:root {
  --bg: #f5f1e8;
  --paper: rgba(255, 251, 244, 0.88);
  --paper-strong: #fff8ef;
  --ink: #1d1b18;
  --muted: #655f57;
  --hub-bg: #173841;
  --hub-ink: #fdf7ee;
  --stroke: rgba(23, 56, 65, 0.14);
  --accent: #d36c43;
  --goal: #fff0d6;
  --keys: #ddf4ea;
  --means: #f9deda;
  --props: #dcebff;
  --chi: #eee2ff;
  --cheats: #ffe5d4;
  --shadow: 0 22px 60px rgba(29, 27, 24, 0.12);
  --radius-xl: 30px;
  --radius-lg: 24px;
  --radius-md: 18px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Trebuchet MS", "Avenir Next", "Segoe UI", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at 10% 10%, rgba(105, 157, 141, 0.16), transparent 28%),
    radial-gradient(circle at 90% 8%, rgba(211, 108, 67, 0.14), transparent 24%),
    radial-gradient(circle at 50% 100%, rgba(79, 110, 163, 0.08), transparent 28%),
    linear-gradient(180deg, #faf6ef 0%, var(--bg) 100%);
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(23, 56, 65, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(23, 56, 65, 0.035) 1px, transparent 1px);
  background-size: 28px 28px;
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.5), transparent 80%);
}

.page-shell {
  width: min(1440px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 1.5rem 0 3rem;
}

.hero {
  display: grid;
  grid-template-columns: 1.35fr 0.95fr;
  gap: 1.2rem;
  align-items: stretch;
  padding: 1.5rem;
  border-radius: 34px;
  background:
    radial-gradient(circle at top right, rgba(255, 255, 255, 0.14), transparent 28%),
    linear-gradient(135deg, rgba(23, 56, 65, 0.98), rgba(39, 86, 91, 0.95));
  color: var(--hub-ink);
  box-shadow: var(--shadow);
}

.hero-copy,
.hero-note {
  position: relative;
  z-index: 1;
}

.hero-note {
  padding: 1.25rem;
  border: 1px solid rgba(255, 255, 255, 0.14);
  border-radius: 26px;
  background: rgba(255, 255, 255, 0.08);
  backdrop-filter: blur(4px);
}

.eyebrow,
.note-label,
.hub-label {
  margin: 0;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  font-size: 0.74rem;
  opacity: 0.78;
}

.hero h1 {
  margin: 0.3rem 0 0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(2.4rem, 4vw, 4.4rem);
  line-height: 0.98;
}

.subtitle {
  max-width: 52rem;
  margin: 1rem 0 0;
  font-size: 1.08rem;
  line-height: 1.7;
  color: rgba(253, 247, 238, 0.92);
}

.hero-note h2 {
  margin: 0.55rem 0 0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.55rem;
  line-height: 1.2;
}

.hero-list {
  margin: 1rem 0 0;
  padding-left: 1.2rem;
  line-height: 1.6;
}

.hero-list li + li {
  margin-top: 0.45rem;
}

.solver {
  margin-top: 1.25rem;
  padding: 1.25rem;
  border-radius: 32px;
  background:
    linear-gradient(135deg, rgba(255, 248, 239, 0.96), rgba(245, 251, 248, 0.9));
  border: 1px solid rgba(29, 27, 24, 0.08);
  box-shadow: var(--shadow);
}

.solver-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
}

.solver-label {
  margin: 0;
  font-size: 0.78rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--muted);
}

.solver-head h2 {
  margin: 0.45rem 0 0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(1.8rem, 2.4vw, 2.6rem);
  line-height: 1.1;
}

.reset-button {
  padding: 0.75rem 1rem;
  border: 1px solid rgba(29, 27, 24, 0.12);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.76);
  color: var(--ink);
  font: inherit;
  cursor: pointer;
}

.solver-grid {
  display: grid;
  grid-template-columns: 1.2fr 1.2fr 1fr;
  gap: 1rem;
  margin-top: 1rem;
}

.solver-panel,
.solver-result {
  padding: 1.1rem;
  border-radius: 24px;
  background: rgba(255, 255, 255, 0.7);
  border: 1px solid rgba(29, 27, 24, 0.08);
}

.solver-panel.is-hidden {
  display: none;
}

.solver-panel h3,
.solver-result h3,
.result-box h4 {
  margin: 0;
  font-family: Georgia, "Times New Roman", serif;
}

.solver-panel h3,
.solver-result h3 {
  font-size: 1.2rem;
  line-height: 1.2;
}

.choice-group {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
  margin-top: 0.95rem;
}

.choice-button {
  padding: 0.8rem 1rem;
  border: 1px solid rgba(23, 56, 65, 0.12);
  border-radius: 16px;
  background: #fffdf8;
  color: var(--ink);
  font: inherit;
  cursor: pointer;
  transition: transform 150ms ease, border-color 150ms ease, background 150ms ease;
}

.choice-button:hover,
.choice-button:focus-visible {
  transform: translateY(-2px);
  border-color: rgba(23, 56, 65, 0.28);
  outline: none;
}

.choice-button.is-selected {
  background: #173841;
  border-color: #173841;
  color: #fdf7ee;
}

.solver-summary,
.result-box p {
  margin: 0.7rem 0 0;
  line-height: 1.58;
}

.solver-path {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 0.9rem;
}

.path-chip {
  display: inline-flex;
  align-items: center;
  padding: 0.45rem 0.75rem;
  border-radius: 999px;
  background: rgba(211, 108, 67, 0.1);
  border: 1px solid rgba(211, 108, 67, 0.16);
  font-size: 0.9rem;
}

.path-chip.is-empty {
  background: rgba(23, 56, 65, 0.05);
  border-color: rgba(23, 56, 65, 0.1);
  color: var(--muted);
}

.solver-feedback {
  margin: 0.9rem 0 0;
  color: var(--muted);
  line-height: 1.55;
}

.result-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
  margin-top: 0.9rem;
}

.result-tag {
  display: inline-flex;
  align-items: center;
  padding: 0.45rem 0.8rem;
  border-radius: 999px;
  background: rgba(23, 56, 65, 0.08);
  border: 1px solid rgba(23, 56, 65, 0.12);
  font-size: 0.92rem;
}

.result-box {
  margin-top: 0.9rem;
  padding: 0.95rem;
  border-radius: 18px;
  background: rgba(255, 250, 242, 0.88);
  border: 1px solid rgba(29, 27, 24, 0.07);
}

.decision-strip {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 1.25rem;
}

.decision-card,
.node,
.hub,
.exam-card {
  border: 1px solid rgba(29, 27, 24, 0.08);
  box-shadow: 0 14px 34px rgba(29, 27, 24, 0.08);
}

.decision-card {
  position: relative;
  overflow: hidden;
  padding: 1.2rem;
  border-radius: var(--radius-lg);
  background: var(--paper);
}

.decision-card::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  height: 5px;
  background: linear-gradient(90deg, #d36c43, #d9b458, #5a9683);
}

.decision-step {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2rem;
  height: 2rem;
  border-radius: 999px;
  background: rgba(211, 108, 67, 0.14);
  color: #8f431f;
  font-weight: 700;
}

.decision-card h2,
.node h2,
.hub h2,
.exam-card h2 {
  margin: 0.85rem 0 0;
  font-family: Georgia, "Times New Roman", serif;
  line-height: 1.15;
}

.decision-card h2 {
  font-size: 1.2rem;
}

.decision-card p {
  margin: 0.55rem 0 0;
  color: var(--muted);
  line-height: 1.55;
}

.helper-text {
  margin: 1rem 0 0;
  color: var(--muted);
  font-size: 0.96rem;
}

.formula-bank {
  margin-top: 1rem;
  padding: 1.2rem;
  border-radius: 32px;
  background: rgba(255, 255, 255, 0.62);
  border: 1px solid rgba(29, 27, 24, 0.08);
  box-shadow: var(--shadow);
}

.practice-lab {
  margin-top: 1rem;
  padding: 1.2rem;
  border-radius: 32px;
  background: linear-gradient(140deg, rgba(255, 247, 235, 0.86), rgba(237, 247, 255, 0.86));
  border: 1px solid rgba(29, 27, 24, 0.08);
  box-shadow: var(--shadow);
}

.practice-card {
  padding: 1.1rem;
  border-radius: 24px;
  background: rgba(255, 251, 244, 0.88);
  border: 1px solid rgba(29, 27, 24, 0.08);
}

.practice-card-unified {
  margin-top: 1rem;
  background: linear-gradient(145deg, rgba(255, 251, 244, 0.92), rgba(247, 252, 255, 0.92));
}

.practice-card-unified.return-highlight {
  animation: practice-return-flash 1.2s ease;
}

.practice-card-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
}

.practice-mode-switch {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
  margin-top: 1rem;
}

.practice-mode-button.is-selected {
  background: #173841;
  border-color: #173841;
  color: #fdf7ee;
}

.practice-card h3 {
  margin: 0.5rem 0 0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.3rem;
  line-height: 1.15;
}

.practice-prompt-box {
  margin-top: 1rem;
  padding: 1rem 1.05rem;
  border-radius: 20px;
  background: linear-gradient(145deg, rgba(255, 245, 232, 0.96), rgba(255, 255, 255, 0.92));
  border: 1px solid rgba(211, 108, 67, 0.2);
  box-shadow: 0 14px 28px rgba(211, 108, 67, 0.08);
}

.practice-prompt-label {
  margin: 0;
  font-size: 0.78rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: #9a5636;
}

.practice-prompt {
  margin: 0.55rem 0 0;
  font-size: 1.08rem;
  line-height: 1.72;
  color: #241f18;
  font-weight: 700;
}

.practice-options {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.7rem;
  margin-top: 1rem;
}

.practice-option {
  width: 100%;
  justify-content: flex-start;
  text-align: left;
  background: linear-gradient(145deg, rgba(255, 243, 229, 0.96), rgba(245, 250, 255, 0.96));
  border-color: rgba(79, 110, 163, 0.22);
  color: #203246;
  box-shadow: 0 10px 20px rgba(79, 110, 163, 0.08);
}

.practice-option:hover,
.practice-option:focus-visible {
  background: linear-gradient(145deg, rgba(255, 235, 214, 0.98), rgba(235, 244, 255, 0.98));
  border-color: rgba(79, 110, 163, 0.38);
}

.practice-option.is-correct {
  background: #173841;
  border-color: #173841;
  color: #fdf7ee;
}

.practice-option.is-wrong {
  background: rgba(211, 108, 67, 0.12);
  border-color: rgba(211, 108, 67, 0.4);
  color: #8f431f;
}

.practice-feedback {
  margin-top: 1rem;
  padding: 0.9rem;
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.66);
  border: 1px solid rgba(29, 27, 24, 0.08);
  line-height: 1.55;
}

.practice-feedback.is-success {
  background: rgba(221, 244, 234, 0.82);
  border-color: rgba(90, 150, 131, 0.24);
}

.practice-feedback.is-error {
  background: rgba(255, 229, 212, 0.84);
  border-color: rgba(211, 108, 67, 0.24);
}

.practice-actions,
.case-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
  margin-top: 1rem;
}

.secondary-button {
  background: rgba(23, 56, 65, 0.06);
}

.case-button[data-practice-view-related]:not(:disabled) {
  background: linear-gradient(135deg, #4f6ea3, #2f537f);
  border-color: rgba(47, 83, 127, 0.8);
  color: #f7fbff;
  box-shadow: 0 12px 24px rgba(47, 83, 127, 0.22);
}

.case-button[data-practice-view-related]:not(:disabled):hover,
.case-button[data-practice-view-related]:not(:disabled):focus-visible {
  background: linear-gradient(135deg, #5c7db4, #355b8a);
  border-color: rgba(47, 83, 127, 0.92);
  outline: none;
}

.secondary-button:disabled,
.case-button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.quiz-progress {
  margin: 0;
  color: var(--muted);
  font-size: 0.92rem;
  white-space: nowrap;
}

.quiz-score {
  margin-top: 1rem;
  padding: 0.95rem;
  border-radius: 18px;
  background: rgba(23, 56, 65, 0.08);
  border: 1px solid rgba(23, 56, 65, 0.12);
  line-height: 1.55;
}

.floating-return {
  position: fixed;
  right: 1.25rem;
  bottom: 1.25rem;
  z-index: 20;
  padding: 0.95rem 1.15rem;
  border: 1px solid rgba(23, 56, 65, 0.18);
  border-radius: 999px;
  background: linear-gradient(135deg, #173841, #28555f);
  color: #fdf7ee;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 18px 36px rgba(23, 56, 65, 0.24);
  transition: transform 150ms ease, opacity 150ms ease, box-shadow 150ms ease;
}

.floating-return:hover,
.floating-return:focus-visible {
  transform: translateY(-2px);
  box-shadow: 0 22px 42px rgba(23, 56, 65, 0.3);
  outline: none;
}

.floating-return.is-hidden {
  opacity: 0;
  pointer-events: none;
  transform: translateY(10px);
}

@keyframes practice-return-flash {
  0% {
    box-shadow: 0 0 0 rgba(211, 108, 67, 0);
    transform: translateY(0);
  }
  30% {
    box-shadow: 0 0 0 6px rgba(211, 108, 67, 0.18);
    transform: translateY(-2px);
  }
  100% {
    box-shadow: 0 0 0 rgba(211, 108, 67, 0);
    transform: translateY(0);
  }
}

.test-bank {
  margin-top: 1rem;
  padding: 1.2rem;
  border-radius: 32px;
  background: rgba(255, 252, 247, 0.7);
  border: 1px solid rgba(29, 27, 24, 0.08);
  box-shadow: var(--shadow);
}

.case-bank {
  margin-top: 1rem;
  padding: 1.2rem;
  border-radius: 32px;
  background: rgba(248, 252, 255, 0.7);
  border: 1px solid rgba(29, 27, 24, 0.08);
  box-shadow: var(--shadow);
}

.formula-bank-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
}

.formula-bank-head h2 {
  margin: 0.45rem 0 0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(1.7rem, 2.2vw, 2.4rem);
  line-height: 1.1;
}

.formula-bank-note {
  margin: 0;
  max-width: 26rem;
  color: var(--muted);
  line-height: 1.55;
}

.inline-doc-link {
  color: inherit;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 1.02em;
  font-weight: 700;
  text-decoration-thickness: 2px;
  text-underline-offset: 0.14em;
}

.inline-doc-link::before {
  content: "PDF";
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.12rem 0.38rem;
  border-radius: 999px;
  background: rgba(23, 56, 65, 0.1);
  font-size: 0.72em;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.formula-bank-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 1rem;
}

.test-bank-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 1rem;
}

.case-bank-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 1rem;
}

.formula-card {
  padding: 1rem;
  border-radius: 22px;
  background: rgba(255, 251, 244, 0.86);
  border: 1px solid rgba(29, 27, 24, 0.08);
  transition: transform 160ms ease, box-shadow 160ms ease, border-color 160ms ease;
}

.formula-card.is-highlighted {
  transform: translateY(-4px);
  border-color: rgba(23, 56, 65, 0.28);
  box-shadow: 0 18px 36px rgba(23, 56, 65, 0.16);
  background: linear-gradient(180deg, rgba(220, 244, 234, 0.96), rgba(255, 251, 244, 0.96));
}

.test-card {
  padding: 1rem;
  border-radius: 22px;
  background: rgba(255, 251, 244, 0.86);
  border: 1px solid rgba(29, 27, 24, 0.08);
}

.test-card.is-highlighted,
.case-card.is-highlighted {
  border-color: rgba(23, 56, 65, 0.26);
  box-shadow: 0 18px 36px rgba(23, 56, 65, 0.12);
  transform: translateY(-3px);
}

.case-card {
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
  padding: 1rem;
  border-radius: 22px;
  background: rgba(255, 251, 244, 0.86);
  border: 1px solid rgba(29, 27, 24, 0.08);
  transition: transform 160ms ease, box-shadow 160ms ease, border-color 160ms ease;
}

.test-card h3 {
  margin: 0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.2rem;
}

.case-card h3 {
  margin: 0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.15rem;
  line-height: 1.2;
}

.case-card p {
  margin: 0;
  line-height: 1.55;
}

.case-button {
  margin-top: auto;
  width: fit-content;
  padding: 0.75rem 1rem;
  border: 1px solid rgba(23, 56, 65, 0.14);
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.92);
  color: var(--ink);
  font: inherit;
  cursor: pointer;
}

.case-resolution {
  padding: 0.9rem;
  border-radius: 18px;
  background: rgba(23, 56, 65, 0.05);
  border: 1px solid rgba(23, 56, 65, 0.08);
}

.case-resolution.is-hidden {
  display: none;
}

.case-resolution p {
  margin: 0;
}

.case-resolution p + p {
  margin-top: 0.55rem;
}

.formula-card-label {
  margin: 0;
  font-size: 0.76rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
}

.formula-card h3 {
  margin: 0.55rem 0 0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.2rem;
}

.formula-card p {
  margin: 0.7rem 0 0;
  line-height: 1.55;
}

.math-block {
  margin-top: 0.8rem;
  padding: 0.8rem;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.72);
  overflow-x: auto;
  overflow-y: hidden;
  -webkit-overflow-scrolling: touch;
}

.math-block .katex-display {
  margin: 0.2rem 0;
  overflow-x: auto;
  overflow-y: hidden;
}

.math-block .katex {
  max-width: 100%;
}

kbd {
  padding: 0.18rem 0.45rem;
  border: 1px solid rgba(29, 27, 24, 0.18);
  border-bottom-width: 3px;
  border-radius: 8px;
  background: rgba(255, 251, 244, 0.96);
  font-family: inherit;
  font-size: 0.9rem;
}

.mindmap {
  position: relative;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  grid-template-areas:
    "hub hub hub"
    "goal keys cheats"
    "means props chi";
  gap: 1.15rem;
  margin-top: 1rem;
  padding: 1.2rem;
  border-radius: 34px;
  background:
    radial-gradient(circle at top left, rgba(255, 255, 255, 0.68), transparent 26%),
    rgba(255, 255, 255, 0.52);
  backdrop-filter: blur(6px);
  box-shadow: var(--shadow);
}

.mindmap::before {
  content: "";
  position: absolute;
  inset: 1.25rem;
  border: 2px dashed rgba(23, 56, 65, 0.08);
  border-radius: 28px;
  pointer-events: none;
}

.hub,
.node,
.exam-card {
  position: relative;
  border-radius: var(--radius-xl);
}

.hub {
  grid-area: hub;
  align-self: stretch;
  padding: 1.6rem;
  background:
    radial-gradient(circle at top right, rgba(255, 255, 255, 0.18), transparent 34%),
    linear-gradient(145deg, rgba(23, 56, 65, 0.98), rgba(27, 69, 75, 0.95));
  color: var(--hub-ink);
  z-index: 2;
  min-height: 0;
}

.hub h2 {
  font-size: clamp(1.9rem, 2.2vw, 2.7rem);
}

.hub p {
  margin: 0.9rem 0 0;
  line-height: 1.65;
  max-width: 58rem;
}

.hub-points {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  margin-top: 1.15rem;
}

.hub-points span,
.formula-chip {
  display: inline-flex;
  align-items: center;
  padding: 0.5rem 0.8rem;
  border-radius: 999px;
  font-size: 0.92rem;
}

.hub-chip {
  display: inline-flex;
  align-items: center;
  padding: 0.5rem 0.8rem;
  border-radius: 999px;
  font-size: 0.92rem;
  background: rgba(255, 255, 255, 0.11);
  border: 1px solid rgba(255, 255, 255, 0.16);
  color: var(--hub-ink);
  font: inherit;
  cursor: pointer;
  transition: transform 150ms ease, background 150ms ease, border-color 150ms ease;
}

.hub-chip:hover,
.hub-chip:focus-visible {
  transform: translateY(-2px);
  background: rgba(255, 255, 255, 0.18);
  border-color: rgba(255, 255, 255, 0.28);
  outline: none;
}

.hub-chip.is-selected {
  background: rgba(255, 255, 255, 0.11);
  border: 1px solid rgba(255, 255, 255, 0.42);
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.18);
}

.hub-reminder {
  margin-top: 1.1rem;
  padding: 0.85rem 0.95rem;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.1);
  line-height: 1.55;
  max-width: 40rem;
}

.node {
  z-index: 2;
  padding: 1.25rem;
  cursor: pointer;
  min-height: 0;
  transition:
    transform 180ms ease,
    box-shadow 180ms ease,
    opacity 180ms ease,
    border-color 180ms ease;
}

.node::before {
  content: "";
  position: absolute;
  left: 1rem;
  right: 1rem;
  top: 0.8rem;
  height: 6px;
  border-radius: 999px;
  background: rgba(29, 27, 24, 0.08);
}

.node:hover,
.node:focus-visible {
  transform: translateY(-4px);
  box-shadow: 0 20px 42px rgba(29, 27, 24, 0.12);
  border-color: rgba(29, 27, 24, 0.16);
  outline: none;
}

.node-header {
  display: flex;
  gap: 0.8rem;
  align-items: flex-start;
}

.node-number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.15rem;
  height: 2.15rem;
  border-radius: 999px;
  background: rgba(29, 27, 24, 0.08);
  font-weight: 700;
  flex: 0 0 auto;
}

.node h2 {
  font-size: 1.45rem;
}

.node-subtitle {
  margin: 0.35rem 0 0;
  color: rgba(29, 27, 24, 0.68);
  line-height: 1.45;
}

.panel-stack {
  display: grid;
  gap: 0.9rem;
  margin-top: 1rem;
}

.mini-panel,
.key-card {
  padding: 1rem;
  border: 1px solid rgba(29, 27, 24, 0.07);
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.38);
}

.mini-panel h3,
.key-card h3 {
  margin: 0;
  font-size: 1rem;
  letter-spacing: 0.01em;
}

.mini-panel p,
.key-card p,
.clean-list,
.warning-list,
.steps-list,
.quote-list {
  margin: 0.7rem 0 0;
  line-height: 1.58;
}

.callout-line {
  padding: 0.8rem 0.9rem;
  border-left: 4px solid rgba(211, 108, 67, 0.8);
  border-radius: 0 14px 14px 0;
  background: rgba(255, 255, 255, 0.44);
}

.formula-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
  margin-top: 0.8rem;
}

.formula-chip {
  background: rgba(23, 56, 65, 0.08);
  border: 1px solid rgba(23, 56, 65, 0.12);
  color: #173841;
}

.key-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.85rem;
  margin-top: 1rem;
}

.clean-list,
.warning-list,
.steps-list,
.quote-list,
.hero-list {
  padding-left: 1.2rem;
}

.clean-list li + li,
.warning-list li + li,
.steps-list li + li,
.quote-list li + li {
  margin-top: 0.5rem;
}

.warning-list li::marker {
  color: #b35b34;
}

.steps-list li::marker {
  font-weight: 700;
}

.quote-list li {
  font-style: italic;
}

.node code,
.hero-note code,
.exam-card code,
.decision-card code {
  padding: 0.12rem 0.35rem;
  border-radius: 6px;
  background: rgba(29, 27, 24, 0.07);
  font-family: "Courier New", monospace;
  font-size: 0.95em;
}

.node-goal { grid-area: goal; background: var(--goal); }
.node-keys { grid-area: keys; background: var(--keys); }
.node-means { grid-area: means; background: var(--means); }
.node-props { grid-area: props; background: var(--props); }
.node-chi { grid-area: chi; background: var(--chi); }
.node-cheats { grid-area: cheats; background: var(--cheats); }

.mindmap.is-focused .node,
.mindmap.is-focused .hub {
  opacity: 0.22;
  transform: scale(0.985);
}

.mindmap.is-focused .node.is-active {
  opacity: 1;
  transform: translateY(-7px) scale(1.01);
  border-color: rgba(23, 56, 65, 0.28);
  box-shadow: 0 28px 60px rgba(23, 56, 65, 0.18);
}

.node.is-linked {
  border-color: rgba(23, 56, 65, 0.22);
  box-shadow: 0 18px 34px rgba(23, 56, 65, 0.12);
}

.exam-grid {
  display: grid;
  grid-template-columns: 1.1fr 1.1fr 0.9fr;
  gap: 1rem;
  margin-top: 1rem;
}

.exam-card {
  padding: 1.35rem;
  background: rgba(255, 251, 244, 0.9);
}

.exam-card-quote {
  background:
    linear-gradient(140deg, rgba(255, 240, 214, 0.96), rgba(220, 235, 255, 0.96));
}

.exam-card h2 {
  font-size: 1.32rem;
}

@media (max-width: 1180px) {
  .hero {
    grid-template-columns: 1fr;
  }

  .solver-grid {
    grid-template-columns: 1fr 1fr;
  }

  .formula-bank-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .test-bank-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .case-bank-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .decision-strip,
  .exam-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .mindmap {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    grid-template-areas:
      "hub hub"
      "goal keys"
      "means props"
      "chi cheats";
  }
}

@media (max-width: 780px) {
  .page-shell {
    width: min(100% - 1rem, 100%);
    padding-top: 1rem;
  }

  .hero,
  .mindmap,
  .decision-card,
  .exam-card,
  .hub,
  .node {
    border-radius: 22px;
  }

  .decision-strip,
  .solver-grid,
  .exam-grid,
  .formula-bank-grid,
  .test-bank-grid,
  .case-bank-grid,
  .key-grid {
    grid-template-columns: 1fr;
  }

  .formula-bank-head {
    flex-direction: column;
  }

  .formula-bank,
  .formula-card,
  .math-block {
    min-width: 0;
  }

  .formula-card {
    padding: 0.9rem;
  }

  .formula-card h3 {
    font-size: 1.08rem;
  }

  .mindmap {
    grid-template-columns: 1fr;
    grid-template-areas:
      "hub"
      "goal"
      "keys"
      "means"
      "props"
      "chi"
      "cheats";
    padding: 1rem;
  }

  .mindmap::before {
    inset: 1rem;
  }

  .formula-row,
  .hub-points {
    flex-direction: column;
    align-items: flex-start;
  }

  .math-block {
    padding: 0.7rem;
  }

  .math-block .katex-display {
    font-size: 0.92rem;
  }

  .practice-card-head {
    flex-direction: column;
  }

  .practice-options {
    grid-template-columns: 1fr;
  }

  .floating-return {
    right: 0.75rem;
    left: 0.75rem;
    bottom: 0.75rem;
    text-align: center;
  }
}