:root {
  --ink: #172026;
  --muted: #60707c;
  --line: #d8e0e5;
  --panel: #ffffff;
  --soft: #f4f7f8;
  --accent: #0f766e;
  --accent-dark: #0b4f4a;
  --gold: #d08b16;
  --blue: #245ea8;
  --danger: #b42318;
  --ok: #177245;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  color: var(--ink);
  font-family: "Yu Gothic UI", "Meiryo", system-ui, sans-serif;
  background: linear-gradient(180deg, #eef4f5 0%, #f8fafb 42%, #eef2f3 100%);
}

button,
input {
  font: inherit;
}

.app-shell {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 320px minmax(0, 1fr);
}

.side {
  position: sticky;
  top: 0;
  height: 100vh;
  display: flex;
  flex-direction: column;
  gap: 22px;
  padding: 24px;
  background: #fbfcfc;
  border-right: 1px solid var(--line);
  overflow-y: auto;
}

.brand {
  display: flex;
  gap: 14px;
  align-items: center;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  color: white;
  font-weight: 800;
  background: var(--accent-dark);
  border-radius: 8px;
}

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

h1 {
  font-size: 18px;
}

.brand p,
.lesson-lead,
#lessonLead,
.memory-hook,
#practicePrompt,
#practiceHint {
  color: var(--muted);
  line-height: 1.8;
}

.lesson-nav {
  display: grid;
  gap: 8px;
}

.lesson-button {
  width: 100%;
  border: 1px solid transparent;
  background: transparent;
  border-radius: 8px;
  padding: 12px;
  text-align: left;
  color: var(--muted);
  cursor: pointer;
}

.lesson-button strong {
  display: block;
  color: var(--ink);
  margin-bottom: 4px;
}

.lesson-button.active,
.lesson-button:hover {
  background: #e8f3f1;
  border-color: #b9d8d4;
}

.lesson-button.done strong::after {
  content: " 完了";
  color: var(--ok);
  font-size: 12px;
  font-weight: 700;
}

.progress-panel,
.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 12px 28px rgba(17, 28, 36, 0.06);
}

.progress-panel {
  padding: 16px;
  margin-top: auto;
}

.meter {
  height: 8px;
  margin: 14px 0;
  background: #e5ecef;
  border-radius: 999px;
  overflow: hidden;
}

.meter span {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--accent), var(--gold));
}

main {
  padding: 32px;
  min-width: 0;
}

.lesson-hero {
  min-height: 270px;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(300px, 520px);
  gap: 24px;
  align-items: center;
  padding: 34px;
  background: #10272c;
  color: white;
  border-radius: 8px;
  overflow: hidden;
}

.lesson-hero h2 {
  font-size: clamp(28px, 3.2vw, 42px);
  line-height: 1.15;
  margin: 8px 0 16px;
}

.lesson-hero p {
  max-width: 720px;
  color: #d6e4e5;
}

.wave-visual {
  min-height: 220px;
  background: #0b1a1e;
  border: 1px solid rgba(255, 255, 255, 0.14);
  border-radius: 8px;
}

canvas {
  display: block;
  width: 100%;
  height: 100%;
}

.toolbar {
  display: flex;
  gap: 8px;
  margin: 22px 0;
  overflow-x: auto;
}

.tab,
.ghost-button,
.primary-button,
.icon-button {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: white;
  color: var(--ink);
  cursor: pointer;
}

.tab {
  min-width: 116px;
  padding: 10px 14px;
}

.tab.active {
  background: var(--accent);
  color: white;
  border-color: var(--accent);
}

.ghost-button {
  padding: 10px 12px;
}

.primary-button {
  padding: 12px 16px;
  color: white;
  background: var(--accent);
  border-color: var(--accent);
}

.icon-button {
  width: 38px;
  height: 38px;
  color: white;
  background: var(--accent);
  border-color: var(--accent);
}

.view {
  display: none;
}

.view.active {
  display: block;
}

.content-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(280px, 0.8fr);
  gap: 18px;
}

.panel {
  padding: 22px;
}

.compact {
  min-height: 180px;
}

.panel-header {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: center;
  margin-bottom: 14px;
}

.eyebrow {
  color: var(--accent-dark);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

.point-list {
  display: grid;
  gap: 12px;
  padding: 0;
  margin: 0;
  list-style: none;
}

.point-list li {
  padding-left: 18px;
  border-left: 4px solid #b9d8d4;
  line-height: 1.8;
}

.formula-box {
  display: grid;
  gap: 10px;
  margin-top: 12px;
}

.formula {
  padding: 12px;
  background: var(--soft);
  border-radius: 8px;
  font-weight: 700;
  line-height: 1.7;
}

.cards-toolbar {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 14px;
  margin-bottom: 16px;
}

.flashcard {
  width: min(760px, 100%);
  min-height: 320px;
  display: grid;
  gap: 18px;
  align-content: center;
  margin: 0 auto;
  padding: 34px;
  text-align: center;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: white;
  box-shadow: 0 16px 32px rgba(17, 28, 36, 0.08);
}

.flashcard strong {
  font-size: clamp(28px, 5vw, 54px);
}

.flashcard span:last-child {
  color: var(--muted);
  line-height: 1.8;
}

.input-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px;
  margin: 18px 0;
}

.field {
  display: grid;
  gap: 7px;
}

.field label {
  color: var(--muted);
  font-size: 14px;
}

.field input {
  width: 100%;
  padding: 11px 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
}

.result {
  min-height: 30px;
  margin-top: 14px;
  color: var(--accent-dark);
  font-weight: 700;
  line-height: 1.7;
}

.quiz-panel {
  max-width: 880px;
}

.choice-list {
  display: grid;
  gap: 10px;
  margin: 20px 0;
}

.choice {
  width: 100%;
  padding: 13px 14px;
  text-align: left;
  background: var(--soft);
  border: 1px solid var(--line);
  border-radius: 8px;
  cursor: pointer;
}

.choice.correct {
  border-color: #9bd5b5;
  background: #e8f8ef;
}

.choice.wrong {
  border-color: #f4aca5;
  background: #fff0ee;
}

@media (max-width: 920px) {
  .app-shell {
    grid-template-columns: 1fr;
  }

  .side {
    position: static;
    height: auto;
  }

  main {
    padding: 18px;
  }

  .lesson-hero,
  .content-grid {
    grid-template-columns: 1fr;
  }

  .lesson-hero {
    padding: 24px;
  }
}

@media (max-width: 560px) {
  .side {
    padding: 16px;
  }

  .lesson-hero {
    min-height: auto;
  }

  .wave-visual {
    min-height: 170px;
  }
}