max));
  margin-inline: auto;
  position: relative;
  z-index: 1;
}

a {
  color: var(--jade-deep);
  text-decoration: none;
  transition: color .25s var(--ease);
}
a:hover { color: var(--jade); }

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

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(14px);
  background: rgba(243, 245, 241, 0.82);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  min-height: 72px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  color: inherit;
}

.brand-mark {
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border: 1px solid var(--ink);
  border-radius: 50%;
  font-family: var(--display);
  font-size: 1.35rem;
  line-height: 1;
  background: rgba(255, 255, 255, 0.35);
}

.brand-text {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
}
.brand-text strong {
  font-family: var(--display);
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: 0.12em;
}
.brand-text em {
  font-style: normal;
  font-family: var(--sans);
  font-size: 0.75rem;
  color: var(--mist);
  letter-spacing: 0.08em;
}

.site-nav {
  display: flex;
  gap: 1.5rem;
  align-items: center;
}
.site-nav a {
  font-family: var(--sans);
  font-size: 0.92rem;
  color: var(--ink-soft);
  letter-spacing: 0.08em;
  position: relative;
}
.site-nav a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -4px;
  width: 0;
  height: 1px;
  background: var(--jade);
  transition: width .35s var(--ease);
}
.site-nav a:hover::after { width: 100%; }

.nav-toggle {
  display: none;
  width: 42px;
  height: 42px;
  border: 1px solid var(--line);
  background: transparent;
  border-radius: 999px;
  cursor: pointer;
  position: relative;
}
.nav-toggle span {
  position: absolute;
  left: 12px;
  right: 12px;
  height: 1px;
  background: var(--ink);
  transition: .3s var(--ease);
}
.nav-toggle span:first-child { top: 17px; }
.nav-toggle span:last-child { top: 24px; }
.nav-toggle[aria-expanded="true"] span:first-child { top: 20px; transform: rotate(35deg); }
.nav-toggle[aria-expanded="true"] span:last-child { top: 20px; transform: rotate(-35deg); }

/* Hero */
.hero {
  position: relative;
  min-height: min(88vh, 820px);
  display: grid;
  align-items: center;
  overflow: hidden;
  isolation: isolate;
}

.hero-inner {
  padding: 5rem 0 4rem;
  text-align: center;
  animation: rise 1.1s var(--ease) both;
}

.hero-kicker {
  font-family: var(--sans);
  font-size: 0.8rem;
  letter-spacing: 0.35em;
  color: var(--mist);
  margin: 0 0 1.25rem;
  text-transform: none;
}

.hero-title {
  margin: 0;
  font-family: var(--display);
  font-weight: 500;
  font-size: clamp(2.6rem, 8vw, 5.2rem);
  letter-spacing: 0.28em;
  line-height: 1.15;
  text-indent: 0.28em;
}

.hero-desc {
  margin: 1.5rem auto 0;
  max-width: 28rem;
  color: var(--ink-soft);
  font-size: 1.05rem;
  letter-spacing: 0.12em;
}

.hero-cta {
  margin-top: 2.5rem;
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.hero-ink {
  position: absolute;
  inset: auto -10% -30% -10%;
  height: 55%;
  background:
    radial-gradient(ellipse at 50% 0%, rgba(42, 79, 66, 0.18), transparent 60%),
    radial-gradient(ellipse at 20% 40%, rgba(26, 28, 26, 0.08), transparent 45%),
    radial-gradient(ellipse at 80% 50%, rgba(26, 28, 26, 0.06), transparent 40%);
  z-index: -1;
  animation: drift 14s ease-in-out infinite alternate;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0 1.4rem;
  border-radius: 999px;
  font-family: var(--sans);
  font-size: 0.92rem;
  letter-spacing: 0.12em;
  border: 1px solid transparent;
  transition: transform .25s var(--ease), background .25s, color .25s, border-color .25s;
}
.btn:hover { transform: translateY(-1px); }
.btn-primary {
  background: var(--ink);
  color: var(--paper);
}
.btn-primary:hover { background: var(--jade-deep); color: #fff; }
.btn-ghost {
  border-color: var(--ink);
  color: var(--ink);
  background: transparent;
}
.btn-ghost:hover { background: rgba(26, 28, 26, 0.04); color: var(--ink); }

/* Sections */
.section { padding: 4.5rem 0 5rem; }
.section-head {
  text-align: center;
  margin-bottom: 2.5rem;
}
.section-head h1,
.section-head h2 {
  margin: 0;
  font-family: var(--display);
  font-weight: 500;
  font-size: clamp(1.8rem, 4vw, 2.4rem);
  letter-spacing: 0.2em;
}
.section-head p {
  margin: 0.75rem 0 0;
  color: var(--mist);
  font-family: var(--sans);
  font-size: 0.9rem;
  letter-spacing: 0.15em;
}

.article-list {
  display: grid;
  gap: 0;
  border-top: 1px solid var(--line);
}

.article-row {
  border-bottom: 1px solid var(--line);
  animation: rise .8s var(--ease) both;
  animation-delay: calc(var(--i, 0) * 0.05s);
}

.article-link {
  display: grid;
  grid-template-columns: 7rem 1fr;
  gap: 1rem 1.5rem;
  padding: 1.6rem 0.25rem;
  color: inherit;
}
.article-link time {
  font-family: var(--sans);
  font-size: 0.82rem;
  color: var(--mist);
  letter-spacing: 0.06em;
  padding-top: 0.35rem;
}
.article-link h3 {
  margin: 0;
  font-family: var(--display);
  font-size: 1.35rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  grid-column: 2;
}
.article-link p {
  margin: 0.35rem 0 0;
  grid-column: 2;
  color: var(--mist);
  font-size: 0.95rem;
  line-height: 1.7;
}
.article-link:hover h3 { color: var(--jade-deep); }

.pager {
  display: flex;
  justify-content: center;
  gap: 0.5rem;
  margin-top: 2.5rem;
}
.pager a {
  width: 40px;
  height: 40px;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 50%;
  font-family: var(--sans);
  color: var(--ink-soft);
}
.pager a.is-active,
.pager a:hover {
  background: var(--ink);
  color: var(--paper);
  border-color: var(--ink);
}

/* Post */
.post {
  padding: 3.5rem 0 5rem;
  max-width: 760px;
}
.post-head { margin-bottom: 2.5rem; text-align: center; }
.post-meta {
  display: flex;
  justify-content: center;
  gap: 1.25rem;
  font-family: var(--sans);
  font-size: 0.82rem;
  color: var(--mist);
  letter-spacing: 0.08em;
  margin: 0 0 1rem;
}
.post-head h1 {
  margin: 0;
  font-family: var(--display);
  font-weight: 500;
  font-size: clamp(1.8rem, 4.5vw, 2.6rem);
  letter-spacing: 0.12em;
  line-height: 1.35;
}

.prose {
  font-size: 1.05rem;
  line-height: 2;
  color: var(--ink-soft);
}
.prose p { margin: 0 0 1.25em; text-align: justify; }
.prose h2, .prose h3 {
  font-family: var(--display);
  font-weight: 500;
  color: var(--ink);
  letter-spacing: 0.08em;
  margin: 2em 0 0.8em;
}
.prose blockquote {
  margin: 1.5em 0;
  padding: 0.5em 0 0.5em 1.25em;
  border-left: 2px solid var(--jade);
  color: var(--ink);
  font-family: var(--display);
}
.prose img {
  display: block;
  margin: 1.5em auto;
}
.prose iframe {
  max-width: 100%;
  display: block;
  margin: 1.5em auto;
}

.post-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--line);
}
.post-nav a {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  padding: 1rem;
  border: 1px solid var(--line);
  color: inherit;
  background: rgba(255, 255, 255, 0.35);
}
.post-nav a span {
  font-family: var(--sans);
  font-size: 0.75rem;
  color: var(--mist);
  letter-spacing: 0.1em;
}
.post-nav a strong {
  font-weight: 500;
  font-family: var(--display);
  letter-spacing: 0.05em;
}
.post-nav .next { text-align: right; }

.related {
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--line);
}
.related h2 {
  margin: 0 0 1rem;
  font-family: var(--display);
  font-weight: 500;
  font-size: 1.2rem;
  letter-spacing: 0.15em;
}
.related ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.65rem;
}
.related a {
  font-family: var(--serif);
  color: var(--ink-soft);
}
.related a:hover { color: var(--jade-deep); }

.error-page { text-align: center; padding: 8rem 0; }
.error-code {
  font-family: var(--display);
  font-size: 5rem;
  margin: 0;
  letter-spacing: 0.2em;
  color: var(--jade);
}
.error-page h1 {
  font-family: var(--display);
  font-weight: 500;
  letter-spacing: 0.2em;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--line);
  padding: 2.5rem 0 3rem;
  text-align: center;
}
.footer-quote {
  margin: 0;
  font-family: var(--display);
  letter-spacing: 0.18em;
  color: var(--ink-soft);
}
.footer-meta {
  margin: 0.85rem 0 0;
  font-family: var(--sans);
  font-size: 0.78rem;
  color: var(--mist);
  letter-spacing: 0.06em;
}
.footer-meta a { color: var(--mist); }

@keyframes rise {
  from { opacity: 0; transform: translateY(18px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes drift {
  from { transform: translateY(0) scale(1); }
  to { transform: translateY(-18px) scale(1.04); }
}

@media (max-width: 768px) {
  .nav-toggle { display: inline-block; }
  .site-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    display: none;
    flex-direction: column;
    gap: 0;
    background: rgba(243, 245, 241, 0.98);
    border-bottom: 1px solid var(--line);
    padding: 0.5rem 1.25rem 1rem;
  }
  .site-nav.is-open { display: flex; }
  .site-nav a {
    width: 100%;
    padding: 0.85rem 0;
    border-bottom: 1px solid var(--line);
  }
  .header-inner { position: relative; }
  .article-link {
    grid-template-columns: 1fr;
    gap: 0.35rem;
  }
  .article-link time,
  .article-link h3,
  .article-link p { grid-column: 1; }
  .post-nav { grid-template-columns: 1fr; }
  .hero-title { letter-spacing: 0.16em; text-indent: 0.16em; }
  .brand-text em { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation: none !important;
    transition: none !important;
  }
}