* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background:
    radial-gradient(1200px 500px at 20% -10%, #dbeafe 0%, rgba(219, 234, 254, 0) 60%),
    radial-gradient(900px 460px at 90% 0%, #e9d5ff 0%, rgba(233, 213, 255, 0) 55%),
    #f5f7ff;
  color: #0f172a;
}

.app {
  max-width: 860px;
  margin: 0 auto;
  min-height: 100vh;
  padding: 16px 12px 30px;
}

.header {
  background: rgba(255, 255, 255, 0.72);
  backdrop-filter: blur(8px);
  border: 1px solid rgba(148, 163, 184, 0.18);
  border-radius: 16px;
  padding: 14px 14px 12px;
  box-shadow: 0 10px 24px rgba(15, 23, 42, 0.06);
}

.header h1 {
  margin: 0;
  font-size: 1.28rem;
  letter-spacing: 0.2px;
}

.header p {
  margin: 6px 0 0;
  color: #475569;
  font-size: 0.88rem;
}

.tabs {
  margin-top: 14px;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

.tab {
  border: 1px solid #cbd5e1;
  background: rgba(255, 255, 255, 0.9);
  color: #0f172a;
  border-radius: 12px;
  padding: 9px 6px;
  font-weight: 600;
  transition: all 0.2s ease;
}

.tab.active {
  background: linear-gradient(135deg, #2563eb, #4f46e5);
  color: #fff;
  border-color: transparent;
  box-shadow: 0 8px 18px rgba(37, 99, 235, 0.32);
}

.panel {
  display: none;
  margin-top: 14px;
}

.panel.active {
  display: block;
}

.toolbar,
.privacy-hint {
  font-size: 0.8125rem;
  line-height: 1.45;
  color: var(--muted, #64748b);
  margin: 0 0 0.5rem;
  max-width: 52rem;
}

.practice-multi-confirm {
  margin-top: 0.75rem;
}

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

button {
  border: 0;
  border-radius: 10px;
  padding: 10px 12px;
  background: linear-gradient(135deg, #2563eb, #4f46e5);
  color: #fff;
  font-size: 0.9rem;
  font-weight: 600;
  box-shadow: 0 8px 18px rgba(37, 99, 235, 0.24);
  transition: transform 0.15s ease, box-shadow 0.2s ease;
}

button:active {
  transform: translateY(1px);
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.2);
}

button:disabled {
  opacity: 0.5;
  box-shadow: none;
}

button.danger {
  background: linear-gradient(135deg, #ef4444, #dc2626);
  box-shadow: 0 8px 18px rgba(220, 38, 38, 0.22);
}

.card {
  background: rgba(255, 255, 255, 0.92);
  border: 1px solid rgba(148, 163, 184, 0.2);
  border-radius: 16px;
  padding: 14px;
  box-shadow: 0 12px 28px rgba(15, 23, 42, 0.08);
}

#practiceStats {
  margin-bottom: 20px;
  color: #334155;
  font-weight: 500;
}

#practiceContainer {
  margin-bottom: 20px;
}

#practiceNextBtn {
  width: 100%;
}

.q-title {
  font-size: 1rem;
  line-height: 1.58;
  margin: 0 0 10px;
}

.q-meta {
  color: #475569;
  font-size: 0.85rem;
  margin-bottom: 8px;
}

.options {
  display: grid;
  gap: 9px;
}

.opt {
  border: 1px solid #cbd5e1;
  border-radius: 12px;
  padding: 10px;
  background: #fff;
  text-align: left;
  color: #0f172a;
  box-shadow: none;
  font-weight: 500;
}

.opt.selected {
  border-color: #2563eb;
  background: #eff6ff;
}

.opt.correct {
  border-color: #16a34a;
  background: #ecfdf5;
}

.opt.wrong {
  border-color: #dc2626;
  background: #fff5f5;
}

.result {
  margin-top: 8px;
  font-size: 0.92rem;
  color: #334155;
  white-space: pre-wrap;
}

.hint {
  color: #64748b;
  font-size: 0.85rem;
  margin: 0 0 8px;
}

textarea {
  width: 100%;
  border: 1px solid #cbd5e1;
  border-radius: 12px;
  padding: 10px;
  font-size: 0.9rem;
  background: rgba(255, 255, 255, 0.95);
}

input[type="text"],
input[type="password"] {
  width: 100%;
  border: 1px solid #cbd5e1;
  border-radius: 12px;
  padding: 10px;
  font-size: 0.9rem;
  background: rgba(255, 255, 255, 0.95);
  margin-bottom: 8px;
}

.list {
  display: grid;
  gap: 10px;
}

.chip {
  display: inline-block;
  background: #e0e7ff;
  color: #3730a3;
  padding: 3px 9px;
  border-radius: 999px;
  font-size: 0.78rem;
  font-weight: 600;
}

.bottom-submit-wrap {
  position: fixed;
  left: 12px;
  right: 12px;
  bottom: 20px;
  z-index: 30;
}

.bottom-submit-wrap button {
  width: 100%;
  padding: 12px;
  font-size: 1rem;
  border-radius: 14px;
}

#panelTest {
  padding-bottom: 90px;
}

#panelTest h3 {
  margin: 16px 2px 10px;
  font-size: 0.98rem;
  color: #1e293b;
  letter-spacing: 0.2px;
}

@media (min-width: 900px) {
  .app {
    padding-top: 22px;
  }
  .tabs {
    max-width: 620px;
  }
}