:root {
  color-scheme: light;
  --bg: #f6f7f3;
  --surface: #ffffff;
  --ink: #20231f;
  --muted: #646b61;
  --line: #d9ded4;
  --accent: #197278;
  --accent-strong: #12545a;
  --warm: #c44536;
  --soft: #e8f1ee;
  --shadow: 0 18px 44px rgba(28, 43, 34, 0.14);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic", "YuGothic", "Noto Sans JP", sans-serif;
  line-height: 1.65;
}

button,
input,
select {
  font: inherit;
}

button {
  min-height: 44px;
  border: 1px solid var(--accent);
  border-radius: 8px;
  background: var(--accent);
  color: #fff;
  cursor: pointer;
  font-weight: 700;
  transition: transform 160ms ease, background 160ms ease, border-color 160ms ease;
}

button:hover {
  background: var(--accent-strong);
  border-color: var(--accent-strong);
}

button:active {
  transform: translateY(1px);
}

main,
.topbar,
footer {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 36px 0 20px;
}

.eyebrow {
  margin: 0 0 4px;
  color: var(--warm);
  font-size: 0.84rem;
  font-weight: 800;
  letter-spacing: 0;
}

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

h1 {
  margin-bottom: 0;
  font-size: clamp(1.9rem, 4vw, 3rem);
  line-height: 1.18;
  letter-spacing: 0;
}

.score {
  display: grid;
  place-items: center;
  min-width: 92px;
  min-height: 72px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--accent-strong);
  font-size: 1.35rem;
  font-weight: 800;
  box-shadow: 0 8px 22px rgba(28, 43, 34, 0.08);
}

.controls {
  display: grid;
  grid-template-columns: minmax(240px, 1fr) minmax(170px, 240px) auto;
  gap: 12px;
  align-items: end;
  margin: 12px 0 22px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
}

.search,
.select {
  display: grid;
  gap: 6px;
  color: var(--muted);
  font-size: 0.86rem;
  font-weight: 700;
}

input,
select {
  width: 100%;
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--ink);
  padding: 0 12px;
  outline: none;
}

input:focus,
select:focus,
.flashcard:focus-visible {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px rgba(25, 114, 120, 0.16);
}

.buttonRow,
.cardNav {
  display: grid;
  grid-auto-flow: column;
  gap: 10px;
}

.buttonRow button,
.cardNav button:first-child,
.cardNav button:last-child {
  background: #fff;
  color: var(--accent-strong);
}

.buttonRow button:hover,
.cardNav button:first-child:hover,
.cardNav button:last-child:hover {
  background: var(--soft);
}

.studyPanel {
  display: grid;
  gap: 16px;
  margin-bottom: 34px;
}

.categoryOverview {
  margin: 0 0 22px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
}

.categoryGrid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
  gap: 10px;
}

.categoryChip {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  min-height: 46px;
  border-color: var(--line);
  background: #fff;
  color: var(--ink);
  padding: 9px 11px;
  text-align: left;
}

.categoryChip:hover {
  border-color: var(--accent);
  background: var(--soft);
}

.categoryChip.isActive {
  border-color: var(--accent);
  background: var(--accent);
  color: #fff;
}

.categoryName {
  overflow-wrap: anywhere;
  line-height: 1.3;
}

.categoryCount {
  flex: 0 0 auto;
  min-width: 2.2em;
  border-radius: 999px;
  background: var(--soft);
  color: var(--accent-strong);
  padding: 2px 8px;
  text-align: center;
  font-size: 0.82rem;
  font-weight: 800;
}

.categoryChip.isActive .categoryCount {
  background: #fff;
}

.flashcard {
  position: relative;
  min-height: 360px;
  border: 0;
  border-radius: 8px;
  cursor: pointer;
  perspective: 1200px;
  outline: none;
}

.cardFace {
  position: absolute;
  inset: 0;
  display: grid;
  align-content: center;
  gap: 16px;
  padding: clamp(24px, 5vw, 54px);
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  box-shadow: var(--shadow);
  backface-visibility: hidden;
  transform-style: preserve-3d;
  transition: transform 260ms ease;
}

.cardFront {
  border-top: 8px solid var(--accent);
}

.cardBack {
  border-top: 8px solid var(--warm);
  transform: rotateY(180deg);
}

.flashcard.isFlipped .cardFront {
  transform: rotateY(180deg);
}

.flashcard.isFlipped .cardBack {
  transform: rotateY(360deg);
}

.cardLabel {
  margin-bottom: 0;
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 800;
}

#questionText {
  margin: 0;
  font-size: clamp(1.45rem, 3.3vw, 2.45rem);
  line-height: 1.35;
  letter-spacing: 0;
}

#answerText {
  margin: 0;
  font-size: clamp(1.05rem, 2.3vw, 1.45rem);
}

.categoryTag {
  justify-self: start;
  margin: 0;
  padding: 6px 10px;
  border-radius: 8px;
  background: var(--soft);
  color: var(--accent-strong);
  font-size: 0.9rem;
  font-weight: 800;
}

.cardNav {
  grid-template-columns: 1fr 1.3fr 1fr;
}

.sectionHeader {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 12px;
}

.sectionHeader h2 {
  margin: 0;
  font-size: 1.25rem;
}

.sectionHeader p {
  margin: 0;
  color: var(--muted);
  font-size: 0.92rem;
}

.listGrid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 12px;
}

.miniCard {
  min-height: 132px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  padding: 14px;
  text-align: left;
  color: var(--ink);
}

.miniCard:hover {
  border-color: var(--accent);
  background: var(--soft);
}

.miniCard.isActive {
  border-color: var(--warm);
  box-shadow: inset 0 0 0 2px rgba(196, 69, 54, 0.18);
}

.miniMeta {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 8px;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 800;
}

.miniQuestion {
  margin: 0;
  font-weight: 800;
  line-height: 1.5;
}

footer {
  padding: 32px 0 44px;
  color: var(--muted);
  font-size: 0.88rem;
}

footer p {
  margin-bottom: 0;
}

@media (max-width: 760px) {
  main,
  .topbar,
  footer {
    width: min(100% - 24px, 1120px);
  }

  .topbar {
    align-items: start;
    padding-top: 24px;
  }

  .score {
    min-width: 72px;
    min-height: 58px;
    font-size: 1rem;
  }

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

  .buttonRow {
    grid-auto-flow: row;
    grid-template-columns: 1fr 1fr;
  }

  .categoryGrid {
    grid-template-columns: 1fr 1fr;
  }

  .flashcard {
    min-height: 420px;
  }

  .cardNav {
    grid-auto-flow: row;
    grid-template-columns: 1fr;
  }

  .sectionHeader {
    align-items: start;
    flex-direction: column;
    gap: 4px;
  }
}

@media (max-width: 430px) {
  .categoryGrid {
    grid-template-columns: 1fr;
  }
}