:root {
  color-scheme: light dark;
  --green: #0b6e4f;
  --bg: #f5f3ee;
  --ink: #1b1b1b;
  --muted: #6b6b6b;
  --card-bg: #ffffff;
  --card-back-bg: #14140f;
  --card-back-ink: #f2f0ea;
  --card-back-muted: #a6a49a;
  --border: #e5e2da;
  --border-dark: #34342a;
  --chip-bg: #2a2a22;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #101008;
    --ink: #f2f0ea;
    --muted: #a6a49a;
    --card-bg: #1c1c14;
    --border: #34342a;
  }
}

* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }

html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Helvetica Neue", Arial, sans-serif;
  overscroll-behavior-y: contain;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  background: var(--green);
  color: #fafaf7;
  padding: max(12px, env(safe-area-inset-top)) 16px 10px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}

.topbar h1 {
  margin: 0 0 10px;
  font-size: 1.1rem;
  font-weight: 700;
  text-align: center;
}

.filters {
  display: flex;
  gap: 6px;
  overflow-x: auto;
  padding-bottom: 2px;
  scrollbar-width: none;
  justify-content: center;
}
.filters::-webkit-scrollbar { display: none; }

.filter-chip {
  flex: 0 0 auto;
  border: 1px solid rgba(255,255,255,0.5);
  background: transparent;
  color: #fafaf7;
  border-radius: 999px;
  padding: 5px 12px;
  font-size: 0.8rem;
  white-space: nowrap;
}
.filter-chip.active {
  background: #fafaf7;
  color: var(--green);
  font-weight: 700;
  border-color: #fafaf7;
}

.stage {
  max-width: 520px;
  margin: 0 auto;
  padding: 14px 16px calc(20px + env(safe-area-inset-bottom));
  display: flex;
  flex-direction: column;
  min-height: calc(100vh - 76px);
}

.progress {
  text-align: center;
  color: var(--muted);
  font-size: 0.85rem;
  margin-bottom: 10px;
}

.card-wrap {
  position: relative;
  flex: 1;
  display: flex;
  perspective: 1400px;
  min-height: 380px;
}

.shuffle-btn {
  position: absolute;
  top: -6px;
  right: 0;
  z-index: 5;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  font-size: 1.05rem;
  color: var(--ink);
}
.shuffle-btn.active { background: var(--green); color: #fff; border-color: var(--green); }

.flashcard {
  flex: 1;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.5s cubic-bezier(.4,.2,.2,1);
  cursor: pointer;
}
.flashcard.flipped { transform: rotateY(180deg); }

.face {
  position: absolute;
  inset: 0;
  border-radius: 20px;
  backface-visibility: hidden;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.front {
  background: var(--card-bg);
  border: 1px solid var(--border);
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 24px;
  box-shadow: 0 4px 18px rgba(0,0,0,0.08);
}

.pos-chip {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--card-back-muted);
  background: var(--chip-bg);
  border-radius: 8px;
  padding: 4px 10px;
}

.front .pos-chip {
  color: var(--muted);
  background: var(--bg);
  margin-bottom: 18px;
}

.front-word {
  font-size: clamp(3rem, 13vw, 4.2rem);
  font-weight: 800;
  line-height: 1.15;
  word-break: break-word;
}

.tap-hint {
  margin-top: 22px;
  color: var(--muted);
  font-size: 0.85rem;
}

.back {
  background: var(--card-back-bg);
  color: var(--card-back-ink);
  transform: rotateY(180deg);
  padding: 20px;
  border: 1px solid var(--border-dark);
  box-shadow: 0 4px 18px rgba(0,0,0,0.3);
}

.word-chip {
  position: absolute;
  top: 16px;
  right: 16px;
  font-weight: 700;
  font-size: 0.95rem;
  text-transform: none;
  letter-spacing: 0;
  color: var(--card-back-ink);
}

.back-scroll {
  margin-top: 44px;
  overflow-y: auto;
  flex: 1;
  padding-right: 2px;
}

.back-scroll p { margin: 0 0 12px; line-height: 1.45; }

.definition { font-size: 1.575rem; font-weight: 600; }

.example-it { font-style: italic; color: #7fd8ae; }

.example-en { color: var(--card-back-muted); font-size: 0.92rem; }

.conj-block { margin-top: 6px; }
.conj-block.hidden { display: none; }

.conj-label {
  font-weight: 700;
  margin-bottom: 8px;
  font-size: 0.9rem;
}

.conj-table {
  border: 1px solid var(--border-dark);
  border-radius: 12px;
  overflow: hidden;
}

.conj-row {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  padding: 9px 14px;
  border-bottom: 1px solid var(--border-dark);
  font-size: 0.92rem;
}
.conj-row:last-child { border-bottom: none; }
.conj-row.highlight {
  background: rgba(11,110,79,0.35);
}
.conj-row.highlight .conj-it { font-weight: 700; color: #7fd8ae; }

.conj-it { color: var(--card-back-ink); }
.conj-en { color: var(--card-back-muted); text-align: right; }

.controls {
  display: flex;
  gap: 10px;
  margin-top: 16px;
}

.nav-btn {
  flex: 1;
  padding: 14px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--card-bg);
  color: var(--ink);
  font-size: 1rem;
  font-weight: 600;
}

.nav-btn.primary {
  background: var(--green);
  color: #fff;
  border-color: var(--green);
}

.nav-btn:active { opacity: 0.75; }