:root {
  color-scheme: light;
  --ink: #17201c;
  --muted: #66706a;
  --paper: #fbfaf7;
  --panel: #ffffff;
  --line: #ddd9d0;
  --teal: #0f766e;
  --teal-dark: #115e59;
  --coral: #bd4b38;
  --gold: #b88918;
  --mint: #dff3ea;
  --cream: #f5efe2;
  --shadow: 0 18px 50px rgba(23, 32, 28, 0.12);
}

* {
  box-sizing: border-box;
}

html,
body {
  min-height: 100%;
}

body {
  margin: 0;
  background: linear-gradient(180deg, #f6f4ef 0%, #edf3ef 100%);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

button,
select {
  font: inherit;
}

button {
  cursor: pointer;
}

.shell {
  width: min(1440px, 100%);
  min-height: 100vh;
  margin: 0 auto;
  padding: 24px;
}

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

.eyebrow {
  margin: 0 0 6px;
  color: var(--teal-dark);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

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

h1 {
  margin-bottom: 0;
  font-size: clamp(2rem, 4vw, 4.4rem);
  line-height: 0.95;
  letter-spacing: 0;
}

.scoreboard {
  display: grid;
  grid-template-columns: repeat(3, minmax(92px, 1fr));
  gap: 8px;
  min-width: min(100%, 340px);
}

.scoreboard div {
  min-height: 76px;
  padding: 12px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 8px 24px rgba(23, 32, 28, 0.06);
}

.scoreboard span {
  display: block;
  font-size: 1.55rem;
  font-weight: 850;
}

.scoreboard label {
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 700;
}

.workspace {
  display: grid;
  grid-template-columns: minmax(260px, 330px) minmax(420px, 1fr) minmax(260px, 340px);
  gap: 16px;
  align-items: stretch;
}

.panel,
.stage {
  background: rgba(255, 255, 255, 0.82);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.controls,
.brief {
  padding: 14px;
}

.visual {
  overflow: hidden;
  aspect-ratio: 16 / 9;
  margin-bottom: 16px;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: var(--cream);
}

.visual img {
  width: 100%;
  height: 100%;
  display: block;
  object-fit: cover;
}

.control-group {
  display: grid;
  gap: 8px;
  margin-bottom: 16px;
}

.control-group label {
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 800;
}

select {
  width: 100%;
  min-height: 42px;
  padding: 0 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  color: var(--ink);
}

#modeSelect {
  display: none;
}

.segmented {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 6px;
}

.segment,
.primary,
.secondary,
.grade-grid button {
  min-height: 44px;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--ink);
  font-weight: 800;
}

.segment.active {
  border-color: var(--teal);
  background: var(--mint);
  color: var(--teal-dark);
}

.progress-block {
  display: grid;
  gap: 8px;
  margin: 18px 0;
}

.progress-meta {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  color: var(--muted);
  font-size: 0.8rem;
  font-weight: 800;
}

.progress-track {
  overflow: hidden;
  height: 10px;
  border-radius: 999px;
  background: #e8e1d3;
}

#progressFill {
  width: 0%;
  height: 100%;
  background: linear-gradient(90deg, var(--teal), var(--gold));
  transition: width 180ms ease;
}

.primary,
.secondary {
  width: 100%;
  margin-top: 8px;
}

.primary {
  border-color: var(--teal);
  background: var(--teal);
  color: #fff;
}

.secondary:hover,
.segment:hover,
.grade-grid button:hover {
  border-color: var(--teal);
}

.stage {
  display: grid;
  grid-template-rows: 1fr auto auto;
  min-height: 680px;
  padding: 18px;
}

.card-shell {
  min-height: 430px;
}

.flip-frame {
  perspective: 1400px;
}

.flashcard {
  position: relative;
  width: 100%;
  height: 100%;
  min-height: 430px;
  transform-style: preserve-3d;
  transition: transform 500ms ease-out, box-shadow 500ms ease-out;
  outline: none;
}

.flip-frame:hover .flashcard {
  transform: translateY(-2px);
  box-shadow: 0 18px 32px rgba(23, 32, 28, 0.14);
}

.flip-frame:focus-within .flashcard {
  border-radius: 8px;
  box-shadow: 0 0 0 3px rgba(15, 118, 110, 0.18), 0 18px 32px rgba(23, 32, 28, 0.14);
}

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

.flip-frame:hover .flashcard.flipped {
  transform: translateY(-2px) rotateY(180deg);
}

.card-face {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: clamp(20px, 4vw, 42px);
  backface-visibility: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
  background:
    radial-gradient(circle at 12% 12%, rgba(15, 118, 110, 0.12), transparent 28%),
    linear-gradient(135deg, #fffdf7 0%, #ffffff 56%, #ecf4f0 100%);
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.75);
}

.card-back {
  transform: rotateY(180deg);
  background:
    radial-gradient(circle at 85% 18%, rgba(189, 75, 56, 0.12), transparent 28%),
    linear-gradient(135deg, #ffffff 0%, #fbf4ec 54%, #eef6f4 100%);
}

.card-kicker {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  justify-content: space-between;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 850;
  text-transform: uppercase;
}

.card-kicker span {
  display: inline-flex;
  min-height: 28px;
  align-items: center;
  padding: 0 10px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.8);
}

.flashcard h2 {
  max-width: 920px;
  margin: 28px 0;
  font-size: clamp(2rem, 4.7vw, 4.8rem);
  line-height: 1.02;
  letter-spacing: 0;
}

.card-back h2 {
  font-size: clamp(1.7rem, 3.25vw, 3rem);
}

.flashcard h2.fit-dense {
  font-size: clamp(1.55rem, 2.8vw, 2.55rem);
  line-height: 1.08;
}

.flashcard h2.fit-tight {
  font-size: clamp(1.35rem, 2.35vw, 2.15rem);
  line-height: 1.12;
}

.flashcard p {
  max-width: 780px;
  margin-bottom: 0;
  color: var(--muted);
  font-size: clamp(1rem, 2vw, 1.26rem);
  line-height: 1.5;
}

.face-footer {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 18px;
}

.face-footer p {
  min-width: 0;
}

.face-flip {
  flex: 0 0 auto;
  min-height: 36px;
  padding: 0 12px;
  border: 0;
  border-radius: 999px;
  background: transparent;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 850;
  text-transform: uppercase;
}

.face-flip:hover,
.face-flip:focus-visible {
  color: var(--coral);
  background: rgba(189, 75, 56, 0.08);
  outline: none;
}

.actions {
  display: grid;
  grid-template-columns: 1fr 1.2fr 1fr;
  gap: 8px;
  margin: 14px 0 8px;
}

.actions .primary,
.actions .secondary {
  margin: 0;
}

.grade-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 8px;
}

.grade-grid button {
  display: grid;
  gap: 4px;
  min-height: 70px;
  padding: 10px;
  text-align: left;
}

.grade-grid button span {
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 650;
}

.brief {
  display: grid;
  gap: 18px;
  align-content: start;
}

.brief h2 {
  margin-bottom: 8px;
  font-size: 1.55rem;
  line-height: 1.12;
}

.brief p,
.brief li {
  color: var(--muted);
  line-height: 1.5;
}

.brief-list {
  padding-top: 14px;
  border-top: 1px solid var(--line);
}

.brief h3 {
  margin-bottom: 10px;
  font-size: 0.9rem;
  text-transform: uppercase;
}

.brief ul {
  margin: 0;
  padding-left: 18px;
}

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

@media (max-width: 1120px) {
  .workspace {
    grid-template-columns: 300px minmax(0, 1fr);
  }

  .brief {
    grid-column: 1 / -1;
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

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

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

  .scoreboard {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    min-width: 0;
  }

  .scoreboard div {
    min-height: 68px;
    padding: 10px;
  }

  .scoreboard span {
    font-size: 1.25rem;
  }

  .workspace,
  .brief {
    grid-template-columns: 1fr;
  }

  .stage {
    min-height: 610px;
    padding: 12px;
  }

  .card-shell,
  .flashcard {
    min-height: 390px;
  }

  .flashcard h2 {
    font-size: clamp(1.7rem, 9vw, 3.2rem);
  }

  .card-back h2,
  .flashcard h2.fit-dense,
  .flashcard h2.fit-tight {
    font-size: clamp(1.35rem, 6.8vw, 2.35rem);
  }

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

  .face-flip {
    align-self: flex-start;
  }

  .actions,
  .grade-grid {
    grid-template-columns: 1fr;
  }

  #modeSelect {
    display: block;
  }

  .segmented {
    display: none;
  }
}