:root {
  --page: #f6f7f4;
  --panel: #ffffff;
  --ink: #171717;
  --muted: #555f63;
  --rule: #d9dedb;
  --teal: #0f766e;
  --blue: #1d4ed8;
  --rose: #be123c;
  --amber: #b45309;
  --green-soft: #e7f5ef;
  --blue-soft: #eaf1ff;
  --rose-soft: #fff0f3;
  --amber-soft: #fff6df;
  --shadow: 0 10px 28px rgba(17, 24, 39, 0.08);
  --sans: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --serif: Georgia, "Times New Roman", serif;
}

* {
  box-sizing: border-box;
}

html {
  font-size: 17px;
}

body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font-family: var(--sans);
  line-height: 1.55;
}

a {
  color: var(--teal);
  text-decoration: none;
  border-bottom: 1px solid transparent;
}

a:hover {
  border-bottom-color: currentColor;
}

.hero {
  border-bottom: 1px solid var(--rule);
  background: #ffffff;
}

.hero-inner,
.wrap {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
}

.hero-inner {
  padding: 44px 0 30px;
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--teal);
  font-size: 0.78rem;
  font-weight: 750;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1 {
  max-width: 780px;
  margin: 0;
  font-size: 2rem;
  line-height: 1.12;
  letter-spacing: 0;
}

.subtitle {
  max-width: 820px;
  margin: 14px 0 0;
  color: var(--muted);
  font-size: 1rem;
}

.meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 20px;
}

.pill {
  display: inline-flex;
  align-items: center;
  min-height: 34px;
  padding: 6px 10px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: #fafafa;
  color: #2d3436;
  font-size: 0.85rem;
  font-weight: 650;
}

.wrap {
  padding: 28px 0 54px;
}

.toolbar {
  position: sticky;
  top: 0;
  z-index: 5;
  margin: 0 0 22px;
  padding: 12px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.96);
  box-shadow: var(--shadow);
}

.toolbar-label {
  margin: 0 0 8px;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 750;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.segments {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

button {
  font: inherit;
}

.seg {
  min-height: 36px;
  padding: 7px 11px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: #ffffff;
  color: var(--ink);
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 700;
}

.seg[aria-pressed="true"] {
  border-color: var(--teal);
  background: var(--green-soft);
  color: #0f4f49;
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
}

.card {
  min-height: 280px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: var(--panel);
  box-shadow: 0 1px 0 rgba(17, 24, 39, 0.03);
  overflow: hidden;
}

.card-header {
  padding: 16px 16px 12px;
  border-bottom: 1px solid var(--rule);
}

.card h2 {
  margin: 0;
  font-size: 1.05rem;
  line-height: 1.28;
  letter-spacing: 0;
}

.card .tag {
  display: inline-block;
  margin-bottom: 8px;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.card-body {
  padding: 14px 16px 16px;
}

.card-body p {
  margin: 0 0 10px;
}

.card-body ul {
  margin: 8px 0 0;
  padding-left: 18px;
}

.card-body li {
  margin: 5px 0;
}

.answer {
  margin-top: 12px;
  padding: 10px;
  border-radius: 8px;
  background: #f8fafc;
  border: 1px solid #e5e7eb;
  font-size: 0.9rem;
}

.answer strong {
  display: block;
  margin-bottom: 4px;
}

.link-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 12px;
}

.link-row a {
  min-height: 30px;
  padding: 5px 8px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: #ffffff;
  font-size: 0.82rem;
  font-weight: 700;
}

.panel {
  margin-top: 24px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: #ffffff;
  box-shadow: var(--shadow);
}

.panel h2 {
  margin: 0;
  padding: 16px 18px;
  border-bottom: 1px solid var(--rule);
  font-size: 1.15rem;
}

.panel-content {
  padding: 18px;
}

.lesson-intro {
  max-width: 860px;
  margin: 0 0 18px;
  color: var(--muted);
}

.deep-lessons .panel-content {
  display: grid;
  gap: 16px;
}

.deep-block {
  padding: 18px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: #ffffff;
}

.deep-block h3 {
  margin: 0 0 10px;
  font-size: 1.08rem;
  line-height: 1.3;
}

.deep-block p {
  margin: 0 0 10px;
}

.deep-block p:last-child {
  margin-bottom: 0;
}

.why-box,
.oral-script,
.detail-steps,
.micro-example {
  margin-top: 12px;
  padding: 12px;
  border-radius: 8px;
  font-size: 0.94rem;
}

.why-box {
  border: 1px solid #c7dfd8;
  background: var(--green-soft);
}

.oral-script {
  border: 1px solid #d7dded;
  background: var(--blue-soft);
}

.detail-steps {
  border: 1px solid #ead9a7;
  background: var(--amber-soft);
}

.detail-steps ol {
  margin: 6px 0 0;
  padding-left: 22px;
}

.detail-steps li {
  margin: 4px 0;
}

.micro-example {
  border: 1px solid #f0c0cc;
  background: var(--rose-soft);
}

.why-box strong,
.oral-script strong,
.detail-steps strong,
.micro-example strong {
  display: block;
  margin-bottom: 4px;
}

.learning-loop {
  padding: 18px;
  border: 1px solid #e6d29a;
  border-radius: 8px;
  background: var(--amber-soft);
}

.learning-loop h3 {
  margin: 0 0 8px;
  font-size: 1.05rem;
}

.learning-loop ol {
  margin: 0;
  padding-left: 22px;
}

.learning-loop li {
  margin: 6px 0;
}

.algorithm-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.algo {
  min-height: 210px;
  padding: 14px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: #fcfcfc;
}

.algo h3 {
  margin: 0 0 8px;
  font-size: 1rem;
}

.algo dl {
  margin: 0;
}

.algo dt {
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.algo dd {
  margin: 2px 0 0;
}

.quiz {
  display: grid;
  gap: 12px;
}

.quiz-card {
  padding: 14px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: #fcfcfc;
}

.quiz-card p {
  margin: 0 0 10px;
  font-weight: 700;
}

.quiz-options {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.quiz-options button {
  min-height: 34px;
  padding: 6px 10px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: #ffffff;
  cursor: pointer;
}

.feedback {
  min-height: 24px;
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.9rem;
}

.feedback.ok {
  color: #047857;
}

.feedback.no {
  color: var(--rose);
}

.checklist {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.check {
  display: flex;
  gap: 8px;
  align-items: flex-start;
  padding: 10px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: #fcfcfc;
}

.check input {
  margin-top: 4px;
}

.term-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.term {
  padding: 14px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: #ffffff;
}

.term h2 {
  margin: 0 0 6px;
  padding: 0;
  border: 0;
  font-size: 1rem;
}

.term p {
  margin: 0;
}

.accent-automata {
  border-top: 4px solid var(--blue);
}

.accent-logic {
  border-top: 4px solid var(--teal);
}

.accent-mc {
  border-top: 4px solid var(--rose);
}

.accent-games {
  border-top: 4px solid var(--amber);
}

@media (max-width: 920px) {
  .grid,
  .algorithm-grid,
  .term-grid,
  .checklist {
    grid-template-columns: 1fr;
  }

  .card {
    min-height: auto;
  }
}

@media print {
  body {
    background: #ffffff;
  }

  .toolbar,
  .quiz {
    display: none;
  }

  .hero,
  .panel,
  .card,
  .algo,
  .term {
    box-shadow: none;
  }
}