:root {
  --bg: #080809;
  --bg-elev: #111214;
  --bg-soft: #17181b;
  --border: #272a30;
  --text: #f4f4f7;
  --muted: #a0a3ab;
  --accent: #ffd54a;
  --accent-soft: rgba(255, 213, 74, 0.14);
  --accent-strong: rgba(255, 213, 74, 0.24);
  --shadow: 0 14px 40px rgba(0, 0, 0, 0.35);
  --radius: 18px;
  --radius-sm: 14px;
  --font: "Inter", "Segoe UI", system-ui, -apple-system, sans-serif;
}
* { box-sizing: border-box; }
html { scroll-behavior: auto; }
body {
  margin: 0;
  min-width: 320px;
  background:
    radial-gradient(circle at top, rgba(255, 213, 74, 0.06), transparent 28%),
    var(--bg);
  color: var(--text);
  font: 400 clamp(15px, 2.35vw, 17px)/1.55 var(--font);
}
a { color: inherit; }
button, input, textarea, select { font: inherit; }
.page {
  width: min(100%, 1480px);
  margin: 0 auto;
  padding: clamp(12px, 2vw, 28px);
  overflow-x: clip;
}
.hero {
  display: grid;
  gap: 14px;
  padding: clamp(16px, 2.2vw, 28px);
  border: 1px solid var(--border);
  border-radius: calc(var(--radius) + 4px);
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.02), rgba(255, 255, 255, 0.01));
  box-shadow: var(--shadow);
}
.hero-links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}
.hero-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 42px;
  padding: 0 14px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--bg-soft);
  color: var(--text);
  text-decoration: none;
  transition: border-color 0.16s ease, color 0.16s ease, background 0.16s ease;
}
.hero-link:hover,
.hero-link:focus-visible {
  border-color: var(--accent);
  color: var(--accent);
  outline: none;
}
.hero h1,
.task-header h1 {
  margin: 0;
  font-size: clamp(1.55rem, 3.8vw, 2.6rem);
  line-height: 1.08;
  letter-spacing: -0.03em;
}
.hero p,
.task-header p,
.task-meta,
.formula-code,
.formula-vars,
.task-empty,
.footer-note {
  margin: 0;
  color: var(--muted);
}
.hero strong,
.task-num,
.formula-code strong,
.formula-vars strong {
  color: var(--accent);
}
.task-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
  margin-top: 14px;
}
.task-link {
  display: grid;
  gap: 8px;
  min-height: 118px;
  padding: 14px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: var(--bg-elev);
  text-decoration: none;
  transition: transform 0.16s ease, border-color 0.16s ease, background 0.16s ease;
}
.task-link:hover,
.task-link:focus-visible {
  transform: translateY(-2px);
  border-color: var(--accent);
  background: var(--bg-soft);
  outline: none;
}
.task-link-num {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--accent);
}
.task-link-text {
  font-size: 0.92rem;
  line-height: 1.35;
}
.task-shell {
  display: grid;
  gap: 14px;
  overflow-x: clip;
}
.task-header {
  display: grid;
  gap: 10px;
  padding: clamp(16px, 2vw, 26px);
  border: 1px solid var(--border);
  border-radius: calc(var(--radius) + 4px);
  background: var(--bg-elev);
  box-shadow: var(--shadow);
}
.task-chip,
.formula-jump {
  border: 1px solid var(--border);
  background: var(--bg-soft);
  color: var(--text);
  border-radius: 999px;
}
.task-chip {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 40px;
  padding: 0 14px;
  text-decoration: none;
  transition: border-color 0.16s ease, color 0.16s ease, background 0.16s ease;
}
.task-chip:hover,
.task-chip:focus-visible,
.formula-jump:hover,
.formula-jump:focus-visible {
  border-color: var(--accent);
  color: var(--accent);
  outline: none;
}
.formula-summary {
  display: grid;
  gap: 12px;
}
.section-title {
  margin: 0;
  font-size: 1.02rem;
  font-weight: 650;
  letter-spacing: -0.01em;
}
.formula-grid {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-start;
  gap: 10px;
}
.formula-jump {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: fit-content;
  max-width: 100%;
  min-height: 0;
  padding: 15px 21px;
  text-decoration: none;
  background: var(--bg-elev);
  border-radius: 4px;
  box-shadow: 0 10px 26px rgba(0, 0, 0, 0.16);
  overflow: hidden;
}
.formula-jump .math,
.formula-card .math {
  display: block;
  width: auto;
  max-width: 100%;
  min-width: 0;
}
.formula-jump .math {
  overflow-wrap: anywhere;
}
.formula-jump .katex-display,
.formula-card .katex-display {
  margin: 0;
  max-width: 100%;
  overflow-x: hidden;
  overflow-y: hidden;
  text-align: center;
}
.formula-jump .katex,
.formula-card .katex {
  font-size: clamp(0.95em, 2.4vw, 1.08em);
}
.formula-jump .katex {
  font-size: clamp(1.425em, 3.6vw, 1.62em);
}
.formula-jump .katex,
.formula-jump .katex-display > .katex {
  max-width: 100%;
}
.formula-jump .katex .base {
  white-space: nowrap;
}
.formula-jump.is-wrap-text {
  justify-content: flex-start;
  text-align: left;
}
.formula-jump.is-wrap-text .math {
  width: 100%;
}
.formula-jump.is-wrap-text .katex-display,
.formula-jump.is-wrap-text .katex-display > .katex,
.formula-jump.is-wrap-text .katex-html,
.formula-jump.is-wrap-text .mord.text,
.formula-jump.is-wrap-text .mord .mtext,
.formula-jump.is-wrap-text .katex .base {
  white-space: normal;
}
.formula-list {
  display: grid;
  gap: 12px;
}
.formula-card {
  scroll-margin-top: 20px;
  display: grid;
  gap: 12px;
  padding: 14px;
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  border-radius: var(--radius);
  background: var(--bg-elev);
}
.formula-card h3 {
  margin: 0;
  font-size: 1rem;
  line-height: 1.3;
}
.formula-card .formula-code {
  font-size: 0.82rem;
}
.formula-vars {
  display: grid;
  gap: 8px;
  padding: 0;
  list-style: none;
}
.formula-vars li {
  padding-left: 10px;
  border-left: 2px solid var(--accent-soft);
}
.sym-math {
  display: inline-block;
  margin-right: 0.2em;
  vertical-align: text-bottom;
}
.sym-math .katex {
  color: var(--accent);
}
.fab,
.back-fab {
  position: fixed;
  z-index: 30;
  bottom: max(12px, env(safe-area-inset-bottom, 0px) + 12px);
  width: 52px;
  height: 52px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: rgba(17, 18, 20, 0.94);
  color: var(--text);
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow);
  transition: border-color 0.16s ease, color 0.16s ease, transform 0.16s ease;
}
.fab:hover,
.fab:focus-visible,
.back-fab:hover,
.back-fab:focus-visible {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-2px);
  outline: none;
}
.fab { right: max(12px, env(safe-area-inset-right, 0px) + 12px); }
.back-fab { left: max(12px, env(safe-area-inset-left, 0px) + 12px); }
.footer-note {
  padding: 10px 0 76px;
  font-size: 0.84rem;
}
.task-empty {
  padding: 18px;
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.02);
}
@media (max-width: 1100px) {
  .task-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}
@media (max-width: 780px) {
  .page { padding: 10px; }
  .task-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 520px) {
  .task-grid { grid-template-columns: 1fr; }
  .task-link { min-height: 98px; }
  .formula-jump { max-width: 100%; }
  .formula-jump .katex { font-size: clamp(1.32em, 7.5vw, 1.5em); }
  .formula-card .katex { font-size: clamp(0.88em, 5vw, 1em); }
}