/* ============================================================
   Research Skill Stack — v1.0 · 2026-06-15
   research notebook + modern editorial + dark lab accent
   ============================================================ */

:root {
  /* light default */
  --bg: #f6f1e6;
  --bg-soft: #efe7d3;
  --bg-card: #fffdf6;
  --ink: #1d1c1a;
  --ink-soft: #4d4842;
  --ink-faint: #7a7367;
  --rule: #d6cdb7;
  --rule-soft: #ebe2c9;
  --accent: #b15a30;
  --accent-soft: #d88457;
  --lab: #1a2433;
  --lab-ink: #e7ebf1;
  --lab-faint: #6b7689;
  --good: #3fbf7f;
  --warn: #e9b949;
  --bad: #e98074;
  --link: #2e6cb6;
  --code-bg: #efe6cf;
  --shadow: 0 1px 0 rgba(60,40,10,0.06), 0 4px 14px rgba(60,40,10,0.06);
  --radius: 4px;
  --radius-lg: 8px;
  --max: 1180px;
  --gutter: 1.4rem;
  --serif: "Source Serif Pro", "Noto Serif SC", "PingFang SC", Georgia, serif;
  --sans: -apple-system, BlinkMacSystemFont, "Inter", "Helvetica Neue", "PingFang SC", "Microsoft Yahei", Arial, sans-serif;
  --mono: "JetBrains Mono", "Fira Code", ui-monospace, "SFMono-Regular", Menlo, monospace;
}

[data-theme="lab"] {
  --bg: #0e1116;
  --bg-soft: #161a22;
  --bg-card: #1b212b;
  --ink: #e7ebf1;
  --ink-soft: #b3bbc8;
  --ink-faint: #6b7689;
  --rule: #2a313d;
  --rule-soft: #1f252f;
  --accent: #e9b949;
  --accent-soft: #f0c97a;
  --lab: #f6f1e6;
  --lab-ink: #1d1c1a;
  --lab-faint: #4d4842;
  --good: #5fc294;
  --warn: #e9b949;
  --bad: #e98074;
  --link: #79b6f2;
  --code-bg: #161a22;
  --shadow: 0 1px 0 rgba(0,0,0,0.4), 0 4px 14px rgba(0,0,0,0.5);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 72px; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}
a { color: var(--link); text-decoration: none; border-bottom: 1px solid transparent; transition: border-color .15s; }
a:hover { border-bottom-color: var(--link); }
a:focus-visible { outline: 2px dashed var(--accent); outline-offset: 2px; border-radius: 2px; }
button { font-family: inherit; }
img, svg { max-width: 100%; display: block; }

.skip-link {
  position: absolute; left: -9999px;
}
.skip-link:focus {
  left: 1rem; top: 1rem; background: var(--ink); color: var(--bg);
  padding: .4rem .8rem; z-index: 999; border-radius: 4px;
}

/* ========== Header ========== */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: color-mix(in srgb, var(--bg) 90%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--rule);
}
.header-inner {
  max-width: var(--max);
  margin: 0 auto;
  padding: .7rem var(--gutter);
  display: flex; align-items: center; gap: 1.4rem;
}
.brand {
  display: inline-flex; align-items: center; gap: .55rem;
  font-weight: 700; color: var(--ink); border: none; font-size: .95rem;
}
.brand-mark {
  display: inline-grid; place-items: center;
  width: 26px; height: 26px;
  background: var(--ink); color: var(--bg);
  border-radius: var(--radius); font-size: .9rem;
}
.brand:hover { border: none; }
.topnav { display: flex; gap: 1rem; margin-left: auto; flex-wrap: wrap; }
.topnav a { color: var(--ink-soft); font-size: .85rem; border: none; padding: .2rem 0; }
.topnav a:hover { color: var(--ink); border: none; }
.theme-toggle {
  border: 1px solid var(--rule);
  background: var(--bg-card);
  color: var(--ink);
  padding: .35rem .65rem;
  border-radius: var(--radius);
  cursor: pointer;
  font-size: .8rem;
  font-weight: 600;
  letter-spacing: .03em;
}
.theme-toggle:hover { border-color: var(--ink-faint); }
[data-theme="notebook"] .theme-label-light { display: none; }
[data-theme="lab"] .theme-label-dark { display: none; }

/* ========== Hero ========== */
.hero {
  padding: 4.5rem var(--gutter) 3rem;
  border-bottom: 1px solid var(--rule);
  background:
    linear-gradient(180deg, transparent 0%, color-mix(in srgb, var(--bg-soft) 60%, transparent) 100%);
}
.hero-inner { max-width: 880px; margin: 0 auto; }
.hero-eyebrow {
  font-family: var(--mono); font-size: .8rem; letter-spacing: .12em;
  color: var(--ink-faint); margin: 0 0 1rem; text-transform: uppercase;
}
.hero-title {
  font-family: var(--serif);
  font-size: clamp(2.2rem, 4.6vw, 3.6rem);
  line-height: 1.15; margin: 0 0 1.2rem;
  letter-spacing: -.01em; color: var(--ink);
}
.hero-accent {
  background: linear-gradient(180deg, transparent 60%, color-mix(in srgb, var(--accent) 25%, transparent) 60%);
  padding: 0 .15em;
}
.hero-lede { font-size: 1.05rem; color: var(--ink-soft); max-width: 56ch; margin: 0 0 1.4rem; }
.hero-quote {
  font-family: var(--serif);
  font-size: 1.4rem; color: var(--ink);
  border-left: 3px solid var(--accent);
  padding: .4rem 0 .4rem 1rem;
  margin: 1.4rem 0 1.4rem;
  max-width: 56ch;
}
.hero-meta { display: flex; flex-wrap: wrap; gap: .5rem; margin: 1.4rem 0 1.6rem; }
.hero-chip {
  font-family: var(--mono); font-size: .75rem; letter-spacing: .04em;
  padding: .25rem .6rem; border: 1px solid var(--rule);
  border-radius: 99px; color: var(--ink-soft); background: var(--bg-card);
}
.hero-cta {
  display: inline-block; padding: .7rem 1.1rem;
  background: var(--ink); color: var(--bg);
  border: none; border-radius: var(--radius); font-weight: 600;
}
.hero-cta:hover { background: var(--accent); border: none; }

/* ========== Section base ========== */
.section { padding: 3.5rem var(--gutter); border-bottom: 1px solid var(--rule-soft); }
.section-inner { max-width: var(--max); margin: 0 auto; }
.block-head { margin-bottom: 2rem; }
.block-eyebrow {
  font-family: var(--mono); font-size: .75rem; letter-spacing: .14em;
  color: var(--ink-faint); text-transform: uppercase; margin: 0 0 .5rem;
}
.block-title {
  font-family: var(--serif);
  font-size: clamp(1.6rem, 2.8vw, 2.2rem);
  margin: 0 0 .6rem; color: var(--ink); letter-spacing: -.005em;
}
.muted { color: var(--ink-faint); font-weight: 400; }
.block-lede { color: var(--ink-soft); margin: 0; max-width: 70ch; }

/* ========== Skill Stack Map ========== */
.stack-list {
  list-style: none; padding: 0; margin: 0;
  display: grid; grid-template-columns: repeat(2, 1fr);
  gap: .8rem;
}
.stack-layer {
  --lc: var(--accent);
  position: relative;
  display: grid;
  grid-template-columns: 36px 1fr auto;
  align-items: center;
  gap: .6rem;
  padding: 1rem 1.1rem;
  background: var(--bg-card);
  border: 1px solid var(--rule);
  border-left: 4px solid var(--lc);
  border-radius: var(--radius);
  transition: transform .15s, box-shadow .15s, border-color .15s;
}
.stack-layer:hover { transform: translateY(-1px); box-shadow: var(--shadow); border-color: var(--ink-faint); }
.stack-no {
  font-family: var(--mono); font-size: .85rem; font-weight: 700;
  color: var(--lc);
}
.stack-name { font-weight: 600; color: var(--ink); font-size: 1rem; }
.stack-en { font-family: var(--mono); font-size: .75rem; color: var(--ink-faint); }
.stack-footnote {
  margin-top: 1.4rem; font-size: .9rem; color: var(--ink-soft);
  border-top: 1px dashed var(--rule); padding-top: 1rem;
}

/* ========== Translation ========== */
.translation-layout {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 2.4rem;
  align-items: start;
}
.toc {
  position: sticky; top: 80px;
  font-size: .9rem;
  border-right: 1px solid var(--rule);
  padding-right: 1.2rem;
}
.toc-title {
  font-family: var(--mono); font-size: .7rem; letter-spacing: .12em;
  color: var(--ink-faint); text-transform: uppercase; margin: 0 0 .8rem;
}
.toc-list { list-style: none; padding: 0; margin: 0 0 1.4rem; }
.toc-link {
  display: grid; grid-template-columns: 28px 1fr; align-items: center; gap: .35rem;
  padding: .45rem 0; color: var(--ink-soft);
  border: none; border-left: 2px solid transparent; padding-left: .55rem;
  margin-left: -.55rem;
  transition: color .12s, border-color .12s;
}
.toc-link:hover { color: var(--ink); border: none; }
.toc-link.is-active { color: var(--accent); border-left-color: var(--accent); }
.toc-no { font-family: var(--mono); font-size: .72rem; color: var(--ink-faint); }
.toc-link.is-active .toc-no { color: var(--accent); }
.toc-name { line-height: 1.3; }
.toc-progress { font-size: .8rem; color: var(--ink-soft); }
.toc-progress-label { display: block; margin-bottom: .3rem; font-family: var(--mono); font-size: .7rem; letter-spacing: .1em; color: var(--ink-faint); text-transform: uppercase; }
.toc-progress-track { height: 4px; background: var(--rule-soft); border-radius: 99px; overflow: hidden; }
.toc-progress-bar { height: 100%; width: 0%; background: var(--accent); transition: width .25s; }
.toc-progress-pct { display: inline-block; margin-top: .35rem; font-family: var(--mono); font-size: .7rem; color: var(--ink-faint); }

.article { min-width: 0; }
.article-section {
  padding: 1.4rem 0 2rem;
  border-top: 1px solid var(--rule-soft);
}
.article-section:first-child { border-top: none; padding-top: 0; }
.section-head { margin-bottom: 1rem; }
.section-no {
  font-family: var(--mono); font-size: .72rem; letter-spacing: .12em;
  color: var(--ink-faint); display: block; margin-bottom: .3rem;
}
.section-title {
  font-family: var(--serif);
  font-size: 1.7rem; line-height: 1.25;
  margin: 0 0 .8rem; color: var(--ink);
  letter-spacing: -.005em;
}
.section-body p {
  margin: 0 0 1.05rem;
  color: var(--ink);
  font-size: 1.02rem;
}
.section-body p:last-child { margin-bottom: 0; }
.section-body strong { color: var(--ink); font-weight: 700; }
.section-body em { font-style: italic; color: var(--ink); }
.section-body code {
  font-family: var(--mono); font-size: .88em;
  background: var(--code-bg); padding: .1em .35em; border-radius: 3px;
  color: var(--ink);
}

/* ========== Background cards ========== */
.bg-card-grid {
  list-style: none; padding: 0; margin: 0;
  display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1rem;
}
.bg-card {
  background: var(--bg-card);
  border: 1px solid var(--rule);
  border-radius: var(--radius-lg);
  padding: 1.1rem 1.2rem 1rem;
  display: flex; flex-direction: column; gap: .55rem;
  box-shadow: var(--shadow);
  transition: transform .15s, border-color .15s;
}
.bg-card:hover { border-color: var(--ink-faint); transform: translateY(-2px); }
.bg-card-head {
  display: flex; justify-content: space-between; align-items: baseline; gap: .6rem;
}
.bg-card-name { font-family: var(--serif); font-size: 1.15rem; color: var(--ink); font-weight: 700; }
.bg-card-badge {
  --badge: #888;
  font-family: var(--mono); font-size: .68rem; letter-spacing: .04em;
  padding: .15rem .5rem; border-radius: 99px;
  background: color-mix(in srgb, var(--badge) 18%, transparent);
  color: var(--badge);
  border: 1px solid color-mix(in srgb, var(--badge) 35%, transparent);
  white-space: nowrap;
}
.bg-card-role { color: var(--ink-soft); font-size: .85rem; margin: 0; }
.bg-card-work { color: var(--ink); font-size: .9rem; margin: 0; }
.bg-card-idea, .bg-card-rel { color: var(--ink-soft); font-size: .9rem; margin: 0; line-height: 1.55; }
.card-label {
  display: inline-block; font-family: var(--mono); font-size: .7rem; letter-spacing: .1em;
  color: var(--accent); margin-right: .35rem; text-transform: uppercase;
}
.card-source { color: var(--ink-soft); font-size: .82rem; margin: .2rem 0 0; word-break: break-all; }
.card-note { color: var(--ink-faint); font-size: .78rem; margin: .15rem 0 0; font-style: italic; }

/* ========== Log template ========== */
.log-form {
  background: var(--bg-card);
  border: 1px solid var(--rule);
  border-radius: var(--radius-lg);
  padding: 1.2rem 1.2rem 1rem;
  display: flex; flex-direction: column; gap: 1rem;
  box-shadow: var(--shadow);
}
.log-field { display: flex; flex-direction: column; gap: .3rem; }
.log-label {
  font-family: var(--mono); font-size: .78rem; letter-spacing: .06em;
  color: var(--ink); text-transform: uppercase;
}
.log-field textarea {
  font-family: var(--sans);
  font-size: .95rem;
  border: 1px solid var(--rule);
  background: var(--bg);
  color: var(--ink);
  border-radius: var(--radius);
  padding: .6rem .7rem;
  resize: vertical;
  min-height: 56px;
}
.log-field textarea:focus {
  outline: none; border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 18%, transparent);
}
.log-actions { display: flex; align-items: center; gap: .6rem; flex-wrap: wrap; }
.btn {
  font-size: .9rem; padding: .55rem 1rem; border-radius: var(--radius);
  cursor: pointer; border: 1px solid transparent; font-weight: 600;
}
.btn-primary { background: var(--ink); color: var(--bg); border-color: var(--ink); }
.btn-primary:hover { background: var(--accent); border-color: var(--accent); }
.btn-ghost { background: transparent; color: var(--ink-soft); border-color: var(--rule); }
.btn-ghost:hover { border-color: var(--ink-faint); color: var(--ink); }
.log-toast { color: var(--good); font-size: .85rem; opacity: 0; transition: opacity .2s; }
.log-toast.is-show { opacity: 1; }
.log-foot { font-size: .8rem; color: var(--ink-faint); margin-top: .8rem; }

/* ========== Taste training ========== */
.taste-loop {
  list-style: none; padding: 0; margin: 0;
  display: grid; grid-template-columns: repeat(4, 1fr); gap: .8rem;
  counter-reset: taste;
}
.taste-step {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--rule);
  border-radius: var(--radius-lg);
  padding: 1.2rem 1rem 1rem 3rem;
  box-shadow: var(--shadow);
}
.taste-step::before {
  counter-increment: taste;
  content: counter(taste);
  position: absolute; left: .9rem; top: 1rem;
  width: 28px; height: 28px; border-radius: 50%;
  background: var(--ink); color: var(--bg);
  display: grid; place-items: center;
  font-family: var(--mono); font-size: .85rem; font-weight: 700;
}
.taste-title { margin: 0 0 .4rem; font-size: 1rem; color: var(--ink); }
.taste-step p { color: var(--ink-soft); font-size: .9rem; margin: 0; line-height: 1.5; }

/* ========== Error buckets ========== */
.error-buckets { list-style: none; padding: 0; margin: 0 0 1.2rem; display: flex; flex-direction: column; gap: .6rem; }
.error-bucket {
  --bc: var(--accent);
  background: var(--bg-card);
  border: 1px solid var(--rule);
  border-left: 4px solid var(--bc);
  border-radius: var(--radius);
  overflow: hidden;
  transition: background .15s;
}
.error-bucket.is-highlight { background: color-mix(in srgb, var(--bc) 10%, var(--bg-card)); }
.bucket-row {
  display: grid; grid-template-columns: 18px 1fr auto;
  align-items: center; gap: .7rem;
  width: 100%;
  background: none; border: none; padding: .8rem 1rem;
  font-size: 1rem; color: var(--ink); text-align: left; cursor: pointer;
}
.bucket-row:hover { background: var(--bg-soft); }
.bucket-dot { width: 10px; height: 10px; border-radius: 50%; background: var(--bc); }
.bucket-label { font-weight: 600; }
.bucket-count {
  font-family: var(--mono); font-size: .9rem;
  background: color-mix(in srgb, var(--bc) 22%, transparent);
  color: var(--bc);
  padding: .1rem .55rem; border-radius: 99px; min-width: 38px; text-align: center;
}
.bucket-example {
  margin: 0; padding: 0 1rem .8rem 2.2rem;
  color: var(--ink-soft); font-size: .88rem;
  display: none;
}
.error-bucket.is-open .bucket-example { display: block; }
.bucket-takeaway {
  margin: 0; padding: .8rem 1rem;
  background: var(--bg-soft); border-radius: var(--radius);
  color: var(--ink-soft); font-size: .92rem;
}

/* ========== 7-day plan ========== */
.day-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: .8rem;
}
.day-card {
  background: var(--bg-card);
  border: 1px solid var(--rule);
  border-radius: var(--radius-lg);
  padding: 1rem 1.1rem;
  display: flex; flex-direction: column; gap: .6rem;
  box-shadow: var(--shadow);
  transition: border-color .15s;
}
.day-card.is-done { border-color: var(--good); background: color-mix(in srgb, var(--good) 8%, var(--bg-card)); }
.day-head { display: flex; align-items: baseline; gap: .55rem; }
.day-no {
  font-family: var(--mono); font-size: .8rem; color: var(--accent);
  background: color-mix(in srgb, var(--accent) 15%, transparent);
  padding: .15rem .55rem; border-radius: 99px;
}
.day-theme { font-size: 1.05rem; color: var(--ink); margin: 0; }
.day-tasks { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: .35rem; }
.day-tasks li {
  font-size: .9rem; color: var(--ink-soft);
  padding-left: 1.3rem; position: relative; cursor: pointer;
  user-select: none;
}
.day-tasks li::before {
  content: ""; position: absolute; left: 0; top: .5em;
  width: 12px; height: 12px; border: 1.5px solid var(--ink-faint);
  border-radius: 3px; background: var(--bg);
  transition: background .12s, border-color .12s;
}
.day-tasks li.is-done { color: var(--ink-faint); text-decoration: line-through; }
.day-tasks li.is-done::before { background: var(--good); border-color: var(--good); }
.plan-progress {
  text-align: center; font-family: var(--mono); font-size: .9rem;
  color: var(--ink-soft); margin: 1.4rem 0 0;
}
.plan-progress span { color: var(--accent); font-weight: 700; }

/* ========== Takeaways ========== */
.takeaway-list {
  list-style: none; padding: 0; margin: 0;
  display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1rem;
  counter-reset: tk;
}
.takeaway {
  background: var(--bg-card);
  border: 1px solid var(--rule);
  border-radius: var(--radius-lg);
  padding: 1.2rem 1.2rem 1.2rem 3.2rem;
  position: relative;
  box-shadow: var(--shadow);
}
.takeaway::before {
  counter-increment: tk;
  content: "0" counter(tk);
  position: absolute; left: 1.1rem; top: 1.1rem;
  font-family: var(--mono); font-size: .75rem; color: var(--accent);
  background: color-mix(in srgb, var(--accent) 15%, transparent);
  padding: .15rem .45rem; border-radius: 4px; font-weight: 700;
}
.takeaway-title { font-size: 1.05rem; color: var(--ink); margin: 0 0 .4rem; }
.takeaway p { color: var(--ink-soft); font-size: .92rem; margin: 0; line-height: 1.55; }

/* ========== Further reading ========== */
.ref-list { list-style: none; padding: 0; margin: 0 0 1.2rem; display: flex; flex-direction: column; gap: .55rem; }
.ref-list li {
  font-size: .92rem; color: var(--ink-soft);
  padding: .55rem .8rem;
  background: var(--bg-card);
  border: 1px solid var(--rule-soft);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius);
}
.ref-list strong { color: var(--ink); }
.ref-list em { color: var(--ink); font-style: italic; }
.ref-note { font-size: .8rem; color: var(--ink-faint); font-style: italic; }

/* ========== Footer ========== */
.site-footer { padding: 1.6rem var(--gutter); border-top: 1px solid var(--rule); background: var(--bg-soft); }
.footer-inner { max-width: var(--max); margin: 0 auto; text-align: center; }
.footer-line { color: var(--ink-soft); font-size: .82rem; margin: .2rem 0; }
.footer-meta { color: var(--ink-faint); }

/* ========== Responsive ========== */
@media (max-width: 880px) {
  .translation-layout { grid-template-columns: 1fr; }
  .toc { position: static; border-right: none; border-bottom: 1px solid var(--rule); padding: 0 0 1.2rem; margin-bottom: 1.2rem; }
  .taste-loop { grid-template-columns: repeat(2, 1fr); }
  .stack-list { grid-template-columns: 1fr; }
  .topnav { display: none; }
  .header-inner { gap: .6rem; }
  .hero { padding: 3rem var(--gutter) 2rem; }
  .section { padding: 2.4rem var(--gutter); }
}
@media (max-width: 480px) {
  .taste-loop { grid-template-columns: 1fr; }
  .hero-meta { gap: .35rem; }
  .hero-chip { font-size: .68rem; padding: .15rem .45rem; }
  .log-actions { gap: .4rem; }
  .btn { width: 100%; text-align: center; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; }
}