:root {
  --bg: #f8fafc;
  --surface: #ffffff;
  --surface-muted: #eef4ff;
  --text: #0f172a;
  --muted: #475569;
  --border: #cbd5e1;
  --accent: #1d4ed8;
  --accent-soft: #dbeafe;
  --success-bg: #ecfdf5;
  --success-border: #86efac;
  --info-bg: #eff6ff;
  --info-border: #93c5fd;
  --bridge-bg: #fff7ed;
  --bridge-border: #fdba74;
  --shadow: 0 12px 30px rgba(15, 23, 42, 0.08);
  --radius: 18px;
  --radius-sm: 12px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: linear-gradient(180deg, #f8fafc 0%, #f8fafc 45%, #eef4ff 100%);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP", "Hiragino Sans", "Yu Gothic UI", sans-serif;
  line-height: 1.8;
}

img {
  max-width: 100%;
  height: auto;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

code,
pre {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

.site-header {
  padding: 28px 20px 12px;
}

.page-shell {
  max-width: 1040px;
  margin: 0 auto;
  padding: 0 20px 72px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  letter-spacing: 0.02em;
  color: var(--text);
  text-decoration: none;
  margin-bottom: 10px;
}

.brand:hover {
  text-decoration: none;
}

.breadcrumbs {
  margin: 0 0 20px;
  color: var(--muted);
  font-size: 0.95rem;
}

.breadcrumbs a {
  color: inherit;
}

.page-hero {
  background: rgba(255, 255, 255, 0.94);
  border: 1px solid rgba(203, 213, 225, 0.9);
  border-radius: 26px;
  box-shadow: var(--shadow);
  padding: 30px clamp(20px, 4vw, 42px);
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--accent);
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  font-size: 0.86rem;
}

.page-title {
  margin: 0;
  font-size: clamp(1.9rem, 4vw, 3rem);
  line-height: 1.2;
}

.page-subtitle {
  margin: 10px 0 0;
  color: var(--muted);
  font-size: 1.06rem;
  max-width: 68ch;
}

.hero-badge {
  display: inline-flex;
  margin-top: 16px;
  padding: 0.45rem 0.8rem;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 700;
  font-size: 0.95rem;
}

main {
  margin-top: 24px;
}

.section-card,
.callout,
.simulator-shell {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px clamp(18px, 3vw, 30px);
  box-shadow: var(--shadow);
}

.section-card + .section-card,
.section-card + .callout,
.callout + .section-card,
.callout + .callout,
.simulator-shell + .section-card,
.section-card + .simulator-shell {
  margin-top: 22px;
}

.section-card > h2,
.callout > h2,
.simulator-shell > h2 {
  margin-top: 0;
  margin-bottom: 12px;
  font-size: clamp(1.2rem, 2.2vw, 1.6rem);
  line-height: 1.3;
}

.section-intro {
  color: var(--muted);
  margin-top: 0;
}

.callout.info {
  background: var(--info-bg);
  border-color: var(--info-border);
}

.callout.bridge {
  background: var(--bridge-bg);
  border-color: var(--bridge-border);
}

.callout.success {
  background: var(--success-bg);
  border-color: var(--success-border);
}

.glossary-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
  margin-top: 16px;
}

.glossary-card {
  background: #fbfdff;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 16px;
}

.glossary-card h3 {
  margin: 0 0 8px;
  font-size: 1.02rem;
}

.glossary-card p {
  margin: 0;
  color: var(--muted);
  font-size: 0.96rem;
}

.summary-list {
  margin: 12px 0 0;
  padding-left: 1.15rem;
}

.summary-list li + li {
  margin-top: 8px;
}

.study-steps {
  margin: 0;
  padding-left: 1.25rem;
}

.study-steps li + li {
  margin-top: 8px;
}

.diagram {
  margin: 18px 0 0;
}

.diagram img {
  display: block;
  width: 100%;
  border-radius: 18px;
  border: 1px solid var(--border);
  background: #ffffff;
}

.diagram figcaption {
  margin-top: 10px;
  color: var(--muted);
  font-size: 0.94rem;
}

.simple-table-wrap {
  overflow-x: auto;
  margin-top: 14px;
}

.simple-table {
  width: 100%;
  border-collapse: collapse;
  min-width: 560px;
}

.simple-table th,
.simple-table td {
  padding: 12px 14px;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

.simple-table th {
  text-align: left;
  background: #f8fbff;
  font-weight: 700;
}

.process-strip {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(185px, 1fr));
  gap: 14px;
  margin-top: 14px;
}

.process-card {
  border: 1px solid var(--border);
  border-radius: 16px;
  background: #fbfdff;
  padding: 16px;
}

.process-card h3 {
  margin: 0 0 6px;
  font-size: 1.02rem;
}

.process-card p {
  margin: 0;
  color: var(--muted);
  font-size: 0.96rem;
}

.chapter-grid,
.case-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 16px;
}

.chapter-card,
.case-card {
  display: block;
  background: #fbfdff;
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 18px;
  transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease;
}

.chapter-card:hover,
.case-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 16px 28px rgba(15, 23, 42, 0.10);
  border-color: #94a3b8;
  text-decoration: none;
}

.chapter-no {
  margin: 0 0 8px;
  color: var(--accent);
  font-weight: 800;
  font-size: 0.92rem;
}

.chapter-card h3,
.case-card h3 {
  margin: 0 0 8px;
  color: var(--text);
  font-size: 1.06rem;
}

.chapter-card p,
.case-card p {
  margin: 0;
  color: var(--muted);
}

.qa-list {
  display: grid;
  gap: 16px;
  margin-top: 16px;
}

.qa-card {
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 18px;
  background: #fbfdff;
}

.qa-card h3 {
  margin: 0 0 10px;
  font-size: 1.04rem;
}

.choice-list {
  margin: 12px 0 0 1.4rem;
}

.choice-list li + li {
  margin-top: 6px;
}

details {
  margin-top: 14px;
  border-top: 1px dashed var(--border);
  padding-top: 12px;
}

summary {
  cursor: pointer;
  font-weight: 700;
  color: var(--accent);
}

.definition-list {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
  margin: 0;
}

.definition-list div {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  border-bottom: 1px solid var(--border);
  padding-bottom: 8px;
}

.definition-list dt {
  font-weight: 700;
}

.definition-list dd {
  margin: 0;
  color: var(--muted);
  text-align: right;
}

.simulator-shell {
  margin-top: 22px;
}

.simulator-layout {
  display: grid;
  grid-template-columns: minmax(260px, 320px) 1fr;
  gap: 20px;
  align-items: start;
  margin-top: 18px;
}

.simulator-controls,
.simulator-results {
  display: grid;
  gap: 14px;
}

.control-group,
.metric-panel {
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 16px;
  background: #fbfdff;
}

.control-group label {
  display: block;
  font-weight: 700;
  margin-bottom: 10px;
}

.control-group input[type="range"] {
  width: 100%;
}

.control-value {
  margin: 8px 0 0;
  color: var(--muted);
  font-weight: 700;
}

.preset-group {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.preset-group button {
  appearance: none;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  padding: 0.65rem 0.9rem;
  border-radius: 999px;
  cursor: pointer;
  font-weight: 700;
}

.preset-group button:hover,
.preset-group button:focus-visible {
  border-color: var(--accent);
  color: var(--accent);
  outline: none;
}

.metric-panel h3 {
  margin-top: 0;
  margin-bottom: 12px;
  font-size: 1.04rem;
}

.meter-row + .meter-row {
  margin-top: 14px;
}

.meter-head {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 8px;
}

.meter {
  height: 12px;
  border-radius: 999px;
  background: #e2e8f0;
  overflow: hidden;
}

.meter span {
  display: block;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, #60a5fa, #1d4ed8);
}

.code-block {
  margin: 14px 0 0;
  overflow: auto;
  background: #0f172a;
  color: #e2e8f0;
  border-radius: 18px;
  padding: 18px;
  font-size: 0.92rem;
  line-height: 1.7;
}

.equation {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 12px 0 0;
  padding: 0.6rem 0.85rem;
  border-radius: 999px;
  background: #eff6ff;
  border: 1px solid #bfdbfe;
  font-size: 0.98rem;
  flex-wrap: wrap;
}

.equation code {
  font-size: 0.98rem;
}

.footer-nav {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-top: 26px;
  padding-top: 10px;
}

.nav-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 0.9rem 1rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--surface);
  font-weight: 700;
}

.page-footer {
  margin-top: 42px;
  color: var(--muted);
  font-size: 0.95rem;
}

.page-footer p {
  margin: 6px 0;
}

.term {
  position: relative;
  display: inline-block;
  border-bottom: 1px dotted var(--accent);
  cursor: help;
  color: inherit;
}

.term::after {
  content: attr(data-tip);
  position: absolute;
  left: 0;
  bottom: calc(100% + 10px);
  width: min(24rem, 70vw);
  background: #0f172a;
  color: #f8fafc;
  border-radius: 14px;
  padding: 0.8rem 0.95rem;
  font-size: 0.9rem;
  line-height: 1.55;
  box-shadow: 0 18px 36px rgba(15, 23, 42, 0.25);
  opacity: 0;
  transform: translateY(4px);
  pointer-events: none;
  transition: opacity 0.15s ease, transform 0.15s ease;
  z-index: 20;
  white-space: normal;
}

.term:hover::after,
.term:focus::after {
  opacity: 1;
  transform: translateY(0);
}

@media (max-width: 760px) {
  .page-shell {
    padding: 0 14px 60px;
  }

  .site-header {
    padding: 18px 14px 8px;
  }

  .simulator-layout {
    grid-template-columns: 1fr;
  }

  .footer-nav {
    flex-direction: column;
  }

  .nav-link {
    justify-content: center;
  }
}