/* ========================================
   Diff's Blog — Swiss minimal, sidebar-nav
   ======================================== */

:root {
  --accent: #FF7F83;
  --bg: #FCFCFB;
  --fg: #000000;
  --fg-soft: #1A1A1A;
  --fg-mute: #4E4E48;
  --rule: #EAEAE6;

  --ff-sans: "Inter", "Noto Sans SC", -apple-system, BlinkMacSystemFont, sans-serif;
  --ff-zh: "Noto Sans SC", "Inter", -apple-system, BlinkMacSystemFont, sans-serif;
  --ff-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;

  --fs-xs: 12px;
  --fs-s: 13px;
  --fs-b: 15px;
  --fs-m: 16px;
  --fs-l: 19px;
  --fs-xl: 24px;
  --fs-xxl: 34px;

  --lh-body: 1.7;
  --easing: cubic-bezier(.22,.61,.36,1);

  --sidebar-w: 220px;
  --content-w: 640px;
  --gutter: 64px;
  --side: 48px;
}

[data-dark="true"] {
  --bg: #121211;
  --fg: #FFFFFF;
  --fg-soft: #EDEDE6;
  --fg-mute: #AEAEA6;
  --rule: #262624;
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html, body {
  margin: 0; padding: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--ff-zh);
  font-size: var(--fs-b);
  line-height: var(--lh-body);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
::selection { background: var(--accent); color: #fff; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; padding: 0; }
h1, h2, h3, h4, h5, h6 { margin: 0; font-weight: 500; letter-spacing: -0.01em; }

/* ---------- App shell ---------- */
.shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr) var(--sidebar-w);
  gap: var(--gutter);
  max-width: 1080px;
  margin: 0 auto;
  padding: 64px var(--side) 0;
  align-items: start;
}

/* ---------- Sidebar ---------- */
.sidebar {
  position: sticky;
  top: 64px;
  height: calc(100vh - 96px);
  display: flex;
  flex-direction: column;
  gap: 48px;
  align-items: flex-end;
  text-align: right;
}

.brand { display: block; }
.brand .logo { width: 32px; height: 32px; display: block; }

.side-nav { display: flex; flex-direction: column; gap: 10px; align-items: flex-end; }
.side-nav a {
  display: inline-flex;
  align-items: center;
  padding: 2px 0;
  font-size: var(--fs-b);
  color: var(--fg-mute);
  transition: color .15s var(--easing);
  position: relative;
}
.side-nav a:hover { color: var(--fg); }
.side-nav a.is-active { color: var(--accent); }
.side-nav a.is-active::after {
  content: "";
  position: absolute;
  left: 100%;
  top: 50%;
  transform: translateY(-50%);
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
  margin-left: 10px;
}

.side-util {
  margin-top: auto;
  padding-top: 40px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  align-items: flex-end;
}
.side-util .icon-btn {
  background: none;
  border: 0;
  padding: 4px;
  cursor: pointer;
  color: var(--fg-mute);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: color .15s var(--easing);
}
.side-util .icon-btn:hover { color: var(--fg); }
.side-util .icon-btn svg { display: block; }

/* ---------- Content column ---------- */
.content {
  max-width: var(--content-w);
  padding-bottom: 120px;
}

.content-foot {
  margin-top: 120px;
  padding-top: 24px;
  font-family: var(--ff-mono);
  font-size: var(--fs-xs);
  color: var(--fg-mute);
}

/* ---------- Typography helpers ---------- */
.h1 { font-size: var(--fs-xxl); line-height: 1.2; letter-spacing: -0.02em; font-weight: 500; }
.h2 { font-size: var(--fs-xl); line-height: 1.3; font-weight: 500; }
.h3 { font-size: var(--fs-l); line-height: 1.35; font-weight: 500; }
.lede { font-size: var(--fs-m); color: var(--fg-soft); line-height: 1.65; margin: 0 0 18px; }
.lede:last-child { margin-bottom: 0; }
.mono { font-family: var(--ff-mono); }
.mute { color: var(--fg-mute); }

.block { padding: 0 0 48px; }
.block-tight { padding: 24px 0; }

/* ---------- Prose (for page content) ---------- */
.prose p { margin: 0 0 18px; color: var(--fg); font-size: var(--fs-m); line-height: 1.8; }
.prose p:last-child { margin: 0; }
.prose h2 { margin: 32px 0 12px; font-size: var(--fs-xl); font-weight: 500; }
.prose h3 { margin: 32px 0 12px; font-size: var(--fs-l); font-weight: 500; }
.prose h4 { margin: 24px 0 8px; font-size: var(--fs-m); font-weight: 500; }

.prose ul, .prose ol {
  margin: 0 0 18px;
  padding-left: 1.25rem;
  font-size: var(--fs-m);
  line-height: 1.8;
  color: var(--fg-soft);
}
.prose li { margin-bottom: 4px; }
.prose li::marker { color: var(--fg-mute); }

.prose blockquote {
  margin: 24px 0;
  padding: 0 0 0 18px;
  border-left: 2px solid var(--accent);
  color: var(--fg-soft);
  font-size: var(--fs-m);
}
.prose blockquote p { color: var(--fg-soft); }

.prose img {
  width: 100%;
  height: auto;
  margin: 24px 0;
  border: 1px solid var(--rule);
}

.prose code {
  margin: 0 2px;
  padding: 2px 5px;
  border: 1px solid var(--rule);
  background: var(--bg);
  font-family: var(--ff-mono);
  font-size: 0.9em;
}
[data-dark="true"] .prose code { background: #1a1a19; }

.prose pre {
  margin: 24px 0;
  padding: 16px;
  overflow-x: auto;
  border: 1px solid var(--rule);
  background: var(--bg);
}
[data-dark="true"] .prose pre { background: #1a1a19; }

.prose pre code {
  margin: 0;
  padding: 0;
  border: 0;
  background: transparent;
}

.prose hr {
  width: 33%;
  margin: 48px auto;
  border: 0;
  border-top: 1px solid var(--rule);
}

.prose a {
  color: var(--accent);
  border-bottom: 1px solid transparent;
  transition: border-color .15s var(--easing);
}
.prose a:hover { border-bottom-color: var(--accent); }

/* ---------- Inline link ---------- */
.inline-link {
  color: var(--accent);
  border-bottom: 1px solid transparent;
  transition: border-color .15s var(--easing);
}
.inline-link:hover { border-bottom-color: var(--accent); }

/* ---------- Section header ---------- */
.sect-hd {
  padding: 12px 0;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
}
.sect-hd .title {
  font-size: var(--fs-s);
  color: var(--fg-mute);
  font-family: var(--ff-mono);
  letter-spacing: 0.02em;
}
.sect-hd a {
  font-size: var(--fs-s);
  color: var(--fg-mute);
  transition: color .15s var(--easing);
}
.sect-hd a:hover { color: var(--fg); }

/* ---------- Post list ---------- */
.post-row {
  display: grid;
  grid-template-columns: 70px 1fr;
  gap: 16px;
  align-items: baseline;
  padding: 10px 0;
  transition: color .15s var(--easing);
}
.post-row .date {
  font-size: var(--fs-xs);
  color: var(--fg-mute);
  font-family: var(--ff-mono);
  letter-spacing: 0.02em;
  font-variant-numeric: tabular-nums;
}
.post-row .title {
  font-size: var(--fs-m);
  color: var(--fg);
}
a.post-row:hover .title { color: var(--accent); }

/* ---------- Year heading ---------- */
.year-head {
  display: grid;
  grid-template-columns: 70px 1fr;
  gap: 16px;
  padding: 28px 0 10px;
  align-items: baseline;
}
.year-head .y {
  font-size: var(--fs-xs);
  color: var(--fg-mute);
  font-family: var(--ff-mono);
  letter-spacing: 0.02em;
}
.year-head .count {
  font-size: var(--fs-xs);
  color: var(--fg-mute);
}

/* ---------- Article ---------- */
.article { padding: 16px 0 24px; }

.article-header { margin-bottom: 36px; }
.article-header .meta {
  font-family: var(--ff-mono);
  font-size: var(--fs-xs);
  color: var(--fg-mute);
  margin-bottom: 14px;
  letter-spacing: 0.02em;
  display: flex;
  gap: 14px;
}
.article-header h1 {
  font-size: var(--fs-xxl);
  line-height: 1.25;
  letter-spacing: -0.015em;
  font-weight: 500;
  margin: 0 0 14px;
}

.article-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 48px;
  padding-top: 20px;
  border-top: 1px solid var(--rule);
  font-size: var(--fs-s);
}
.article-nav a {
  display: block;
  color: var(--fg-mute);
  transition: color .15s var(--easing);
}
.article-nav a:hover { color: var(--fg); }
.article-nav .right { text-align: right; }
.article-nav .lbl {
  font-family: var(--ff-mono);
  font-size: var(--fs-xs);
  margin-bottom: 6px;
  letter-spacing: 0.02em;
}
.article-nav .ttl { color: var(--fg); font-size: var(--fs-m); }

.back {
  padding: 0 0 18px;
  font-size: var(--fs-s);
  color: var(--fg-mute);
  transition: color .15s var(--easing);
  display: inline-block;
}
.back:hover { color: var(--fg); }

/* ---------- Tags ---------- */
.post-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 24px;
  padding-top: 20px;
  border-top: 1px solid var(--rule);
}
.tag {
  font-family: var(--ff-mono);
  font-size: var(--fs-xs);
  color: var(--fg-mute);
  letter-spacing: 0.02em;
}

/* ---------- Page intro ---------- */
.page-intro { margin-bottom: 8px; }
.page-intro .sub {
  font-size: var(--fs-s);
  color: var(--fg-mute);
  margin-top: 8px;
  font-family: var(--ff-mono);
}

/* ---------- Fade in ---------- */
.fade-in { animation: fade-in .4s var(--easing) both; }
@keyframes fade-in {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: none; }
}

/* ---------- Mobile ---------- */
@media (max-width: 820px) {
  :root { --side: 24px; }

  .shell {
    grid-template-columns: 1fr;
    gap: 28px;
    padding: 28px var(--side) 0;
  }

  .sidebar {
    position: static;
    height: auto;
    flex-direction: row;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    border-bottom: 1px solid var(--rule);
    padding-bottom: 20px;
    text-align: left;
  }

  .brand { order: 0; }
  .brand .logo { width: 28px; height: 28px; }

  .side-nav {
    order: 2;
    flex-direction: row;
    gap: 18px;
    flex-wrap: wrap;
    width: 100%;
  }
  .side-nav a { padding: 2px 0; font-size: var(--fs-s); }
  .side-nav a.is-active::after { display: none; }
  .side-nav a.is-active { border-bottom: 1px solid var(--accent); }

  .side-util {
    order: 1;
    flex-direction: row;
    margin-top: 0;
    padding-top: 0;
    gap: 12px;
  }

  .content { max-width: 100%; padding-bottom: 80px; }
  .content-foot { margin-top: 80px; }

  .article-nav { grid-template-columns: 1fr; gap: 24px; }
  .article-nav .right { text-align: left; }
}