:root {
  color-scheme: dark;
  --bg: #090d14;
  --bg-soft: #0d131e;
  --panel: #111827;
  --panel-2: #161f31;
  --panel-3: #1c2740;
  --border: #26324a;
  --border-strong: #344566;
  --text: #e9eef8;
  --muted: #95a3ba;
  --faint: #6f7d95;
  --accent: #7d9cff;
  --accent-2: #63d6b4;
  --accent-3: #f0c36a;
  --danger: #ff7d91;
  --danger-soft: rgba(255, 125, 145, .13);
  --ok: #5cd6a8;
  --ok-soft: rgba(92, 214, 168, .13);
  --warn: #f0c36a;
  --warn-soft: rgba(240, 195, 106, .13);
  --shadow: 0 18px 50px rgba(0, 0, 0, .34);
  --shadow-soft: 0 8px 26px rgba(0, 0, 0, .18);
  --radius: 18px;
  --radius-sm: 12px;
  --radius-xs: 9px;
  --gap: clamp(12px, 1.5vw, 22px);
  --pad: clamp(16px, 2.2vw, 30px);
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", "Cascadia Code", Menlo, Consolas, monospace;
}

[data-theme="light"] {
  color-scheme: light;
  --bg: #f4f7fc;
  --bg-soft: #eef3fb;
  --panel: #ffffff;
  --panel-2: #f7f9fe;
  --panel-3: #eef3fb;
  --border: #dce4f1;
  --border-strong: #c3cfe3;
  --text: #162033;
  --muted: #5d6b82;
  --faint: #8492a8;
  --accent: #3c63f0;
  --accent-2: #149b7d;
  --accent-3: #b7791f;
  --danger: #d94860;
  --danger-soft: rgba(217, 72, 96, .1);
  --ok: #128a6e;
  --ok-soft: rgba(18, 138, 110, .1);
  --warn: #a66b14;
  --warn-soft: rgba(166, 107, 20, .1);
  --shadow: 0 18px 44px rgba(28, 46, 84, .12);
  --shadow-soft: 0 8px 24px rgba(28, 46, 84, .08);
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }

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

body {
  margin: 0;
  min-block-size: 100dvh;
  color: var(--text);
  background:
    radial-gradient(900px 520px at 8% -8%, rgba(125, 156, 255, .16), transparent 62%),
    radial-gradient(760px 460px at 105% 4%, rgba(99, 214, 180, .12), transparent 58%),
    linear-gradient(180deg, var(--bg) 0%, var(--bg-soft) 100%);
  background-attachment: fixed;
  font-family: var(--font);
  font-size: clamp(14px, 1.05vw + 11px, 17px);
  line-height: 1.6;
  text-rendering: optimizeLegibility;
  overflow-wrap: anywhere;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: .18em; }

button, input, select, textarea { font: inherit; color: inherit; }
button, a, input, select, textarea { -webkit-tap-highlight-color: transparent; touch-action: manipulation; }
button { cursor: pointer; }
svg { display: block; }

:focus-visible {
  outline: 3px solid var(--accent);
  outline: 3px solid color-mix(in srgb, var(--accent) 70%, transparent);
  outline-offset: 2px;
  border-radius: 6px;
}

::selection { background: color-mix(in srgb, var(--accent) 34%, transparent); }

.svg-sprite { position: absolute; inline-size: 0; block-size: 0; overflow: hidden; }

.ico {
  inline-size: 1.1em;
  block-size: 1.1em;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
  flex: none;
}

.muted { color: var(--muted); }
.tiny { font-size: .78rem; }
.small { font-size: .88rem; }
.grow { flex: 1 1 auto; min-inline-size: 0; }
.row { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.wrap { flex-wrap: wrap; }
.center { text-align: center; }
.nowrap { white-space: nowrap; }
.sr-only {
  position: absolute;
  inline-size: 1px;
  block-size: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

code, kbd, pre { font-family: var(--mono); }
code {
  padding: .14em .38em;
  border-radius: 6px;
  background: var(--panel-3);
  border: 1px solid var(--border);
  font-size: .88em;
  overflow-wrap: anywhere;
}
pre.code {
  margin: 0;
  padding: 14px;
  overflow: auto;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--bg);
  line-height: 1.55;
  font-size: .82rem;
}

.app-shell {
  display: flex;
  flex-direction: column;
  min-block-size: 100dvh;
}

/* ---------------------------------------------------------------- top bar */
.topbar {
  position: sticky;
  inset-block-start: 0;
  z-index: 30;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 6px;
  min-block-size: 60px;
  padding: 8px clamp(8px, 2vw, 24px);
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  border-block-end: 1px solid color-mix(in srgb, var(--border) 80%, transparent);
  backdrop-filter: blur(18px) saturate(1.25);
  -webkit-backdrop-filter: blur(18px) saturate(1.25);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: clamp(4px, .7vw, 8px);
  color: var(--text);
  text-decoration: none;
  flex: none;
  min-inline-size: 0;
}
.brand:hover { text-decoration: none; }
.brand-mark {
  display: grid;
  place-items: center;
  inline-size: clamp(28px, 3vw, 34px);
  block-size: clamp(28px, 3vw, 34px);
  border-radius: clamp(8px, 1vw, 11px);
  background: linear-gradient(145deg, var(--accent), var(--accent-2));
  color: #06101d;
  font-weight: 900;
  font-size: clamp(1rem, 1.4vw, 1.2rem);
  box-shadow: 0 10px 26px rgba(125, 156, 255, .28);
  flex: none;
}
.brand-text { display: flex; flex-direction: column; line-height: 1.1; min-inline-size: 0; }
.brand-text strong { font-size: clamp(.82rem, 1vw, .96rem); letter-spacing: .02em; }
.brand-text small { display: none; }

.nav {
  display: flex;
  align-items: center;
  flex-wrap: nowrap;
  gap: 0;
  min-inline-size: 0;
}
.nav > a,
.nav-more-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 5px;
  min-block-size: 44px;
  padding: 6px clamp(3px, .6vw, 8px);
  border-radius: 999px;
  color: var(--muted);
  text-decoration: none;
  font-size: clamp(.76rem, .86vw, .88rem);
  font-weight: 650;
  border: 1px solid transparent;
  background: transparent;
  white-space: nowrap;
  flex: none;
  transition: background .18s ease, color .18s ease, border-color .18s ease;
}
.nav > a:hover,
.nav-more-btn:hover { color: var(--text); background: var(--panel-2); text-decoration: none; }
.nav > a.active,
.nav-more-btn.active {
  color: var(--text);
  background: linear-gradient(180deg, var(--panel-3), var(--panel-2));
  border-color: var(--border);
  box-shadow: var(--shadow-soft);
}
.nav > a.active .ico,
.nav-more-btn.active .ico { color: var(--accent); }

.top-actions { display: flex; align-items: center; justify-content: flex-end; gap: 4px; }
.dropdown { position: relative; flex: none; }
.nav-more { position: relative; }
.user-btn {
  display: inline-flex;
  align-items: center;
  gap: 0;
  min-block-size: 44px;
  padding: 4px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--panel);
  color: var(--muted);
  transition: background .18s ease, border-color .18s ease, color .18s ease;
}
.user-btn:hover { background: var(--panel-2); border-color: var(--border-strong); color: var(--text); }
.user-btn .ico { inline-size: .8em; block-size: .8em; }
.user-avatar {
  display: grid;
  place-items: center;
  inline-size: clamp(28px, 3vw, 32px);
  block-size: clamp(28px, 3vw, 32px);
  border-radius: 999px;
  background: linear-gradient(145deg, var(--accent), var(--accent-2));
  color: #06101d;
  font-size: .82rem;
  font-weight: 800;
  line-height: 1;
  text-transform: uppercase;
}
.dropdown-menu {
  position: absolute;
  inset-block-start: calc(100% + 8px);
  inset-inline-end: 0;
  z-index: 60;
  display: flex;
  flex-direction: column;
  gap: 2px;
  min-inline-size: 190px;
  padding: 6px;
  border-radius: 14px;
  border: 1px solid var(--border-strong);
  background: var(--panel);
  box-shadow: var(--shadow);
}
.dropdown-menu a,
.dropdown-menu .menu-item {
  display: flex;
  align-items: center;
  gap: 10px;
  inline-size: 100%;
  min-block-size: 44px;
  padding: 8px 10px;
  border: 0;
  border-radius: 10px;
  background: transparent;
  color: var(--text);
  font: inherit;
  font-size: .88rem;
  font-weight: 600;
  text-align: start;
  text-decoration: none;
}
.dropdown-menu a:hover,
.dropdown-menu .menu-item:hover { background: var(--panel-2); text-decoration: none; }
.dropdown-menu a.active { color: var(--accent); background: color-mix(in srgb, var(--accent) 11%, var(--panel)); }
.dropdown-menu .ico { color: var(--muted); }
.menu-header {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 8px 10px 10px;
  margin-block-end: 4px;
  border-block-end: 1px solid var(--border);
}
.menu-header strong { font-size: .9rem; }
.menu-header small { color: var(--muted); font-size: .72rem; }

/* ------------------------------------------------------------------- page */
.page {
  inline-size: min(100%, 1240px);
  margin-inline: auto;
  padding: clamp(16px, 2.6vw, 38px) clamp(14px, 2.4vw, 34px) clamp(32px, 5vw, 64px);
  flex: 1 1 auto;
  min-inline-size: 0;
  animation: page-in .26s ease both;
}
@keyframes page-in { from { opacity: 0; transform: translateY(5px); } to { opacity: 1; transform: none; } }

.page-head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px 20px;
  margin-block-end: clamp(16px, 2.2vw, 28px);
}
.page-head h1 { margin: 0; font-size: clamp(1.5rem, 2.2vw + .8rem, 2.35rem); line-height: 1.15; letter-spacing: -.02em; }
.page-head p { margin: 6px 0 0; color: var(--muted); max-inline-size: 70ch; }

.footer {
  padding: 18px clamp(14px, 2.4vw, 34px) 28px;
  text-align: center;
  border-block-start: 1px solid color-mix(in srgb, var(--border) 55%, transparent);
}

/* ------------------------------------------------------------------ cards */
.card {
  background: linear-gradient(180deg, var(--panel), color-mix(in srgb, var(--panel) 86%, var(--bg)));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-soft);
  padding: var(--pad);
  min-inline-size: 0;
}
.card.flat { box-shadow: none; background: var(--panel-2); }
.card h2, .card h3 { margin: 0 0 8px; line-height: 1.25; }
.card h2 { font-size: clamp(1.05rem, 1.1vw + .8rem, 1.35rem); }
.card h3 { font-size: 1.02rem; }
.card p { margin: 0 0 10px; }
.card p:last-child { margin-block-end: 0; }
.card-head { display: flex; align-items: flex-start; justify-content: space-between; gap: 12px; flex-wrap: wrap; margin-block-end: 12px; }

.hero {
  display: flex;
  flex-wrap: wrap;
  gap: var(--gap);
  margin-block-end: var(--gap);
}
.hero-main {
  flex: 2.2 1 min(100%, 460px);
  min-inline-size: 0;
  position: relative;
  overflow: hidden;
  background:
    radial-gradient(520px 240px at 88% 10%, rgba(125, 156, 255, .23), transparent 66%),
    linear-gradient(145deg, var(--panel-2), var(--panel));
}
.hero-main::after {
  content: "∫";
  position: absolute;
  inset-inline-end: 8%;
  inset-block-end: -32%;
  font-size: clamp(10rem, 22vw, 18rem);
  line-height: 1;
  color: color-mix(in srgb, var(--accent) 9%, transparent);
  pointer-events: none;
}
.hero-side { flex: 1 1 min(100%, 250px); min-inline-size: 0; }
.hero h1 { margin: 0 0 8px; font-size: clamp(1.5rem, 2.4vw + .7rem, 2.5rem); letter-spacing: -.03em; line-height: 1.08; }
.hero .lede { color: var(--muted); max-inline-size: 52ch; margin: 0 0 18px; }

.grid-auto {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 220px), 1fr));
  gap: var(--gap);
}
.grid-tight {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 150px), 1fr));
  gap: 12px;
}
.stack { display: flex; flex-direction: column; gap: var(--gap); }
.stack-sm { display: flex; flex-direction: column; gap: 10px; }

.metric { display: flex; flex-direction: column; gap: 4px; }
.metric .label { color: var(--muted); font-size: .78rem; letter-spacing: .06em; text-transform: uppercase; }
.metric .value { font-size: clamp(1.45rem, 1.7vw + .8rem, 2rem); font-weight: 780; line-height: 1.05; font-variant-numeric: tabular-nums; }
.metric .hint { color: var(--faint); font-size: .76rem; }

.stat-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 22px;
  align-items: stretch;
}
.stat-strip > .metric { flex: 1 1 120px; }

/* ----------------------------------------------------------------- buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-block-size: 44px;
  padding: 9px 16px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--text);
  font-weight: 650;
  font-size: .92rem;
  text-decoration: none;
  transition: background .18s ease, border-color .18s ease, transform .18s ease, color .18s ease;
}
.btn:hover { background: var(--panel-3); border-color: var(--border-strong); text-decoration: none; }
.btn:active { transform: translateY(1px) scale(.995); }
.btn-primary {
  background: linear-gradient(145deg, var(--accent), color-mix(in srgb, var(--accent) 74%, var(--accent-2)));
  border-color: transparent;
  color: #07101d;
  box-shadow: 0 10px 24px rgba(125, 156, 255, .24);
}
.btn-primary:hover { background: linear-gradient(145deg, color-mix(in srgb, var(--accent) 88%, white), var(--accent-2)); }
.btn-ghost { background: transparent; }
.btn-danger { color: var(--danger); border-color: color-mix(in srgb, var(--danger) 40%, var(--border)); background: var(--danger-soft); }
.btn-wide { inline-size: 100%; }
.btn-sm { min-block-size: 38px; padding: 6px 12px; font-size: .84rem; }
.btn:disabled { opacity: .48; cursor: not-allowed; transform: none; }

.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-block-size: 44px;
  padding: 7px 13px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--muted);
  font-size: .84rem;
  font-weight: 650;
  transition: background .18s ease, color .18s ease, border-color .18s ease;
}
.chip:hover { color: var(--text); border-color: var(--border-strong); }
.chip.active { color: var(--text); border-color: color-mix(in srgb, var(--accent) 55%, var(--border)); background: color-mix(in srgb, var(--accent) 15%, var(--panel)); }
.chip .count { color: var(--faint); font-variant-numeric: tabular-nums; }
.chip.tier-A { border-color: color-mix(in srgb, var(--accent) 50%, var(--border)); }
.chip.tier-B { border-color: color-mix(in srgb, var(--accent-2) 45%, var(--border)); }
.chip.tier-C { border-color: color-mix(in srgb, var(--accent-3) 45%, var(--border)); }

.segmented {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  padding: 4px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  inline-size: fit-content;
  max-inline-size: 100%;
}
.segmented button {
  min-block-size: 40px;
  padding: 6px 14px;
  border: 0;
  border-radius: 10px;
  background: transparent;
  color: var(--muted);
  font-weight: 650;
  font-size: .86rem;
}
.segmented button.active { background: var(--panel-3); color: var(--text); box-shadow: var(--shadow-soft); }

/* ------------------------------------------------------------------ forms */
.field { display: flex; flex-direction: column; gap: 6px; font-size: .84rem; font-weight: 650; color: var(--muted); }
.field > span { color: var(--muted); }
input, select, textarea {
  inline-size: 100%;
  min-block-size: 44px;
  padding: 10px 12px;
  border-radius: 11px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--text);
  outline: none;
  transition: border-color .18s ease, background .18s ease, box-shadow .18s ease;
}
input:focus, select:focus, textarea:focus {
  border-color: color-mix(in srgb, var(--accent) 62%, var(--border));
  background: var(--panel);
  box-shadow: 0 0 0 4px color-mix(in srgb, var(--accent) 14%, transparent);
}
input::placeholder, textarea::placeholder { color: var(--faint); }
textarea { min-block-size: 72px; resize: vertical; }
select { appearance: none; background-image: linear-gradient(45deg, transparent 50%, var(--muted) 50%), linear-gradient(135deg, var(--muted) 50%, transparent 50%); background-position: calc(100% - 18px) 50%, calc(100% - 13px) 50%; background-size: 5px 5px, 5px 5px; background-repeat: no-repeat; padding-inline-end: 34px; }
.form-stack { display: flex; flex-direction: column; gap: 14px; }
.form-error { min-block-size: 1.3em; margin: 0; color: var(--danger); font-size: .84rem; }

/* ------------------------------------------------------------------ login */
.login-shell {
  min-block-size: 100dvh;
  display: grid;
  place-items: center;
  padding: clamp(18px, 4vw, 48px);
}
.login-card { inline-size: min(100%, 430px); padding: clamp(22px, 3.4vw, 38px); }
.login-card h1 { margin: 22px 0 6px; font-size: clamp(1.5rem, 2.4vw + .6rem, 2.05rem); letter-spacing: -.02em; }
.login-card > p { margin: 0 0 20px; }
.brand-login { margin-block-end: 4px; }

/* ------------------------------------------------------------------- lists */
.list { display: flex; flex-direction: column; gap: 8px; margin: 0; padding: 0; list-style: none; }
.list-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  padding: 11px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  background: var(--panel-2);
}
.list-item:hover { border-color: var(--border); background: var(--panel-3); }
.list-item .title { font-weight: 650; }
.list-item .meta { color: var(--muted); font-size: .8rem; }

.badge {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 3px 9px;
  border-radius: 999px;
  font-size: .72rem;
  font-weight: 750;
  letter-spacing: .02em;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--muted);
  white-space: nowrap;
}
.badge-tier-A { color: var(--accent); border-color: color-mix(in srgb, var(--accent) 45%, var(--border)); background: color-mix(in srgb, var(--accent) 12%, var(--panel)); }
.badge-tier-B { color: var(--accent-2); border-color: color-mix(in srgb, var(--accent-2) 45%, var(--border)); background: color-mix(in srgb, var(--accent-2) 10%, var(--panel)); }
.badge-tier-C { color: var(--accent-3); border-color: color-mix(in srgb, var(--accent-3) 45%, var(--border)); background: color-mix(in srgb, var(--accent-3) 10%, var(--panel)); }
.badge-ok { color: var(--ok); border-color: color-mix(in srgb, var(--ok) 42%, var(--border)); background: var(--ok-soft); }
.badge-warn { color: var(--warn); border-color: color-mix(in srgb, var(--warn) 42%, var(--border)); background: var(--warn-soft); }
.badge-danger { color: var(--danger); border-color: color-mix(in srgb, var(--danger) 42%, var(--border)); background: var(--danger-soft); }

.bar {
  inline-size: 100%;
  block-size: 7px;
  border-radius: 999px;
  background: var(--panel-3);
  overflow: hidden;
}
.bar > span {
  display: block;
  block-size: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  transition: inline-size .4s ease;
}
.bar.warm > span { background: linear-gradient(90deg, var(--accent-3), var(--danger)); }

/* ------------------------------------------------------------------ knowledge map */
.kp-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 250px), 1fr));
  gap: 10px;
}
.kp-card {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 13px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  text-align: start;
  text-decoration: none;
  min-inline-size: 0;
  transition: transform .16s ease, border-color .16s ease, background .16s ease;
}
.kp-card:hover { transform: translateY(-1px); border-color: var(--border-strong); background: var(--panel-2); text-decoration: none; }
.kp-card .kp-top { display: flex; align-items: flex-start; justify-content: space-between; gap: 8px; }
.kp-card .kp-title { font-weight: 700; line-height: 1.3; }
.kp-card .kp-id { color: var(--faint); font-size: .72rem; font-family: var(--mono); }
.kp-card .kp-meta { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; color: var(--muted); font-size: .75rem; }
.kp-card .kp-foot { display: flex; align-items: center; gap: 8px; margin-block-start: auto; }
.chapter-block { margin-block-end: clamp(18px, 2.6vw, 32px); }
.chapter-head { display: flex; align-items: baseline; justify-content: space-between; gap: 10px; flex-wrap: wrap; margin-block-end: 10px; }
.chapter-head h2 { margin: 0; font-size: 1.05rem; }
.chapter-head .chapter-code { color: var(--faint); font-family: var(--mono); font-size: .75rem; }

/* ------------------------------------------------------------------ notes */
.note-layout { display: flex; flex-wrap: wrap; gap: var(--gap); align-items: flex-start; }
.note-main { flex: 3 1 min(100%, 640px); min-inline-size: 0; }
.note-aside { flex: 1 1 240px; min-inline-size: 0; position: sticky; inset-block-start: 84px; }
.toc { display: flex; flex-direction: column; gap: 4px; font-size: .84rem; }
.toc a { color: var(--muted); padding: 5px 8px; border-radius: 7px; border-inline-start: 2px solid transparent; }
.toc a:hover { color: var(--text); background: var(--panel-2); text-decoration: none; }
.toc a.lvl-3 { padding-inline-start: 20px; font-size: .8rem; }
.toc a.active { color: var(--accent); border-inline-start-color: var(--accent); background: color-mix(in srgb, var(--accent) 8%, transparent); }

.markdown { line-height: 1.78; }
.markdown > :first-child { margin-block-start: 0; }
.markdown h1 { font-size: clamp(1.45rem, 2vw + .7rem, 2.1rem); letter-spacing: -.02em; line-height: 1.18; margin: 0 0 14px; }
.markdown h2 { font-size: clamp(1.12rem, 1.2vw + .8rem, 1.42rem); margin: 30px 0 10px; padding-block-start: 6px; border-block-start: 1px solid var(--border); }
.markdown h3 { font-size: 1.03rem; margin: 22px 0 8px; }
.markdown p { margin: 0 0 12px; }
.markdown ul, .markdown ol { padding-inline-start: 1.35em; margin: 0 0 14px; }
.markdown li { margin-block-end: 5px; }
.markdown li > p { margin-block-end: 6px; }
.markdown blockquote {
  margin: 14px 0;
  padding: 12px 16px;
  border-inline-start: 3px solid var(--accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  background: color-mix(in srgb, var(--accent) 7%, var(--panel-2));
  color: var(--text);
}
.markdown blockquote p:last-child { margin-block-end: 0; }
.markdown blockquote[data-callout] { border-inline-start-color: var(--accent-2); }
.markdown table {
  display: block;
  inline-size: max-content;
  max-inline-size: 100%;
  overflow-x: auto;
  border-collapse: collapse;
  margin: 14px 0;
  font-size: .88rem;
}
.markdown th, .markdown td { border: 1px solid var(--border); padding: 7px 10px; text-align: start; vertical-align: top; }
.markdown th { background: var(--panel-2); font-weight: 700; }
.markdown hr { border: 0; border-block-start: 1px solid var(--border); margin: 24px 0; }
.markdown img { max-inline-size: 100%; block-size: auto; border-radius: var(--radius-sm); border: 1px solid var(--border); background: #fff; }
.markdown details { margin: 12px 0; padding: 10px 14px; border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--panel-2); }
.markdown summary { cursor: pointer; font-weight: 650; }
.markdown .katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  padding-block: 6px;
  border-radius: 10px;
  cursor: zoom-in;
  transition: background .18s ease;
}
.markdown .katex-display:hover { background: color-mix(in srgb, var(--accent) 6%, transparent); }
.markdown .katex { font-size: 1.16em; cursor: zoom-in; }
.markdown .katex-display > .katex { font-size: 1.5em; }
.markdown .anchor-link { color: var(--faint); font-size: .7em; margin-inline-start: 6px; opacity: 0; }
.markdown h2:hover .anchor-link, .markdown h3:hover .anchor-link { opacity: 1; }

/* ------------------------------------------------------------------ questions */
.filters {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: flex-end;
  margin-block-end: var(--gap);
}
.filters .field { flex: 1 1 140px; min-inline-size: 0; }
.filters .field.search { flex: 2 1 240px; }
.question-list { display: flex; flex-direction: column; gap: 10px; }
.question-card {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  padding: 14px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  text-decoration: none;
  transition: border-color .16s ease, background .16s ease, transform .16s ease;
}
.question-card:hover { border-color: var(--border-strong); background: var(--panel-2); transform: translateY(-1px); text-decoration: none; }
.question-card .q-main { flex: 2 1 320px; min-inline-size: 0; }
.question-card .q-title { font-weight: 700; margin-block-end: 3px; }
.question-card .q-meta { color: var(--muted); font-size: .78rem; display: flex; gap: 8px; flex-wrap: wrap; }
.question-card .q-side { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.q-hero { display: flex; flex-wrap: wrap; gap: 10px 18px; align-items: flex-start; justify-content: space-between; }
.q-hero h1 { margin: 0; font-size: clamp(1.3rem, 1.8vw + .7rem, 1.9rem); letter-spacing: -.02em; }
.q-stem { font-size: clamp(1rem, .5vw + .92rem, 1.12rem); }
.answer-panel {
  margin-block-start: 16px;
  padding: clamp(14px, 2vw, 22px);
  border-radius: var(--radius);
  border: 1px solid color-mix(in srgb, var(--accent-2) 35%, var(--border));
  background: color-mix(in srgb, var(--accent-2) 6%, var(--panel-2));
}
.answer-panel h3 { color: var(--accent-2); }
.solution-block { margin-block-start: 14px; }
.solution-block details { border-radius: var(--radius-sm); border: 1px solid var(--border); background: var(--panel-2); padding: 10px 14px; }
.solution-block summary { cursor: pointer; font-weight: 650; }

/* ------------------------------------------------------------------ practice */
.practice-shell { display: flex; flex-direction: column; gap: var(--gap); }
.practice-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}
.practice-progress { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; color: var(--muted); font-size: .84rem; }
.practice-progress .bar { inline-size: clamp(120px, 26vw, 300px); }
.timer {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 7px 12px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  font-variant-numeric: tabular-nums;
  font-weight: 700;
  color: var(--text);
}
.timer.over { color: var(--danger); border-color: color-mix(in srgb, var(--danger) 45%, var(--border)); background: var(--danger-soft); }
.practice-question {
  padding: clamp(18px, 3vw, 34px);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: linear-gradient(180deg, var(--panel), color-mix(in srgb, var(--panel) 86%, var(--bg)));
  box-shadow: var(--shadow);
}
.practice-question .q-meta { display: flex; flex-wrap: wrap; gap: 8px; margin-block-end: 14px; }
.practice-question .markdown { font-size: clamp(1rem, .5vw + .94rem, 1.14rem); }
.grade-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 132px), 1fr));
  gap: 8px;
}
.grade-btn {
  display: flex;
  flex-direction: column;
  gap: 2px;
  align-items: flex-start;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--text);
  text-align: start;
  min-block-size: 54px;
}
.grade-btn small { color: var(--muted); font-size: .72rem; }
.grade-btn:hover { border-color: var(--border-strong); background: var(--panel-3); }
.grade-btn.active { border-color: color-mix(in srgb, var(--accent) 60%, var(--border)); background: color-mix(in srgb, var(--accent) 15%, var(--panel)); box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 12%, transparent); }
.grade-btn[data-grade^="wrong"].active, .grade-btn[data-grade="timeout"].active { border-color: color-mix(in srgb, var(--danger) 55%, var(--border)); background: var(--danger-soft); box-shadow: 0 0 0 3px color-mix(in srgb, var(--danger) 12%, transparent); }
.grade-btn[data-grade^="correct"].active { border-color: color-mix(in srgb, var(--ok) 55%, var(--border)); background: var(--ok-soft); box-shadow: 0 0 0 3px color-mix(in srgb, var(--ok) 12%, transparent); }
.practice-controls { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; margin-block-start: 16px; }
.practice-note { flex: 2 1 260px; min-inline-size: 0; }
.confidence { display: flex; gap: 6px; flex-wrap: wrap; }
.confidence button {
  inline-size: 40px;
  block-size: 40px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--muted);
  font-weight: 700;
}
.confidence button.active { color: var(--text); border-color: var(--accent); background: color-mix(in srgb, var(--accent) 16%, var(--panel)); }
.session-summary { text-align: center; padding: clamp(22px, 4vw, 44px); }
.session-summary .big { font-size: clamp(2.4rem, 5vw, 4rem); font-weight: 800; line-height: 1; }
.session-summary .ring { inline-size: min(100%, 340px); margin-inline: auto; }

/* ------------------------------------------------------------------ stats */
.bar-row { display: flex; align-items: center; gap: 10px; }
.bar-row .bar { flex: 1 1 auto; }
.bar-row .bar-label { flex: 0 0 64px; color: var(--muted); font-size: .78rem; }
.bar-row .bar-value { flex: 0 0 44px; text-align: end; color: var(--muted); font-size: .78rem; font-variant-numeric: tabular-nums; }
.spark { display: flex; align-items: flex-end; gap: 5px; block-size: 90px; padding-block-start: 8px; }
.spark .col { flex: 1 1 0; display: flex; flex-direction: column; justify-content: flex-end; gap: 3px; min-inline-size: 0; block-size: 100%; }
.spark .col span { display: block; inline-size: 100%; border-radius: 4px 4px 2px 2px; background: linear-gradient(180deg, var(--accent), color-mix(in srgb, var(--accent) 40%, transparent)); min-block-size: 2px; }
.spark .col small { color: var(--faint); font-size: .6rem; text-align: center; white-space: nowrap; overflow: hidden; }

.table-wrap { overflow-x: auto; border-radius: var(--radius-sm); border: 1px solid var(--border); }
table.data { inline-size: 100%; border-collapse: collapse; font-size: .84rem; min-inline-size: 560px; }
table.data th, table.data td { padding: 9px 11px; border-block-end: 1px solid var(--border); text-align: start; vertical-align: top; }
table.data th { color: var(--muted); font-size: .72rem; letter-spacing: .05em; text-transform: uppercase; background: var(--panel-2); }
table.data tr:last-child td { border-block-end: 0; }
table.data tr:hover td { background: color-mix(in srgb, var(--accent) 4%, transparent); }

/* ------------------------------------------------------------------ search */
.search-hero { display: flex; gap: 10px; flex-wrap: wrap; align-items: flex-end; }
.search-hero .field { flex: 1 1 320px; }
.result-list { display: flex; flex-direction: column; gap: 10px; }
.result {
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: 13px 14px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  text-decoration: none;
}
.result:hover { border-color: var(--border-strong); background: var(--panel-2); text-decoration: none; }
.result .r-top { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.result .r-title { font-weight: 700; }
.result .r-sub { color: var(--muted); font-size: .78rem; }
.result .r-snip { color: var(--muted); font-size: .84rem; line-height: 1.55; }

/* ------------------------------------------------------------------ modal / toast */
.modal-backdrop {
  position: fixed;
  inset: 0;
  z-index: 80;
  display: grid;
  place-items: center;
  padding: clamp(14px, 4vw, 40px);
  background: rgba(3, 7, 14, .66);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  animation: fade-in .18s ease both;
}
@keyframes fade-in { from { opacity: 0; } to { opacity: 1; } }
.modal-card {
  inline-size: min(100%, 560px);
  max-block-size: min(86dvh, 760px);
  overflow: auto;
  padding: clamp(18px, 3vw, 28px);
  border-radius: var(--radius);
  border: 1px solid var(--border-strong);
  background: var(--panel);
  box-shadow: var(--shadow);
  animation: modal-in .2s ease both;
}
.modal-card.math-zoom-modal { inline-size: min(94vw, 980px); max-block-size: min(92dvh, 920px); }
.math-zoom-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px 12px;
  margin-block-end: 12px;
}
.math-zoom-head h2 { margin: 0; }
.math-zoom-actions { display: flex; align-items: center; flex-wrap: wrap; gap: 6px; }
.math-zoom-body {
  display: flex;
  align-items: flex-start;
  overflow: auto;
  max-block-size: 66dvh;
  padding: clamp(18px, 4vw, 44px);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background:
    radial-gradient(640px 260px at 50% 0%, color-mix(in srgb, var(--accent) 8%, transparent), transparent 70%),
    var(--bg);
  cursor: grab;
  scrollbar-gutter: stable;
  overscroll-behavior: contain;
  touch-action: none;
  user-select: none;
  -webkit-user-select: none;
}
.math-zoom-body.is-dragging { cursor: grabbing; }
.math-zoom-stage {
  display: inline-block;
  flex: none;
  margin-inline: auto;
  min-inline-size: max-content;
  white-space: nowrap;
}
.math-zoom-body .katex,
.math-zoom-body .katex-display,
.math-zoom-body .katex-display > .katex {
  font-size: clamp(1.8rem, 4vw, 3rem);
  white-space: nowrap;
}
.math-zoom-body .katex-display { display: inline-block; margin: 0; overflow: visible; cursor: default; }
@keyframes modal-in { from { opacity: 0; transform: translateY(10px) scale(.98); } to { opacity: 1; transform: none; } }
.modal-card h2 { margin: 0 0 6px; font-size: 1.25rem; }
.modal-actions { display: flex; flex-wrap: wrap; gap: 8px; justify-content: flex-end; margin-block-start: 18px; }
.modal-summary { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 150px), 1fr)); gap: 8px; margin-block: 14px; }
.modal-summary .item { padding: 9px 11px; border-radius: var(--radius-xs); background: var(--panel-2); border: 1px solid var(--border); }
.modal-summary .item small { display: block; color: var(--muted); font-size: .7rem; }
.modal-summary .item strong { font-size: .92rem; }

.toast-root {
  position: fixed;
  inset-inline: 0;
  inset-block-end: max(16px, env(safe-area-inset-bottom));
  z-index: 100;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  pointer-events: none;
  padding-inline: 12px;
}
.toast {
  max-inline-size: min(92vw, 520px);
  padding: 10px 16px;
  border-radius: 999px;
  border: 1px solid var(--border-strong);
  background: var(--panel);
  color: var(--text);
  box-shadow: var(--shadow);
  font-size: .86rem;
  animation: toast-in .2s ease both;
}
.toast.ok { border-color: color-mix(in srgb, var(--ok) 45%, var(--border)); }
.toast.err { border-color: color-mix(in srgb, var(--danger) 45%, var(--border)); color: var(--danger); }
@keyframes toast-in { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }

/* ------------------------------------------------------------------ states */
.empty {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  padding: clamp(28px, 6vw, 64px) 18px;
  text-align: center;
  color: var(--muted);
}
.empty .empty-icon { font-size: 2rem; opacity: .8; }
.empty h3 { margin: 0; color: var(--text); }
.skeleton {
  border-radius: var(--radius-sm);
  background: linear-gradient(90deg, var(--panel-2) 25%, var(--panel-3) 37%, var(--panel-2) 63%);
  background-size: 400% 100%;
  animation: shimmer 1.3s ease infinite;
  min-block-size: 16px;
}
@keyframes shimmer { 0% { background-position: 100% 0; } 100% { background-position: 0 0; } }
.loading-stack { display: flex; flex-direction: column; gap: 12px; }
.loading-stack .skeleton:nth-child(2) { inline-size: 82%; }
.loading-stack .skeleton:nth-child(3) { inline-size: 64%; }

.callout {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--muted);
  font-size: .86rem;
}
.callout strong { color: var(--text); }
.callout.warn { border-color: color-mix(in srgb, var(--warn) 36%, var(--border)); background: var(--warn-soft); }
.callout.ok { border-color: color-mix(in srgb, var(--ok) 36%, var(--border)); background: var(--ok-soft); }

/* Keep touch targets comfortable without fixed breakpoints. */
button, .btn, .chip, .nav a, .icon-btn, .segmented button { min-block-size: 44px; }
.grade-btn, .kp-card, .question-card, .result { min-block-size: 44px; }