:root {
  --bg: #edf3f6;
  --card: #fffdfa;
  --card-border: #cfd9df;
  --text: #1f2f36;
  --muted: #5d6b73;
  --accent: #0b6ba8;
  --accent-soft: #d9ecf7;
  --accent-deep: #094e79;
  --success: #1d6c43;
  --success-soft: #dcf2e5;
  --error: #8e3340;
  --error-soft: #f8dfe3;
  --warning: #8b5f18;
  --shadow: 0 14px 30px rgba(24, 42, 51, 0.08);
  --radius: 18px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Avenir Next", "Segoe UI", sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at top left, rgba(217, 236, 247, 0.95), transparent 28%),
    linear-gradient(180deg, #f8fbfc 0%, var(--bg) 100%);
}

button,
input,
select {
  font: inherit;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

.app-shell {
  width: min(1120px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 1.5rem 0 3rem;
}

.card {
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.25rem;
}

.hero {
  display: grid;
  grid-template-columns: 1.7fr 1fr;
  gap: 1.25rem;
  align-items: start;
  margin-bottom: 1.25rem;
}

.eyebrow {
  margin-bottom: 0.45rem;
  text-transform: uppercase;
  letter-spacing: 0.11em;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--accent);
}

h1 {
  margin-bottom: 0.6rem;
  font-size: clamp(2rem, 4vw, 3.1rem);
  line-height: 1.02;
}

h2 {
  margin-bottom: 0.35rem;
  font-size: 1.35rem;
}

h3 {
  margin-bottom: 0.65rem;
  font-size: 1rem;
}

.intro,
.supporting-text,
.subtle,
.placeholder {
  color: var(--muted);
}

.hero-note {
  padding: 1rem 1.1rem;
  border-radius: 16px;
  border: 1px solid #c7d9e4;
  background: linear-gradient(135deg, #e5f3fb, #f7fbfe);
  color: #234352;
  font-weight: 600;
}

.controls,
.button-row,
.control-group,
.section-heading,
.study-card,
.answer-item,
.feedback-panel,
.analysis-block,
.diagram-card,
.diagram-copy,
.select-block,
.prompt-callout {
  display: flex;
}

.controls {
  justify-content: space-between;
  align-items: end;
  gap: 1rem;
  margin-bottom: 1.25rem;
}

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

.study-card {
  gap: 0.65rem;
  padding: 1rem;
  border: 1px solid #d7e1e6;
  border-radius: 16px;
  background: #fcfefd;
}

.study-list {
  margin: 0;
  padding-left: 1.15rem;
  line-height: 1.7;
}

.button-row {
  flex-wrap: wrap;
  gap: 0.75rem;
}

.control-group,
.section-heading,
.answer-item,
.feedback-panel,
.analysis-block,
.diagram-card,
.diagram-copy,
.select-block {
  flex-direction: column;
}

.control-group label,
.select-block label {
  margin-bottom: 0.4rem;
  font-weight: 700;
}

select,
button {
  border-radius: 12px;
}

select,
input {
  width: 100%;
  padding: 0.8rem 0.9rem;
  border: 1px solid #bfcbd2;
  background: #fff;
  color: var(--text);
  border-radius: 12px;
}

select:focus,
input:focus,
button:focus {
  outline: 3px solid rgba(11, 107, 168, 0.18);
  outline-offset: 2px;
}

button {
  border: 1px solid transparent;
  background: var(--accent);
  color: #fff;
  padding: 0.82rem 1.15rem;
  font-weight: 700;
  cursor: pointer;
  transition: transform 160ms ease, opacity 160ms ease, background 160ms ease;
}

button:hover {
  transform: translateY(-1px);
}

button.secondary {
  background: #e5f0f7;
  color: var(--text);
  border-color: #c8d7e0;
}

button.ghost {
  background: transparent;
  color: var(--text);
  border-color: #bdc8ce;
}

.problem-grid {
  display: grid;
  grid-template-columns: 1.02fr 0.98fr;
  gap: 1.25rem;
  margin-bottom: 1.25rem;
}

.scenario-panel,
.diagram-grid {
  min-height: 180px;
}

.scenario-panel.empty,
.diagram-grid.empty {
  display: grid;
  place-items: center;
}

.event-list,
.prompt-grid,
.analysis-grid,
.diagram-grid {
  display: grid;
  gap: 1rem;
}

.event-card,
.prompt-callout,
.analysis-block,
.answer-item,
.diagram-card {
  border: 1px solid #d7e1e6;
  border-radius: 16px;
  background: #fcfefd;
}

.event-card,
.analysis-block,
.answer-item,
.diagram-card {
  padding: 1rem;
}

.event-kicker {
  margin-bottom: 0.35rem;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
}

.event-card p:last-child,
.answer-item p:last-child,
.analysis-block p:last-child,
.diagram-copy p:last-child {
  margin-bottom: 0;
}

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

.select-block {
  gap: 0.2rem;
}

.feedback-panel {
  gap: 0.6rem;
  margin-top: 1rem;
  padding: 1rem;
  border-radius: 14px;
  border: 1px solid #d4dee5;
  background: #f8fbfd;
}

.feedback-panel.success {
  background: var(--success-soft);
  border-color: #b8dfc9;
}

.feedback-panel.warning {
  background: #faf5e8;
  border-color: #e8d7a8;
}

.feedback-panel.error {
  background: var(--error-soft);
  border-color: #e7b6bd;
}

.feedback-list {
  margin: 0;
  padding-left: 1.1rem;
}

.answer-content,
.analysis-grid {
  gap: 1rem;
}

.answer-actions {
  margin-top: 1rem;
}

.why-panel {
  margin-top: 0.9rem;
}

.why-panel p:last-child {
  margin-bottom: 0;
}

.answer-item strong {
  color: var(--accent-deep);
}

.callout {
  margin: 0;
  padding: 0.9rem 1rem;
  border-radius: 14px;
  background: var(--accent-soft);
  border: 1px solid #c0ddeb;
  color: #1d4358;
}

.diagram-grid {
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.diagram-card img {
  width: 100%;
  height: auto;
  border-radius: 12px;
  border: 1px solid #dce6ec;
  background: #f7fbfd;
}

.diagram-title {
  margin-bottom: 0.35rem;
  font-weight: 700;
}

.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 0.9rem;
}

.tag {
  padding: 0.35rem 0.7rem;
  border-radius: 999px;
  background: #ebf5fb;
  border: 1px solid #cde2ef;
  color: #24526a;
  font-size: 0.88rem;
  font-weight: 700;
}

.hidden {
  display: none;
}

@media (max-width: 860px) {
  .hero,
  .problem-grid {
    grid-template-columns: 1fr;
  }

  .controls {
    flex-direction: column;
    align-items: stretch;
  }

  .study-grid,
  .prompt-grid {
    grid-template-columns: 1fr;
  }
}