:root {
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  min-height: 100%;
  background: var(--page-background);
}

body {
  min-height: 100vh;
  margin: 0;
  color: var(--ink);
  overflow-x: hidden;
}

button,
input,
select,
textarea {
  font: inherit;
}

button {
  cursor: pointer;
}

.app-shell {
  width: min(1360px, 100%);
  min-height: 100vh;
  margin: 0 auto;
  padding: 24px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  margin-bottom: 20px;
}

.topbar-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: flex-end;
  gap: 10px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: inherit;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 42px;
  height: 42px;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  color: var(--accent);
  font-size: 1.1rem;
  font-weight: 850;
  box-shadow: var(--brand-shadow);
}

.brand strong,
.brand small {
  display: block;
}

.brand strong {
  font-size: 1.05rem;
  letter-spacing: 0;
}

.brand small {
  margin-top: 2px;
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 650;
}

.mode-tabs {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 8px;
}

.mode-toggle {
  display: grid;
  width: 42px;
  height: 42px;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  color: var(--accent);
  font-size: 1.08rem;
  font-weight: 850;
  outline: none;
  transition:
    border-color 150ms ease,
    background-color 150ms ease,
    color 150ms ease,
    transform 150ms ease;
}

.mode-toggle:hover {
  border-color: var(--line-strong);
  background: var(--panel-soft);
}

.mode-toggle:focus-visible {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px var(--focus-ring);
}

.mode-icon {
  position: relative;
  grid-area: 1 / 1;
  transition:
    opacity 150ms ease,
    transform 150ms ease;
}

.mode-icon-moon {
  opacity: 0;
  transform: translateY(4px) scale(0.82);
}

:root[data-mode="dark"] .mode-icon-sun {
  opacity: 0;
  transform: translateY(-4px) scale(0.82);
}

:root[data-mode="dark"] .mode-icon-moon {
  opacity: 1;
  transform: translateY(0) scale(1);
}

.tab,
.ghost-button,
.primary-button,
.secondary-button {
  min-height: 40px;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--ink);
  font-weight: 750;
  transition:
    border-color 150ms ease,
    background-color 150ms ease,
    color 150ms ease,
    transform 150ms ease;
}

.tab {
  padding: 0 13px;
  background: var(--panel);
}

.tab.is-active {
  border-color: var(--accent-border-strong);
  background: var(--accent-soft);
  color: var(--accent);
}

.tab:hover,
.ghost-button:hover,
.secondary-button:hover {
  border-color: var(--line-strong);
  background: var(--panel-soft);
}

.primary-button:hover {
  background: var(--accent-fill-hover);
}

.workspace {
  display: grid;
  grid-template-columns: minmax(180px, 0.55fr) minmax(0, 2.1fr) minmax(220px, 0.8fr);
  gap: 16px;
  align-items: start;
}

.drill-panel,
.tools-panel {
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--panel);
  box-shadow: var(--shadow);
}

.score-rail {
  display: grid;
  gap: 12px;
  align-content: start;
}

.score-panel {
  display: grid;
  gap: 10px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--panel);
  box-shadow: var(--shadow);
}

.stat-block {
  min-height: 78px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--panel-soft);
}

.stat-block span,
.drill-count,
.answer-unit,
.range-label,
.summary-item span {
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 750;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.stat-block strong {
  display: block;
  margin-top: 8px;
  font-size: clamp(1.35rem, 3vw, 1.85rem);
  line-height: 1;
  letter-spacing: 0;
}

.ghost-button {
  width: 100%;
  padding: 0 12px;
  background: var(--panel);
}

.support-link {
  display: grid;
  gap: 4px;
  min-height: 68px;
  align-content: center;
  padding: 12px;
  border: 1px solid var(--accent-border-soft);
  border-radius: 10px;
  background: var(--accent-soft);
  color: inherit;
  text-decoration: none;
  transition:
    border-color 150ms ease,
    background-color 150ms ease,
    transform 150ms ease;
}

.support-link:hover {
  border-color: var(--accent-border-strong);
  background: var(--accent-fill);
  transform: translateY(-1px);
}

.support-link:focus-visible {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 4px var(--focus-ring);
}

.support-link span {
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.support-link strong {
  color: var(--ink);
  font-size: 0.98rem;
  line-height: 1.15;
}

.summary-support {
  width: min(280px, 100%);
  margin-top: 16px;
}

.drill-panel {
  padding: clamp(18px, 3vw, 32px);
}

.drill-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.chip {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  padding: 0 10px;
  border: 1px solid var(--accent-border-soft);
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.chip.muted {
  border-color: var(--line);
  background: var(--panel-soft);
  color: var(--muted);
}

.drill-count {
  margin-left: auto;
}

h1 {
  max-width: 920px;
  margin: 20px 0 10px;
  font-size: clamp(2rem, 4.2vw, 3.9rem);
  line-height: 1;
  letter-spacing: 0;
}

.question-copy {
  max-width: 780px;
  margin: 0;
  color: var(--muted);
  font-size: clamp(1rem, 2vw, 1.12rem);
  font-weight: 560;
  line-height: 1.55;
}

.facts-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 10px;
  margin: 24px 0;
}

.fact {
  min-height: 82px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--panel-soft);
}

.fact span {
  display: block;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 760;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.fact strong {
  display: block;
  margin-top: 8px;
  font-size: clamp(1.1rem, 2vw, 1.45rem);
  line-height: 1.05;
}

.answer-form {
  margin-top: 6px;
}

.answer-list {
  display: grid;
  gap: 10px;
}

.answer-row {
  display: grid;
  grid-template-columns: minmax(150px, 1fr) minmax(150px, 220px) auto;
  gap: 10px;
  align-items: center;
  min-height: 72px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--panel);
}

.answer-row label {
  font-weight: 750;
}

.answer-row input,
.answer-row select {
  width: 100%;
  height: 44px;
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  padding: 0 12px;
  background: var(--field);
  color: var(--ink);
  font-size: 1.05rem;
  font-weight: 750;
  outline: none;
}

.answer-row select {
  min-width: 118px;
  font-weight: 750;
}

.answer-row select:invalid {
  color: var(--muted);
}

.answer-row input:focus,
.answer-row select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px var(--focus-ring);
}

.answer-unit {
  min-width: 74px;
  text-align: right;
}

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 14px;
}

.primary-button,
.secondary-button {
  padding: 0 18px;
}

.primary-button {
  border-color: var(--accent);
  background: var(--accent-fill);
  color: var(--ink);
}

.secondary-button {
  background: var(--panel);
}

.compact-button {
  min-height: 34px;
  padding: 0 12px;
  font-size: 0.86rem;
}

button:disabled,
button:disabled:hover {
  cursor: not-allowed;
  opacity: 0.58;
  transform: none;
}

.scratch-panel {
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--panel-soft);
}

.scratch-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 10px;
}

.scratch-head h2 {
  margin: 0;
  color: var(--muted);
  font-size: 0.78rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.scratch-panel textarea {
  display: block;
  width: 100%;
  min-height: 340px;
  resize: vertical;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
  background: var(--field);
  color: var(--ink);
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  font-size: 0.94rem;
  line-height: 1.55;
  outline: none;
}

.scratch-panel textarea:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px var(--focus-ring);
}

.feedback-panel {
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.feedback-head {
  display: flex;
  align-items: center;
  gap: 12px;
}

.feedback-head p {
  margin: 0;
  color: var(--muted);
  font-weight: 650;
}

.result-badge {
  display: inline-flex;
  align-items: center;
  min-height: 36px;
  padding: 0 12px;
  border-radius: 999px;
  background: var(--good-soft);
  color: var(--good);
  font-size: 0.78rem;
  font-weight: 850;
  text-transform: uppercase;
}

.result-badge.good {
  background: var(--accent-soft);
  color: var(--accent);
}

.result-badge.not-quite {
  background: var(--miss-soft);
  color: var(--miss);
}

.breakdown,
.review-list {
  display: grid;
  gap: 10px;
  margin-top: 14px;
}

.breakdown-row,
.review-row {
  display: grid;
  grid-template-columns: minmax(150px, 1fr) minmax(170px, 0.8fr);
  gap: 12px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--panel-soft);
}

.breakdown-row strong,
.review-row strong {
  display: block;
  font-size: 1rem;
}

.breakdown-row p,
.review-row p {
  margin: 6px 0 0;
  color: var(--muted);
  font-weight: 560;
  line-height: 1.45;
}

.solution-steps {
  margin-top: 12px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
}

.solution-steps span {
  display: block;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.solution-steps ol {
  margin: 8px 0 0;
  padding-left: 22px;
}

.solution-steps li {
  margin-top: 6px;
  color: var(--ink);
  font-weight: 620;
  line-height: 1.45;
}

.meter {
  align-self: center;
}

.meter-track {
  height: 10px;
  overflow: hidden;
  border-radius: 999px;
  background: var(--meter-track);
}

.meter-fill {
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: var(--good);
  transition: width 500ms ease;
}

.meter-fill.good {
  background: var(--accent);
}

.meter-fill.not-quite {
  background: var(--miss);
}

.range-label {
  display: block;
  margin-top: 8px;
  text-align: right;
}

.set-summary h1 {
  margin-top: 18px;
}

.summary-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  margin-top: 24px;
}

.summary-item {
  min-height: 92px;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--panel-soft);
}

.summary-item strong {
  display: block;
  margin-top: 8px;
  font-size: clamp(1.35rem, 3vw, 2rem);
  line-height: 1;
}

.review-row {
  grid-template-columns: minmax(180px, 1fr) auto;
}

.review-grade {
  align-self: center;
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 750;
}

.tools-panel {
  display: grid;
  gap: 12px;
  padding: 16px;
}

.constants-panel {
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--panel-soft);
}

.constants-panel summary {
  min-height: 42px;
  padding: 12px;
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 780;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  cursor: pointer;
}

.constants-panel dl {
  display: grid;
  gap: 10px;
  margin: 0;
  padding: 0 12px 12px;
}

.constants-panel dl div {
  display: grid;
  grid-template-columns: minmax(70px, 0.7fr) minmax(90px, 1fr);
  gap: 10px;
  align-items: center;
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--panel-soft);
}

.constants-panel dt,
.constants-panel dd {
  margin: 0;
  font-weight: 720;
}

.constants-panel dt {
  color: var(--muted);
  font-size: 0.74rem;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.constants-panel dd {
  text-align: right;
}

@media (max-width: 1100px) {
  .workspace {
    grid-template-columns: 1fr 2fr;
  }

  .tools-panel {
    grid-column: 1 / -1;
  }

  .constants-panel dl {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .scratch-panel textarea {
    min-height: 220px;
  }
}

@media (max-width: 760px) {
  .app-shell {
    padding: 14px;
  }

  .topbar {
    display: block;
  }

  .topbar-actions {
    justify-content: flex-start;
    margin-top: 16px;
  }

  .mode-tabs {
    justify-content: flex-start;
  }

  .workspace {
    display: flex;
    flex-direction: column;
  }

  .drill-panel {
    order: 1;
  }

  .tools-panel {
    order: 2;
    width: 100%;
    margin-top: 14px;
  }

  .score-rail {
    order: 3;
    width: 100%;
    margin-top: 14px;
  }

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

  .ghost-button {
    grid-column: 1 / -1;
  }

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

  .answer-row,
  .breakdown-row,
  .review-row {
    grid-template-columns: 1fr;
  }

  .answer-unit,
  .range-label,
  .review-grade {
    text-align: left;
  }

  .constants-panel dl {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 470px) {
  .facts-grid,
  .score-panel,
  .summary-grid {
    grid-template-columns: 1fr;
  }

  .controls button {
    width: 100%;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 1ms !important;
    animation-iteration-count: 1 !important;
    scroll-behavior: auto !important;
    transition-duration: 1ms !important;
  }
}