:root {
  --bg: #f4f5f7;
  --card-bg: #ffffff;
  --text: #1c1e21;
  --muted: #6b7280;
  --primary: #4f46e5;
  --primary-hover: #4338ca;
  --correct: #16a34a;
  --correct-bg: #dcfce7;
  --incorrect: #dc2626;
  --incorrect-bg: #fee2e2;
  --border: #e5e7eb;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  padding-bottom: env(safe-area-inset-bottom);
}

.app {
  max-width: 720px;
  margin: 0 auto;
  padding: 24px 16px 60px;
  padding-top: max(24px, env(safe-area-inset-top));
  padding-left: max(16px, env(safe-area-inset-left));
  padding-right: max(16px, env(safe-area-inset-right));
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
  gap: 12px;
}

.topbar h1 {
  font-size: 22px;
  margin: 0;
}

.sync-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin: -12px 0 20px;
  font-size: 12px;
  color: var(--muted);
}
.sync-bar .btn.link {
  padding: 2px 4px;
  font-size: 12px;
}

.topbar-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.status-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  font-weight: 600;
  padding: 6px 10px;
  border-radius: 20px;
  background: var(--card-bg);
  border: 1px solid var(--border);
  color: var(--muted);
  white-space: nowrap;
}
.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--muted);
  flex-shrink: 0;
}
.status-badge[data-state="online"] .status-dot { background: var(--correct); }
.status-badge[data-state="offline"] .status-dot { background: var(--muted); }
.status-badge[data-state="syncing"] .status-dot { background: var(--primary); animation: status-pulse 1s ease-in-out infinite; }
.status-badge[data-state="sync-failed"] .status-dot { background: var(--incorrect); }
.status-badge[data-state="online"] { color: var(--correct); }
.status-badge[data-state="sync-failed"] { color: var(--incorrect); }

@keyframes status-pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.35; }
}

.update-banner {
  display: none;
  align-items: center;
  justify-content: center;
  gap: 14px;
  flex-wrap: wrap;
  background: var(--primary);
  color: #fff;
  padding: 10px 16px;
  padding-top: max(10px, env(safe-area-inset-top));
  font-size: 14px;
  text-align: center;
}
.update-banner:not([hidden]) {
  display: flex;
}
.update-banner .btn.primary {
  background: #fff;
  color: var(--primary);
  padding: 6px 14px;
}
.update-banner .btn.primary:hover { background: #eceefc; }

.lang-btn {
  border: 1px solid var(--border);
  background: var(--card-bg);
  border-radius: 20px;
  padding: 8px 16px;
  font-weight: 600;
  cursor: pointer;
  font-size: 14px;
}
.lang-btn:hover { background: #f0f0f3; }

.card {
  background: var(--card-bg);
  border-radius: 14px;
  padding: 24px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
  margin-bottom: 16px;
}

.card.center { text-align: center; }

.hint { color: var(--muted); margin-top: -8px; }

.browse-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}
.browse-header h2 { margin: 0; }

.test-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin: 14px 0;
}

.test-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px 14px;
}

.test-row-title { font-weight: 600; }
.test-row-meta { color: var(--muted); font-size: 13px; margin-top: 2px; }
.test-row-status {
  display: inline-block;
  margin-top: 4px;
  font-size: 12px;
  font-weight: 600;
  color: var(--correct);
}

.test-row-actions {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}
.test-row-actions .btn { padding: 8px 14px; font-size: 14px; }

.resume-note {
  margin: -8px 0 12px;
  padding: 8px 12px;
  border-radius: 8px;
  background: #eceefc;
  color: var(--primary);
  font-size: 13px;
  font-weight: 600;
}
@media (prefers-color-scheme: dark) {
  .resume-note { background: #2a2c50; }
}

.dropzone {
  display: flex;
  align-items: center;
  justify-content: center;
  border: 2px dashed var(--border);
  border-radius: 12px;
  padding: 36px 16px;
  margin: 16px 0;
  cursor: pointer;
  color: var(--muted);
  text-align: center;
  transition: border-color .15s, background .15s;
}
.dropzone:hover, .dropzone.dragover {
  border-color: var(--primary);
  background: #f5f4ff;
}

.row {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 12px;
}
.row.center { justify-content: center; }

.btn {
  border: none;
  border-radius: 10px;
  padding: 12px 20px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
}
.btn.primary { background: var(--primary); color: #fff; }
.btn.primary:hover { background: var(--primary-hover); }
.btn.secondary { background: #eceefc; color: var(--primary); }
.btn.secondary:hover { background: #dfe1fb; }
.btn.link { background: none; color: var(--muted); padding: 12px 4px; text-decoration: underline; }

.error {
  color: var(--incorrect);
  font-weight: 600;
  min-height: 20px;
}

#formatExample {
  background: #f6f7f9;
  border-radius: 10px;
  padding: 16px;
  overflow-x: auto;
  font-size: 13px;
  line-height: 1.5;
}

.quiz-header {
  display: flex;
  justify-content: space-between;
  color: var(--muted);
  font-size: 14px;
  margin-bottom: 8px;
  font-weight: 600;
}

.question-image-wrap {
  display: none;
  flex-direction: column;
  align-items: center;
  margin: 4px 0 16px;
}
.question-image-wrap:not([hidden]) {
  display: flex;
}

.question-image {
  max-width: 100%;
  max-height: 320px;
  width: auto;
  height: auto;
  object-fit: contain;
  border-radius: 10px;
  border: 1px solid var(--border);
  cursor: zoom-in;
  background: #fff;
}

.image-error {
  color: var(--muted);
  font-style: italic;
  font-size: 14px;
  margin: 4px 0 0;
}

.image-modal {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.85);
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: 24px;
  cursor: zoom-out;
}
.image-modal.open { display: flex; }
.image-modal img {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
  border-radius: 6px;
}
.image-modal-close {
  position: absolute;
  top: 16px;
  right: 20px;
  background: none;
  border: none;
  color: #fff;
  font-size: 32px;
  line-height: 1;
  cursor: pointer;
}

.options {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin: 16px 0;
}

.option {
  border: 2px solid var(--border);
  border-radius: 10px;
  padding: 14px 16px;
  text-align: left;
  background: #fff;
  cursor: pointer;
  font-size: 15px;
  transition: border-color .15s, background .15s;
}

.option.has-image {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  text-align: center;
}

.option-image {
  max-width: 100%;
  max-height: 160px;
  width: auto;
  height: auto;
  object-fit: contain;
  border-radius: 8px;
}

.option-text:empty { display: none; }
.option:hover { border-color: var(--primary); }
.option.selected { border-color: var(--primary); background: #f5f4ff; }

.option.correct { border-color: var(--correct); background: var(--correct-bg); }
.option.incorrect { border-color: var(--incorrect); background: var(--incorrect-bg); }
.option[disabled] { cursor: default; }

.explanation {
  border-radius: 10px;
  padding: 16px;
  margin-top: 4px;
}
.explanation.correct { background: var(--correct-bg); }
.explanation.incorrect { background: var(--incorrect-bg); }

.explanation-title {
  font-weight: 700;
  margin-bottom: 6px;
}
.explanation.correct .explanation-title { color: var(--correct); }
.explanation.incorrect .explanation-title { color: var(--incorrect); }

.result-summary {
  font-size: 18px;
  color: var(--muted);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #16171b;
    --card-bg: #1f2125;
    --text: #eceef1;
    --muted: #9aa0a8;
    --border: #33363c;
    --correct-bg: #123a24;
    --incorrect-bg: #3a1414;
  }
  .btn.secondary { background: #2a2c50; }
  .btn.secondary:hover { background: #33356a; }
  .dropzone:hover, .dropzone.dragover { background: #24253a; }
  .option { background: #1f2125; }
  .option.selected { background: #24253a; }
  #formatExample { background: #26282d; color: #eceef1; }
  .question-image { background: #1f2125; }
}