:root {
  --color-paper: #f4f5f6;
  --color-white: #ffffff;
  --color-ink: #14181c;
  --color-ink-soft: #3d474f;
  --color-ink-mute: #6a757e;
  --color-rule: #d8dce3;
  --color-rule-strong: #c5ccd3;
  --color-wash: #eef1f3;
  --color-accent: #1f4e5c;
  --color-accent-soft: #e7eef0;
  --color-ok: #215c45;
  --color-warn: #6b5318;
  --color-danger: #8a3a3a;
  --color-danger-wash: #f6ecec;

  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;

  --font-sans: "Source Han Sans SC", "Noto Sans SC", "PingFang SC", "Hiragino Sans GB",
    "Microsoft YaHei UI", "Microsoft YaHei", "Segoe UI", system-ui, sans-serif;
  --font-serif: "Source Han Serif SC", "Noto Serif SC", "Songti SC", "STSong", "SimSun",
    "Times New Roman", Georgia, serif;
  --font-mono: "Cascadia Mono", "Segoe UI Mono", ui-monospace, "SFMono-Regular", Menlo,
    Consolas, monospace;

  --measure: 68rem;
  --nav-height: 3.5rem;
}

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

html { color-scheme: light; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font-sans);
  font-size: 15px;
  line-height: 1.65;
  color: var(--color-ink);
  background: var(--color-paper);
  -webkit-font-smoothing: antialiased;
}

a { color: var(--color-accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 0.18em; }
a:focus-visible,
button:focus-visible,
input:focus-visible,
textarea:focus-visible,
select:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

.skip {
  position: absolute;
  left: -999px;
  top: 0;
}
.skip:focus {
  left: var(--space-4);
  top: var(--space-2);
  z-index: 80;
  background: var(--color-white);
  padding: var(--space-2) var(--space-3);
  border: 1px solid var(--color-rule);
}

.top {
  position: sticky;
  top: 0;
  z-index: 30;
  display: flex;
  align-items: stretch;
  gap: var(--space-6);
  min-height: var(--nav-height);
  padding: 0 clamp(1.25rem, 4vw, 2.5rem);
  background: var(--color-white);
  border-bottom: 1px solid var(--color-rule);
  flex-wrap: wrap;
}

.brand {
  display: flex;
  flex-direction: column;
  justify-content: center;
  color: var(--color-ink);
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 1.02rem;
  letter-spacing: 0.01em;
  white-space: nowrap;
  text-decoration: none;
  padding: 0.65rem 0;
  border-right: 1px solid var(--color-rule);
  padding-right: var(--space-6);
  margin-right: 0.15rem;
}
.brand:hover { text-decoration: none; color: var(--color-accent); }
.brand small {
  display: block;
  font-family: var(--font-sans);
  font-weight: 400;
  font-size: 0.68rem;
  color: var(--color-ink-mute);
  letter-spacing: 0.12em;
  text-transform: lowercase;
  margin-top: 0.12rem;
}

.top nav {
  display: flex;
  gap: 0.15rem;
  flex: 1;
  flex-wrap: wrap;
  align-items: stretch;
}

.top nav a {
  display: inline-flex;
  align-items: center;
  color: var(--color-ink-soft);
  text-decoration: none;
  font-size: 0.86rem;
  letter-spacing: 0.02em;
  padding: 0 0.85rem;
  border-bottom: 2px solid transparent;
}
.top nav a:hover {
  color: var(--color-ink);
  text-decoration: none;
}
.top nav a.is-active {
  color: var(--color-ink);
  font-weight: 600;
  border-bottom-color: var(--color-accent);
}

.user-slot {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin-left: auto;
}
.user-name {
  font-size: 0.78rem;
  color: var(--color-ink-mute);
  font-variant-numeric: tabular-nums;
}

.top form { margin: 0; }

button,
.btn {
  font-family: inherit;
  font-size: 0.86rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  min-height: 2.35rem;
  padding: 0.45rem 1.05rem;
  border: 1px solid var(--color-accent);
  border-radius: 0;
  background: var(--color-accent);
  color: #f7fafb;
  cursor: pointer;
}
button:hover,
.btn:hover { background: #173d48; border-color: #173d48; }

button.ghost,
.btn-ghost {
  background: transparent;
  color: var(--color-ink-soft);
  border-color: var(--color-rule-strong);
}
button.ghost:hover,
.btn-ghost:hover {
  background: var(--color-wash);
  color: var(--color-ink);
}

button.danger,
.btn-danger {
  background: transparent;
  color: var(--color-danger);
  border-color: #d0b4b4;
}
button.danger:hover,
.btn-danger:hover { background: var(--color-danger-wash); }

main {
  padding: 2.1rem clamp(1.25rem, 4vw, 2.5rem) 4rem;
  max-width: var(--measure);
  margin: 0 auto;
}

h1 {
  margin: 0 0 0.55rem;
  font-family: var(--font-serif);
  font-size: 1.72rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  line-height: 1.28;
  color: var(--color-ink);
}
h2 {
  margin: 2.4rem 0 0.7rem;
  padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--color-rule);
  font-family: var(--font-serif);
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: 0.02em;
}
p { margin: 0 0 0.85rem; }
.lead {
  max-width: 40rem;
  color: var(--color-ink-soft);
  font-size: 0.95rem;
  margin-bottom: 1.6rem;
}
.muted { color: var(--color-ink-mute); font-size: 0.82rem; }

.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin: 0 0 1rem;
}
.chip {
  display: inline-flex;
  align-items: center;
  height: 1.7rem;
  padding: 0 0.65rem;
  border: 1px solid var(--color-rule);
  color: var(--color-ink-soft);
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  text-decoration: none;
  background: var(--color-white);
  white-space: nowrap;
}
.chip:hover {
  border-color: var(--color-ink);
  color: var(--color-ink);
  text-decoration: none;
}
.chip.is-on {
  border-color: var(--color-ink);
  color: var(--color-white);
  background: var(--color-ink);
}
.chip.tiny {
  height: 1.4rem;
  padding: 0 0.45rem;
  font-size: 0.7rem;
  margin: 0.1rem 0.15rem 0.1rem 0;
}

.admin-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
  margin: 0 0 1.2rem;
}
.admin-row form { margin: 0; }

button.switch {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  min-height: 2rem;
  padding: 0.15rem 0.55rem 0.15rem 0.2rem;
  border: 1px solid var(--color-rule-strong);
  background: transparent;
  color: var(--color-ink-soft);
  letter-spacing: 0;
}
button.switch:hover {
  background: var(--color-wash);
  border-color: var(--color-ink);
  color: var(--color-ink);
}
.switch-knob {
  width: 2.1rem;
  height: 1.15rem;
  border-radius: 999px;
  background: var(--color-rule);
  position: relative;
  flex: 0 0 auto;
}
.switch-knob::after {
  content: "";
  position: absolute;
  top: 0.12rem;
  left: 0.12rem;
  width: 0.9rem;
  height: 0.9rem;
  border-radius: 50%;
  background: var(--color-white);
  box-shadow: 0 0 0 1px rgb(20 24 28 / 0.08);
}
button.switch.is-on {
  border-color: var(--color-accent);
  color: var(--color-accent);
}
button.switch.is-on .switch-knob {
  background: var(--color-accent);
}
button.switch.is-on .switch-knob::after {
  left: auto;
  right: 0.12rem;
}
.switch-text {
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.04em;
}
.tag-cell { min-width: 11rem; }
.error { color: var(--color-danger); }
.ok { color: var(--color-ok); }

.cards {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  margin: 0 0 2.1rem;
  border-top: 1px solid var(--color-ink);
  border-bottom: 1px solid var(--color-rule);
  background: var(--color-white);
}
.card {
  display: block;
  background: transparent;
  border: none;
  border-right: 1px solid var(--color-rule);
  border-radius: 0;
  padding: 1.15rem 1.2rem 1.05rem;
  color: inherit;
  text-decoration: none;
}
.card:last-child { border-right: none; }
.card:hover {
  background: var(--color-wash);
  text-decoration: none;
}
.card strong {
  display: block;
  font-family: var(--font-serif);
  font-size: 1.85rem;
  font-weight: 600;
  color: var(--color-ink);
  letter-spacing: -0.02em;
  font-variant-numeric: tabular-nums;
  line-height: 1.1;
}
.card span {
  display: block;
  margin-top: 0.4rem;
  font-size: 0.72rem;
  font-weight: 500;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-ink-mute);
}

.table-wrap {
  overflow-x: auto;
  background: var(--color-white);
  border: none;
  border-top: 1px solid var(--color-ink);
  border-bottom: 1px solid var(--color-rule);
  border-radius: 0;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.84rem;
  line-height: 1.45;
}
th, td {
  padding: 0.62rem 0.85rem;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--color-rule);
}
th {
  position: sticky;
  top: 0;
  background: var(--color-white);
  color: var(--color-ink-mute);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  white-space: nowrap;
  border-bottom: 1px solid var(--color-ink);
}
tbody tr:nth-child(even) { background: transparent; }
tbody tr:hover { background: var(--color-wash); }
tbody tr:last-child td { border-bottom: none; }

.mono {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--color-ink-soft);
  word-break: break-all;
}

.search {
  display: flex;
  gap: 0;
  margin: 1.1rem 0 1.25rem;
  max-width: 36rem;
  border-bottom: 1px solid var(--color-ink);
}
.search input {
  flex: 1;
  border: none;
  border-radius: 0;
  min-height: 2.5rem;
  background: transparent;
  padding-left: 0;
}
.search input:focus {
  border: none;
  box-shadow: none;
  outline: none;
}
.search button {
  border: none;
  border-radius: 0;
  min-height: 2.5rem;
  padding-inline: 1.15rem;
}

form[action="/me/token"] {
  display: flex;
  gap: 0;
  max-width: 28rem;
  margin: 0.8rem 0 1.2rem;
  border-bottom: 1px solid var(--color-ink);
}
form[action="/me/token"] input {
  border: none;
  border-radius: 0;
  background: transparent;
  min-height: 2.5rem;
}
form[action="/me/token"] input:focus {
  box-shadow: none;
  outline: none;
}
form[action="/me/token"] button {
  border: none;
  border-radius: 0;
  white-space: nowrap;
}

input, textarea, select {
  width: 100%;
  min-height: 2.5rem;
  padding: 0.45rem 0.15rem;
  border: none;
  border-bottom: 1px solid var(--color-rule-strong);
  border-radius: 0;
  background: transparent;
  color: var(--color-ink);
  font-family: inherit;
  font-size: 0.95rem;
}
textarea {
  min-height: 6.5rem;
  resize: vertical;
  border: 1px solid var(--color-rule);
  padding: 0.65rem 0.75rem;
  background: var(--color-white);
}
input:focus, textarea:focus, select:focus {
  border-color: var(--color-accent);
  box-shadow: none;
  outline: none;
}

.stack {
  display: grid;
  gap: var(--space-5);
  max-width: 28rem;
  margin: 1.1rem 0 1.6rem;
}
.stack label, .login-card label {
  display: grid;
  gap: 0.3rem;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-ink-mute);
}
.inline {
  display: flex;
  gap: var(--space-2);
  align-items: center;
  font-weight: 400;
  letter-spacing: 0;
  text-transform: none;
  font-size: 0.9rem;
  color: var(--color-ink);
}
.inline input { width: auto; min-height: 1.1rem; }

.kv {
  display: grid;
  grid-template-columns: 6.5rem 1fr;
  gap: 0.65rem 1.5rem;
  background: transparent;
  border: none;
  border-top: 1px solid var(--color-ink);
  border-bottom: 1px solid var(--color-rule);
  border-radius: 0;
  padding: 1.05rem 0 0.9rem;
  margin: 0.6rem 0 1.8rem;
}
.kv dt {
  color: var(--color-ink-mute);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding-top: 0.15rem;
}
.kv dd { margin: 0; }

.lesson {
  background: transparent;
  border: none;
  border-top: 1px solid var(--color-rule);
  border-radius: 0;
  padding: 1.15rem 0 0.35rem;
  margin: 0;
}
.lesson h2 {
  margin: 0 0 0.45rem;
  padding: 0;
  border: none;
  font-size: 1.05rem;
}

.token-once {
  background: var(--color-accent-soft);
  color: var(--color-ink);
  border: none;
  border-left: 3px solid var(--color-accent);
  border-radius: 0;
  padding: 0.95rem 1.1rem;
  margin: 1rem 0 1.4rem;
}
.token-once pre {
  margin: 0.55rem 0 0;
  padding: 0.55rem 0;
  background: transparent;
  border: none;
  border-top: 1px solid rgb(31 78 92 / 0.18);
  font-family: var(--font-mono);
  font-size: 0.86rem;
  letter-spacing: 0.03em;
  white-space: pre-wrap;
  word-break: break-all;
}

.crumb {
  font-size: 0.8rem;
  margin-bottom: 0.85rem;
  color: var(--color-ink-mute);
}
code {
  font-family: var(--font-mono);
  font-size: 0.86em;
  background: var(--color-wash);
  padding: 0.05em 0.32em;
  border-radius: 0;
}

main ul {
  margin: 0.2rem 0 1rem;
  padding-left: 1.15rem;
}
main li { margin: 0.28rem 0; }

.login-body {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 2rem 1.25rem;
  background: var(--color-paper);
  color: var(--color-ink);
}
.login-card {
  width: min(22rem, 92vw);
  background: transparent;
  color: var(--color-ink);
  padding: 0.2rem 0 0;
  border: none;
  border-top: 2px solid var(--color-ink);
  border-radius: 0;
  box-shadow: none;
  display: grid;
  gap: 1.05rem;
}
.login-card h1 {
  margin: 0;
  font-size: 1.55rem;
}
.login-kicker {
  font-family: var(--font-sans);
  font-size: 0.68rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-ink-mute);
  font-weight: 600;
  padding-top: 1.15rem;
}
.login-card .muted {
  color: var(--color-ink-soft);
  margin: 0;
  font-size: 0.86rem;
  line-height: 1.55;
  max-width: 22rem;
}
.login-card button {
  width: 100%;
  min-height: 2.6rem;
  margin-top: 0.35rem;
}

.fold {
  margin: 0.4rem 0 1.6rem;
  border-top: 1px solid var(--color-ink);
  background: var(--color-white);
}
.fold > summary {
  cursor: pointer;
  list-style: none;
  padding: 0.85rem 1rem;
  font-family: var(--font-serif);
  font-size: 1.02rem;
  font-weight: 600;
  color: var(--color-ink);
}
.fold > summary::-webkit-details-marker { display: none; }
.fold > summary::after {
  content: "展开";
  float: right;
  font-family: var(--font-sans);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-ink-mute);
}
.fold[open] > summary::after { content: "收起"; }
.fold > *:not(summary) {
  margin-left: 1rem;
  margin-right: 1rem;
}
.fold > .stack { margin-top: 0.4rem; }
.fold > p:last-child,
.fold > form:last-child { padding-bottom: 1rem; }

.chain-block { margin: 0 0 1.35rem; }
.chain-kicker {
  margin: 0 0 0.55rem;
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-ink-mute);
  font-weight: 600;
}
.knowledge-chain {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  align-items: stretch;
  gap: 0;
  margin: 0;
  padding: 0;
  overflow-x: auto;
}
.knowledge-chain > li {
  display: flex;
  align-items: center;
  margin: 0;
  min-width: 0;
}
.knowledge-chain > li:not(:last-child)::after {
  content: "";
  width: 1.6rem;
  height: 0;
  border-top: 2px solid var(--color-accent);
  margin: 0 0.15rem;
  flex: 0 0 auto;
}
.chain-node {
  display: grid;
  gap: 0.18rem;
  min-width: 9.5rem;
  max-width: 14rem;
  padding: 0.7rem 0.8rem 0.75rem;
  background: var(--color-white);
  border: 1px solid var(--color-rule);
  border-left: 3px solid var(--color-accent);
  color: inherit;
  text-decoration: none;
}
.chain-node:hover {
  background: var(--color-accent-soft);
  text-decoration: none;
  border-color: var(--color-accent);
}
.chain-title {
  font-family: var(--font-serif);
  font-weight: 600;
  color: var(--color-ink);
}
.chain-meta,
.chain-note {
  display: block;
  font-size: 0.72rem;
  color: var(--color-ink-mute);
  line-height: 1.35;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.chain-note { color: var(--color-ink-soft); }

@media (max-width: 860px) {
  .cards { grid-template-columns: 1fr 1fr; }
  .card:nth-child(2) { border-right: none; }
  .card:nth-child(1),
  .card:nth-child(2) { border-bottom: 1px solid var(--color-rule); }
}

@media (max-width: 720px) {
  .brand {
    border-right: none;
    padding-right: 0;
    width: 100%;
  }
  .top { padding: 0 1rem; }
  main { padding: 1.35rem 1rem 3rem; }
  .kv { grid-template-columns: 1fr; }
  .user-name { display: none; }
  h1 { font-size: 1.4rem; }
  .cards { grid-template-columns: 1fr 1fr; }
}

.handoff {
  background: var(--color-white);
  border: 1px solid var(--color-rule);
  padding: 1rem 1.2rem 1.2rem;
  margin: 1rem 0 1.5rem;
}
.handoff .btn {
  display: inline-block;
  background: var(--color-accent);
  color: #fff;
  text-decoration: none;
  padding: 0.55rem 1rem;
}
.prompt-box {
  width: 100%;
  min-height: 12rem;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.45;
  padding: 0.75rem;
  border: 1px solid var(--color-rule);
  background: var(--color-wash);
  color: var(--color-ink);
  resize: vertical;
}

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