:root{
  --bg: #0b1220;
  --card: rgba(255,255,255,0.06);
  --card2: rgba(255,255,255,0.10);
  --text: rgba(255,255,255,0.92);
  --muted: rgba(255,255,255,0.65);
  --border: rgba(255,255,255,0.12);

  --primary: #4f8cff;
  --good: #35d07f;
  --bad: #ff5b5b;
  --warn: #ffd24f;
}

*{
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Arial;
}

body{
  background: radial-gradient(1200px 600px at 30% 0%, rgba(79,140,255,0.25), transparent),
              radial-gradient(900px 500px at 100% 30%, rgba(53,208,127,0.20), transparent),
              var(--bg);
  color: var(--text);
  min-height: 100vh;
  padding: 18px;
}

.app{
  max-width: 950px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.topbar{
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
}

.title h1{
  font-size: 24px;
  letter-spacing: 0.2px;
}

.title p{
  color: var(--muted);
  margin-top: 6px;
  font-size: 14px;
}

.stats{
  display: flex;
  gap: 10px;
}

.stat{
  background: var(--card);
  border: 1px solid var(--border);
  padding: 10px 12px;
  border-radius: 16px;
  min-width: 120px;
}

.stat .label{
  display: block;
  font-size: 12px;
  color: var(--muted);
}

.stat .value{
  display: block;
  font-size: 18px;
  font-weight: 700;
  margin-top: 2px;
}

.card{
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 22px;
  padding: 16px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.35);
  backdrop-filter: blur(12px);
}

.card.small{
  padding: 14px;
}

.pillRow{
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 10px;
}

.pill{
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 7px 12px;
  border-radius: 999px;
  font-size: 13px;
  background: rgba(79,140,255,0.15);
  border: 1px solid rgba(79,140,255,0.25);
  color: rgba(255,255,255,0.92);
}

.pill.ghost{
  background: rgba(255,255,255,0.06);
  border: 1px solid var(--border);
  color: var(--muted);
}

h2{
  font-size: 18px;
  margin-bottom: 14px;
  line-height: 1.25;
}

.questionArea{
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 14px;
}

.option{
  width: 100%;
  text-align: left;
  background: var(--card2);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 12px 12px;
  border-radius: 16px;
  cursor: pointer;
  transition: transform 0.08s ease, border-color 0.15s ease;
  font-size: 15px;
}

.option:hover{
  transform: translateY(-1px);
  border-color: rgba(255,255,255,0.25);
}

.option.correct{
  border-color: rgba(53,208,127,0.8);
  background: rgba(53,208,127,0.18);
}

.option.wrong{
  border-color: rgba(255,91,91,0.85);
  background: rgba(255,91,91,0.16);
}

.writingBox{
  background: rgba(255,255,255,0.06);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 12px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

textarea{
  width: 100%;
  min-height: 90px;
  resize: vertical;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: rgba(0,0,0,0.25);
  color: var(--text);
  padding: 10px;
  font-size: 15px;
  outline: none;
}

.revealAnswer{
  background: rgba(255,210,79,0.14);
  border: 1px solid rgba(255,210,79,0.30);
  padding: 10px 12px;
  border-radius: 16px;
  color: rgba(255,255,255,0.95);
  display: none;
}

.revealAnswer.show{
  display: block;
}

.actions{
  display: flex;
  gap: 10px;
  justify-content: flex-end;
  flex-wrap: wrap;
}

.btn{
  border: 1px solid var(--border);
  background: rgba(255,255,255,0.06);
  color: var(--text);
  padding: 10px 14px;
  border-radius: 16px;
  cursor: pointer;
  font-weight: 650;
}

.btn:hover{
  border-color: rgba(255,255,255,0.25);
}

.btn.primary{
  background: rgba(79,140,255,0.22);
  border-color: rgba(79,140,255,0.35);
}

.btn.ghost{
  background: transparent;
}

.footerHint{
  margin-top: 8px;
  color: var(--muted);
  font-size: 13px;
}

/* Unit Bar */
.unitRow{
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.unitBtn{
  padding: 8px 12px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: rgba(255,255,255,0.05);
  color: var(--text);
  cursor: pointer;
  font-size: 13px;
  font-weight: 650;
}

.unitBtn:hover{
  border-color: rgba(255,255,255,0.25);
}

.unitBtn.active{
  background: rgba(79,140,255,0.22);
  border-color: rgba(79,140,255,0.35);
}

.unitHint{
  margin-top: 10px;
  font-size: 13px;
  color: var(--muted);
}

.settings h3{
  margin-bottom: 10px;
}

.grid2{
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-bottom: 12px;
}

.toggleRow{
  display: flex;
  gap: 10px;
  align-items: center;
  color: var(--muted);
  font-size: 14px;
  background: rgba(255,255,255,0.04);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 10px;
}

/* Small credits line */
.creditsLine{
  text-align: center;
  color: rgba(255,255,255,0.45);
  font-size: 12px;
  padding: 6px 0;
}

@media (max-width: 700px){
  .topbar{
    flex-direction: column;
  }

  .stats{
    width: 100%;
  }

  .stat{
    flex: 1;
  }

  .grid2{
    grid-template-columns: 1fr;
  }

  .actions{
    justify-content: stretch;
  }

  .btn{
    flex: 1;
  }
}