/* ============================================================
   yu's blog — stylesheet
   暖白纸感 + 衬线标题 + 一个陶土色强调色。没有外部字体请求。
   ============================================================ */

:root {
  --bg: #fbf9f6;
  --surface: #ffffff;
  --surface-2: #f5f1ea;
  --ink: #1b1917;
  --ink-2: #5f5952;
  --ink-3: #948c82;
  --line: #e7e1d7;
  --line-strong: #d6cec1;
  --accent: #b0472b;
  --accent-soft: #f4e7e0;
  --shadow: 0 1px 2px rgba(27, 25, 23, 0.04), 0 8px 24px -12px rgba(27, 25, 23, 0.14);

  --serif: "Iowan Old Style", "Source Serif 4", "Songti SC", "Noto Serif CJK SC",
    "Noto Serif SC", Palatino, Georgia, "STSong", serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --mono: ui-monospace, "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;

  --measure: 44rem;
  --wrap: 46rem;
}

html[data-theme="dark"] {
  --bg: #131211;
  --surface: #1b1a18;
  --surface-2: #222020;
  --ink: #eeebe4;
  --ink-2: #a8a29a;
  --ink-3: #7b756d;
  --line: #2b2825;
  --line-strong: #3a3632;
  --accent: #e2855f;
  --accent-soft: #2c211c;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 12px 28px -16px rgba(0, 0, 0, 0.6);
}

/* ---------- reset ---------- */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  transition: background-color 0.35s ease, color 0.35s ease;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1 0 auto;
}

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

a {
  color: inherit;
}

::selection {
  background: var(--accent-soft);
  color: var(--ink);
}

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

.wrap {
  width: 100%;
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 0 26px;
}

.skip {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--ink);
  color: var(--bg);
  padding: 8px 14px;
  z-index: 999;
  border-radius: 0 0 8px 0;
  font-size: 13px;
}

.skip:focus {
  left: 0;
}

/* ---------- header ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: var(--bg);
  background: color-mix(in srgb, var(--bg) 84%, transparent);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  height: 58px;
}

.brand {
  font-family: var(--serif);
  font-size: 1.0625rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  text-decoration: none;
  color: var(--ink);
  transition: color 0.2s ease;
  white-space: nowrap;
}

.brand:hover {
  color: var(--accent);
}

.nav {
  display: flex;
  align-items: center;
  gap: 20px;
  font-size: 0.8125rem;
}

.nav a {
  position: relative;
  text-decoration: none;
  color: var(--ink-2);
  transition: color 0.18s ease;
}

.nav a:hover {
  color: var(--ink);
}

.nav a.is-active {
  color: var(--ink);
}

.nav a.is-active::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -4px;
  height: 1.5px;
  background: var(--accent);
  border-radius: 2px;
}

.nav-rss {
  font-family: var(--mono);
  font-size: 0.6875rem;
  letter-spacing: 0.08em;
  color: var(--ink-3) !important;
}

.theme-toggle {
  display: grid;
  place-items: center;
  width: 30px;
  height: 30px;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: 50%;
  background: transparent;
  color: var(--ink-2);
  cursor: pointer;
  transition: color 0.2s ease, border-color 0.2s ease, transform 0.25s ease;
}

.theme-toggle:hover {
  color: var(--accent);
  border-color: var(--line-strong);
  transform: rotate(-12deg);
}

html[data-theme="dark"] .icon-sun {
  display: none;
}

html:not([data-theme="dark"]) .icon-moon {
  display: none;
}

/* ---------- home hero ---------- */

.hero {
  padding-top: clamp(56px, 9vw, 92px);
  padding-bottom: clamp(38px, 5vw, 56px);
}

.eyebrow {
  margin: 0 0 22px;
  font-family: var(--mono);
  font-size: 0.6875rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--ink-3);
}

.hero h1 {
  margin: 0 0 24px;
  font-family: var(--serif);
  font-size: clamp(2.1rem, 6.2vw, 3.3rem);
  font-weight: 600;
  line-height: 1.16;
  letter-spacing: -0.03em;
}

.hero-text {
  margin: 0;
  max-width: 32em;
  color: var(--ink-2);
  font-size: 1.0625rem;
  line-height: 1.85;
}

/* ---------- section label ---------- */

.section-label {
  display: flex;
  align-items: center;
  gap: 14px;
  margin: 0 0 2px;
  font-family: var(--mono);
  font-size: 0.6875rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-3);
}

.section-label span {
  white-space: nowrap;
}

.section-label::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--line);
}

/* ---------- post list ---------- */

.post-list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-bottom: 1px solid var(--line);
}

.post-item {
  border-top: 1px solid var(--line);
}

.post-item > a {
  display: grid;
  grid-template-columns: 88px 1fr;
  gap: 26px;
  padding: 26px 4px 26px 0;
  text-decoration: none;
  transition: padding-left 0.28s cubic-bezier(0.2, 0.7, 0.3, 1);
}

.post-item > a:hover {
  padding-left: 8px;
}

.post-date {
  font-family: var(--mono);
  font-size: 0.6875rem;
  letter-spacing: 0.04em;
  color: var(--ink-3);
  padding-top: 6px;
  white-space: nowrap;
}

.post-title {
  margin: 0 0 7px;
  font-family: var(--serif);
  font-size: 1.1875rem;
  font-weight: 600;
  line-height: 1.5;
  letter-spacing: -0.012em;
  transition: color 0.2s ease;
}

.post-item > a:hover .post-title {
  color: var(--accent);
}

.post-excerpt {
  margin: 0;
  color: var(--ink-2);
  font-size: 0.9063rem;
  line-height: 1.7;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.post-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  margin-top: 12px;
}

.tag {
  font-family: var(--mono);
  font-size: 0.625rem;
  letter-spacing: 0.06em;
  color: var(--ink-3);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 2px 9px 1px;
  text-decoration: none;
  transition: color 0.2s ease, border-color 0.2s ease;
}

.tag-link:hover {
  color: var(--accent);
  border-color: var(--accent);
}

.feed-note {
  margin: 22px 0 0;
  font-family: var(--mono);
  font-size: 0.6875rem;
  letter-spacing: 0.05em;
  color: var(--ink-3);
}

.feed-note a {
  color: var(--ink-2);
  text-decoration: none;
  border-bottom: 1px solid var(--line-strong);
  padding-bottom: 1px;
}

.feed-note a:hover {
  color: var(--accent);
  border-color: var(--accent);
}

.post-list--flush {
  border-bottom: 0;
}

/* ---------- article ---------- */

.progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 2px;
  width: 0;
  background: var(--accent);
  z-index: 60;
  transition: width 0.08s linear;
  border-radius: 0 2px 2px 0;
}

.post-head {
  padding: clamp(40px, 7vw, 68px) 0 28px;
  border-bottom: 1px solid var(--line);
  margin-bottom: 42px;
}

.back {
  display: inline-block;
  font-family: var(--mono);
  font-size: 0.6875rem;
  letter-spacing: 0.08em;
  color: var(--ink-3);
  text-decoration: none;
  margin-bottom: 22px;
  transition: color 0.2s ease, transform 0.2s ease;
}

.back:hover {
  color: var(--accent);
}

.post-head h1 {
  margin: 0 0 18px;
  font-family: var(--serif);
  font-size: clamp(1.75rem, 4.6vw, 2.4rem);
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: -0.022em;
}

.post-meta-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 9px;
  font-family: var(--mono);
  font-size: 0.6875rem;
  letter-spacing: 0.04em;
  color: var(--ink-3);
}

.post-meta-row .dot {
  color: var(--line-strong);
}

.post-head-note {
  margin: 10px 0 0;
  font-family: var(--mono);
  font-size: 0.6875rem;
  color: var(--ink-3);
}

/* ---------- prose ---------- */

.prose {
  max-width: var(--measure);
  font-size: 1.0313rem;
  line-height: 1.95;
}

.prose > *:first-child {
  margin-top: 0;
}

.prose p {
  margin: 0 0 1.45em;
}

.prose h2 {
  margin: 2.6em 0 0.85em;
  font-family: var(--serif);
  font-size: 1.4375rem;
  font-weight: 600;
  line-height: 1.45;
  letter-spacing: -0.015em;
  scroll-margin-top: 84px;
}

.prose h3 {
  margin: 2.1em 0 0.7em;
  font-size: 1.0938rem;
  font-weight: 600;
  letter-spacing: -0.005em;
  scroll-margin-top: 84px;
}

.prose h2 + p,
.prose h3 + p {
  margin-top: 0;
}

.prose ul,
.prose ol {
  margin: 0 0 1.45em;
  padding-left: 1.3em;
}

.prose li {
  margin: 0.4em 0;
  padding-left: 0.15em;
}

.prose li::marker {
  color: var(--ink-3);
  font-size: 0.9em;
}

.prose strong {
  font-weight: 600;
  color: var(--ink);
}

.prose em {
  font-style: normal;
  color: var(--accent);
}

.prose a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid color-mix(in srgb, var(--accent) 38%, transparent);
  transition: border-color 0.2s ease, background-color 0.2s ease;
}

.prose a:hover {
  border-bottom-color: var(--accent);
  background: var(--accent-soft);
}

.prose code {
  font-family: var(--mono);
  font-size: 0.855em;
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: 5px;
  padding: 0.12em 0.38em;
  word-break: break-word;
}

.prose pre {
  position: relative;
  margin: 0 0 1.7em;
  padding: 20px 22px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  overflow-x: auto;
  font-size: 0.8438rem;
  line-height: 1.75;
  box-shadow: var(--shadow);
  tab-size: 2;
}

.prose pre code {
  padding: 0;
  border: 0;
  background: none;
  font-size: inherit;
  color: var(--ink);
}

.prose pre[data-lang]::before {
  content: attr(data-lang);
  position: absolute;
  top: 9px;
  right: 14px;
  font-family: var(--mono);
  font-size: 0.625rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-3);
  opacity: 0.75;
  pointer-events: none;
}

.prose blockquote {
  margin: 0 0 1.7em;
  padding: 2px 0 2px 20px;
  border-left: 2px solid var(--accent);
  color: var(--ink-2);
}

.prose blockquote p:last-child {
  margin-bottom: 0;
}

.prose hr {
  margin: 2.8em 0;
  border: 0;
  height: 1px;
  background: var(--line);
}

.prose img {
  margin: 1.9em 0;
  border-radius: 10px;
  box-shadow: var(--shadow);
}

.prose del {
  color: var(--ink-3);
}

/* ---------- post nav ---------- */

.post-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin: 64px 0 0;
  padding-top: 28px;
  border-top: 1px solid var(--line);
}

.post-nav-item {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 14px 16px;
  text-decoration: none;
  border: 1px solid var(--line);
  border-radius: 10px;
  transition: border-color 0.2s ease, background-color 0.2s ease, transform 0.2s ease;
}

.post-nav-item:hover {
  border-color: var(--line-strong);
  background: var(--surface);
  transform: translateY(-1px);
}

.post-nav-item--end {
  text-align: right;
  align-items: flex-end;
}

.post-nav-label {
  font-family: var(--mono);
  font-size: 0.625rem;
  letter-spacing: 0.1em;
  color: var(--ink-3);
}

.post-nav-title {
  font-family: var(--serif);
  font-size: 0.9063rem;
  line-height: 1.5;
  color: var(--ink);
}

/* ---------- tags ---------- */

.tag-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.tag-pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 15px;
  border: 1px solid var(--line);
  border-radius: 999px;
  text-decoration: none;
  font-size: 0.875rem;
  color: var(--ink-2);
  transition: color 0.2s ease, border-color 0.2s ease, background-color 0.2s ease;
}

.tag-pill:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: var(--accent-soft);
}

.tag-count {
  font-family: var(--mono);
  font-size: 0.6875rem;
  color: var(--ink-3);
}

/* ---------- 404 ---------- */

.not-found {
  padding-top: clamp(72px, 14vw, 140px);
  padding-bottom: clamp(72px, 14vw, 140px);
}

.not-found h1 {
  margin: 0 0 20px;
  font-family: var(--serif);
  font-size: clamp(1.75rem, 5vw, 2.4rem);
  font-weight: 600;
  letter-spacing: -0.02em;
}

.not-found p {
  color: var(--ink-2);
  margin: 0 0 14px;
}

/* ---------- footer ---------- */

.site-footer {
  flex-shrink: 0;
  margin-top: clamp(64px, 10vw, 104px);
  border-top: 1px solid var(--line);
  padding: 26px 0 40px;
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 10px;
  font-family: var(--mono);
  font-size: 0.6875rem;
  letter-spacing: 0.04em;
  color: var(--ink-3);
}

.footer-inner a {
  color: var(--ink-2);
  text-decoration: none;
  border-bottom: 1px solid var(--line-strong);
}

.footer-inner a:hover {
  color: var(--accent);
  border-color: var(--accent);
}

/* ---------- motion ---------- */

@media (prefers-reduced-motion: no-preference) {
  .fade {
    animation: fade-up 0.65s cubic-bezier(0.2, 0.7, 0.3, 1) both;
  }

  @keyframes fade-up {
    from {
      opacity: 0;
      transform: translateY(10px);
    }
    to {
      opacity: 1;
      transform: none;
    }
  }
}

/* ---------- responsive ---------- */

@media (max-width: 620px) {
  .wrap {
    padding-left: 20px;
    padding-right: 20px;
  }

  .nav {
    gap: 15px;
  }

  .nav-rss {
    display: none;
  }

  .post-item > a {
    grid-template-columns: 1fr;
    gap: 6px;
    padding: 22px 0;
  }

  .post-item > a:hover {
    padding-left: 0;
  }

  .post-date {
    padding-top: 0;
    order: -1;
  }

  .post-nav {
    grid-template-columns: 1fr;
  }

  .post-nav-item--end {
    text-align: left;
    align-items: flex-start;
  }

  .prose {
    font-size: 1rem;
    line-height: 1.9;
  }

  .prose pre {
    margin-left: -20px;
    margin-right: -20px;
    border-radius: 0;
    border-left: 0;
    border-right: 0;
  }
}