:root {
  color-scheme: dark;
  --bg: #111827;
  --bg-soft: #172033;
  --panel: #1f2a44;
  --panel-strong: #263654;
  --text: #f8fafc;
  --muted: #cbd5e1;
  --soft: #e2e8f0;
  --accent: #facc15;
  --accent-strong: #f59e0b;
  --good: #7dd3fc;
  --danger: #fca5a5;
  --line: rgba(255, 255, 255, 0.16);
  --shadow: 0 24px 70px rgba(0, 0, 0, 0.34);
  --radius-lg: 28px;
  --radius-md: 20px;
  --tap-size: 58px;
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-width: 320px;
  background:
    radial-gradient(circle at top left, rgba(250, 204, 21, 0.22), transparent 34rem),
    radial-gradient(circle at 90% 20%, rgba(125, 211, 252, 0.18), transparent 28rem),
    var(--bg);
  color: var(--text);
  font-size: 19px;
  line-height: 1.6;
}

a {
  color: inherit;
}

button,
input {
  font: inherit;
}

button {
  cursor: pointer;
}

button:focus-visible,
a:focus-visible,
input:focus-visible {
  outline: 4px solid var(--accent);
  outline-offset: 4px;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: 1rem;
  z-index: 20;
  transform: translateY(-150%);
  border-radius: 999px;
  background: var(--accent);
  color: #111827;
  padding: 0.75rem 1rem;
  font-weight: 800;
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  border-bottom: 1px solid var(--line);
  background: rgba(17, 24, 39, 0.92);
  backdrop-filter: blur(18px);
}

.top-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  width: min(1120px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 0.8rem 0;
}

.brand,
.nav-actions,
.hero-actions,
.guide-controls {
  display: flex;
  align-items: center;
  gap: 0.8rem;
}

.brand {
  min-height: var(--tap-size);
  color: var(--text);
  text-decoration: none;
  font-size: clamp(1.05rem, 2vw, 1.25rem);
  font-weight: 900;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 2.8rem;
  height: 2.8rem;
  border-radius: 1rem;
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  color: #111827;
}

.nav-button,
.primary-link,
.secondary-link,
.control-button {
  min-height: var(--tap-size);
  border: 0;
  border-radius: 999px;
  padding: 0.9rem 1.2rem;
  font-weight: 900;
  text-decoration: none;
}

.nav-button,
.secondary-link,
.control-button.secondary {
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.08);
  color: var(--text);
}

.nav-button.ghost {
  color: var(--muted);
}

.save-status {
  min-height: var(--tap-size);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(125, 211, 252, 0.12);
  color: var(--soft);
  padding: 0.75rem 1rem;
  font-size: 0.95rem;
  font-weight: 900;
  white-space: nowrap;
}

.primary-link,
.control-button.primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  color: #111827;
}

main {
  width: min(1120px, calc(100% - 2rem));
  margin: 0 auto;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(280px, 0.65fr);
  gap: 1.2rem;
  align-items: stretch;
  padding: clamp(2rem, 7vw, 5.5rem) 0 1rem;
}

.hero-copy,
.hero-card,
.quick-note,
.guide-shell,
.summary-panel,
.final-checklist,
.resource-panel,
.source-note {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: rgba(31, 42, 68, 0.84);
  box-shadow: var(--shadow);
}

.hero-copy {
  padding: clamp(1.3rem, 4vw, 3rem);
}

.hero-card {
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 1.5rem;
}

.card-icon {
  display: grid;
  place-items: center;
  width: 4rem;
  height: 4rem;
  margin-bottom: 1rem;
  border-radius: 1.2rem;
  background: rgba(250, 204, 21, 0.16);
  color: var(--accent);
  font-size: 2rem;
  font-weight: 950;
}

.eyebrow {
  margin: 0 0 0.55rem;
  color: var(--accent);
  font-size: 0.9rem;
  font-weight: 950;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  overflow-wrap: anywhere;
}

h1,
h2,
h3 {
  margin: 0;
  line-height: 1.08;
}

h1 {
  max-width: 14ch;
  font-size: clamp(2.4rem, 8vw, 5.5rem);
  letter-spacing: -0.06em;
}

h2 {
  font-size: clamp(1.75rem, 4vw, 3rem);
  letter-spacing: -0.045em;
}

h3 {
  font-size: 1.35rem;
}

.hero-text {
  max-width: 62ch;
  margin: 1.4rem 0 1.7rem;
  color: var(--soft);
  font-size: clamp(1.1rem, 3vw, 1.35rem);
}

.quick-note,
.guide-shell,
.summary-panel,
.final-checklist,
.resource-panel,
.source-note {
  margin: 1rem 0;
  padding: clamp(1.1rem, 3vw, 2rem);
}

.quick-note {
  border-color: rgba(250, 204, 21, 0.38);
  background: rgba(250, 204, 21, 0.1);
}

.guide-header,
.summary-panel,
.section-heading {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
}

.step-count {
  min-width: max-content;
  margin: 0;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 0.65rem 1rem;
  color: var(--muted);
  font-weight: 900;
}

.progress-track {
  height: 1rem;
  margin: 1.2rem 0;
  overflow: hidden;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.1);
}

#progress-bar {
  display: block;
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--good), var(--accent));
  transition: width 220ms ease;
}

.step-card {
  min-height: 460px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--panel-strong);
  padding: clamp(1rem, 3vw, 2rem);
}

.step-kicker {
  color: var(--good);
  font-weight: 950;
}

.step-card p {
  color: var(--soft);
}

.big-question {
  margin: 1rem 0;
  font-size: clamp(1.5rem, 5vw, 3.2rem);
}

.simple-list {
  display: grid;
  gap: 0.75rem;
  margin: 1.2rem 0;
  padding: 0;
  list-style: none;
}

.simple-list li,
.math-line,
.note-box {
  border: 1px solid var(--line);
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.07);
  padding: 1rem;
}

.math-stack {
  display: grid;
  gap: 0.7rem;
  margin: 1rem 0;
}

.math-line {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  font-size: clamp(1.15rem, 4vw, 1.7rem);
  font-weight: 950;
}

.math-line.warning {
  border-color: rgba(252, 165, 165, 0.5);
  color: var(--danger);
}

.answer-grid {
  display: grid;
  gap: 0.8rem;
  margin: 1.2rem 0 0;
}

.answer-option,
.final-item {
  display: grid;
  grid-template-columns: 2rem 1fr;
  gap: 0.85rem;
  align-items: start;
  min-height: var(--tap-size);
  border: 1px solid var(--line);
  border-radius: 20px;
  background: rgba(255, 255, 255, 0.08);
  padding: 1rem;
}

.answer-option {
  cursor: pointer;
}

.answer-option input,
.final-item input {
  width: 1.5rem;
  height: 1.5rem;
  margin-top: 0.22rem;
  accent-color: var(--accent);
}

.answer-option span,
.final-item span {
  color: var(--soft);
  font-weight: 750;
}

.feedback {
  margin-top: 1rem;
  border-left: 6px solid var(--accent);
  border-radius: 16px;
  background: rgba(250, 204, 21, 0.12);
  padding: 1rem;
  color: var(--soft);
}

.guide-controls {
  justify-content: space-between;
  margin-top: 1rem;
}

.control-button {
  min-width: 9.5rem;
}

.summary-score {
  display: grid;
  place-items: center;
  min-width: 11rem;
  border-radius: var(--radius-md);
  background: rgba(125, 211, 252, 0.14);
  padding: 1rem;
  text-align: center;
}

.summary-score strong {
  font-size: 3.5rem;
  line-height: 1;
  color: var(--good);
}

.summary-score span {
  color: var(--muted);
  font-weight: 850;
}

.section-heading {
  margin-bottom: 1rem;
}

.section-heading p {
  max-width: 46rem;
  margin: 0;
  color: var(--muted);
}

.checklist-grid,
.resource-grid {
  display: grid;
  gap: 0.85rem;
}

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

.resource-grid article {
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.07);
  padding: 1rem;
}

.resource-grid p {
  margin: 0.45rem 0 0;
  color: var(--muted);
}

.source-note {
  color: var(--muted);
  font-size: 1rem;
}

.source-note h2 {
  color: var(--text);
  font-size: 1.6rem;
}

.site-footer {
  width: min(1120px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 2rem 0 3rem;
  color: var(--muted);
  text-align: center;
}

@media (min-width: 821px) and (max-width: 1100px) {
  :root {
    --tap-size: 56px;
  }

  body {
    font-size: 17px;
  }

  .top-nav,
  main,
  .site-footer {
    width: min(940px, calc(100% - 2.5rem));
  }

  .top-nav {
    gap: 0.7rem;
    padding: 0.55rem 0;
  }

  .brand {
    font-size: 1.08rem;
  }

  .brand-mark {
    width: 2.45rem;
    height: 2.45rem;
    border-radius: 0.85rem;
  }

  .nav-actions {
    gap: 0.55rem;
  }

  .nav-button,
  .save-status,
  .primary-link,
  .secondary-link,
  .control-button {
    padding: 0.75rem 1rem;
  }

  .hero {
    grid-template-columns: 1fr;
    padding: 1.2rem 0 0.5rem;
  }

  h1 {
    max-width: 18ch;
    font-size: clamp(2.3rem, 5.2vw, 3.8rem);
  }

  h2 {
    font-size: clamp(1.65rem, 3vw, 2.35rem);
  }

  .quick-note,
  .guide-shell,
  .summary-panel,
  .final-checklist,
  .resource-panel,
  .source-note {
    margin: 0.75rem 0;
    padding: 1.35rem;
  }

  .step-card {
    min-height: 0;
    padding: 1.35rem;
  }

  .big-question {
    margin: 0.65rem 0;
    font-size: clamp(2.15rem, 4.1vw, 2.75rem);
    line-height: 1.12;
    letter-spacing: -0.035em;
  }

  .step-card p {
    margin: 0.75rem 0;
  }

  .answer-grid {
    gap: 0.6rem;
    margin-top: 0.85rem;
  }

  .answer-option,
  .final-item {
    border-radius: 18px;
    padding: 0.82rem 0.95rem;
  }

  .feedback {
    margin-top: 0.75rem;
    padding: 0.85rem;
  }

  .progress-track {
    height: 0.8rem;
    margin: 0.9rem 0;
  }
}

@media (max-width: 820px) {
  :root {
    --tap-size: 56px;
  }

  body {
    font-size: 17px;
  }

  main,
  .top-nav,
  .site-footer {
    width: min(100% - 1rem, 760px);
  }

  .top-nav,
  .nav-actions,
  .hero,
  .hero-actions,
  .guide-header,
  .summary-panel,
  .section-heading,
  .resource-grid {
    grid-template-columns: 1fr;
  }

  .top-nav,
  .nav-actions,
  .hero-actions,
  .guide-header,
  .summary-panel,
  .section-heading {
    align-items: stretch;
  }

  .top-nav,
  .brand,
  .nav-actions,
  .hero-actions {
    flex-direction: column;
  }

  .top-nav {
    gap: 0.55rem;
    padding: 0.55rem 0;
  }

  .brand-mark {
    width: 2.45rem;
    height: 2.45rem;
    border-radius: 0.85rem;
  }

  .hero {
    padding: 0.8rem 0 0.25rem;
  }

  .quick-note,
  .guide-shell,
  .summary-panel,
  .final-checklist,
  .resource-panel,
  .source-note {
    margin: 0.65rem 0;
    padding: 1rem;
  }

  .brand,
  .nav-button,
  .save-status,
  .primary-link,
  .secondary-link {
    width: 100%;
    justify-content: center;
    text-align: center;
  }

  h1 {
    max-width: 100%;
    font-size: clamp(2rem, 9vw, 3.1rem);
  }

  h2 {
    font-size: clamp(1.45rem, 7vw, 2.15rem);
  }

  .step-card {
    min-height: auto;
    padding: 1rem;
  }

  .big-question {
    margin: 0.65rem 0;
    font-size: clamp(1.8rem, 8vw, 2.45rem);
    line-height: 1.12;
  }

  .answer-grid {
    gap: 0.65rem;
    margin-top: 0.85rem;
  }

  .answer-option,
  .final-item {
    grid-template-columns: 1.75rem 1fr;
    gap: 0.7rem;
    padding: 0.85rem;
  }

  .feedback {
    margin-top: 0.75rem;
    padding: 0.85rem;
  }

  .progress-track {
    height: 0.8rem;
    margin: 0.85rem 0;
  }

  .guide-controls {
    display: grid;
    grid-template-columns: 1fr;
  }

  .control-button {
    width: 100%;
  }
}