.kd-root {
  --kd-bg: #f7f8fb;
  --kd-card: #ffffff;
  --kd-text: #1f2937;
  --kd-muted: #667085;
  --kd-border: #e5e7eb;
  --kd-accent: #2563eb;
  --kd-accent-dark: #1d4ed8;
  --kd-danger: #dc2626;
  --kd-success: #15803d;
  --kd-warning: #b45309;
  color: var(--kd-text);
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.kd-root *, .kd-root *::before, .kd-root *::after {
  box-sizing: border-box;
}

.kd-app, .kd-subject-menu {
  max-width: 960px;
  margin: 0 auto;
}

.kd-header {
  padding: 24px 20px;
  margin: 0 0 16px;
  border: 1px solid var(--kd-border);
  border-radius: 18px;
  background: linear-gradient(180deg, #ffffff, #f9fafb);
}

.kd-eyebrow {
  margin: 0 0 6px;
  color: var(--kd-accent);
  font-weight: 700;
  font-size: 0.9rem;
  letter-spacing: 0.04em;
}

.kd-header h1, .kd-subject-menu h2 {
  margin: 0 0 8px;
  line-height: 1.35;
  font-size: clamp(1.5rem, 3vw, 2.2rem);
}

.kd-lead, .kd-note {
  color: var(--kd-muted);
  line-height: 1.8;
}

.kd-box, .kd-card, .kd-weak-row, .kd-toolbar, .kd-stats, .kd-summary-cards > div {
  background: var(--kd-card);
  border: 1px solid var(--kd-border);
  border-radius: 16px;
  box-shadow: 0 8px 20px rgba(15, 23, 42, 0.04);
}

.kd-box {
  padding: 20px;
  margin: 16px 0;
}

.kd-error {
  border-color: #fecaca;
  background: #fff7f7;
}

.kd-toolbar {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  align-items: end;
  padding: 14px;
  margin: 12px 0;
}

.kd-toolbar label {
  display: grid;
  gap: 6px;
  color: var(--kd-muted);
  font-size: 0.9rem;
  min-width: 150px;
}

.kd-toolbar select, .kd-toolbar input[type="text"] {
  min-height: 42px;
  border: 1px solid var(--kd-border);
  border-radius: 10px;
  padding: 8px 10px;
  color: var(--kd-text);
  background: #fff;
}

.kd-check {
  display: flex !important;
  grid-template-columns: auto 1fr;
  align-items: center;
  min-height: 42px;
}

.kd-stats {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  padding: 12px;
  margin: 12px 0;
}

.kd-stats span {
  display: inline-flex;
  gap: 4px;
  align-items: center;
  padding: 6px 10px;
  border-radius: 999px;
  background: var(--kd-bg);
  color: var(--kd-muted);
  font-size: 0.92rem;
}

.kd-stats strong {
  color: var(--kd-text);
}

.kd-card {
  padding: 20px;
  margin: 16px 0;
}

.kd-card-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0 0 12px;
}

.kd-card-meta span,
.kd-card-meta a.kd-source-link {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  padding: 4px 8px;
  border-radius: 999px;
  background: #eef2ff;
  color: #3730a3 !important;
  font-size: 0.82rem;
  font-weight: 700;
  text-decoration: none !important;
}

.kd-card-meta a.kd-source-link:hover,
.kd-card-meta a.kd-source-link:focus {
  background: #dbeafe;
  color: #1d4ed8 !important;
}

.kd-card h2 {
  margin: 0 0 12px;
  font-size: 1.25rem;
}

.kd-choice {
  padding: 18px;
  margin: 0 0 16px;
  border-radius: 14px;
  background: #f9fafb;
  border: 1px solid var(--kd-border);
  line-height: 1.9;
  font-size: 1.05rem;
  font-weight: 650;
}

.kd-answer-buttons, .kd-card-actions, .kd-cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
}

.kd-btn,
.kd-btn-ghost,
.kd-btn-danger,
.kd-btn-accent {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  appearance: none;
  border: 1px solid var(--kd-accent);
  border-radius: 999px;
  background: #fff;
  color: var(--kd-accent) !important;
  padding: 10px 16px;
  min-height: 44px;
  line-height: 1.2;
  font-weight: 700;
  text-decoration: none !important;
  cursor: pointer;
  transition: transform 0.12s ease, background-color 0.12s ease, border-color 0.12s ease, box-shadow 0.12s ease;
}

.kd-btn:hover, .kd-btn:focus,
.kd-btn-ghost:hover, .kd-btn-ghost:focus,
.kd-btn-danger:hover, .kd-btn-danger:focus,
.kd-btn-accent:hover, .kd-btn-accent:focus {
  background: #eff6ff;
  border-color: var(--kd-accent-dark);
  color: var(--kd-accent-dark) !important;
  transform: translateY(-1px);
}

.kd-btn:active,
.kd-btn-ghost:active,
.kd-btn-danger:active,
.kd-btn-accent:active {
  background: #dbeafe;
  border-color: var(--kd-accent-dark);
  color: var(--kd-accent-dark) !important;
  box-shadow: inset 0 0 0 1px rgba(29, 78, 216, 0.08);
}

.kd-btn:focus-visible,
.kd-btn-ghost:focus-visible,
.kd-btn-danger:focus-visible,
.kd-btn-accent:focus-visible,
.kd-toolbar select:focus-visible,
.kd-toolbar input[type="text"]:focus-visible,
.kd-source-link:focus-visible,
.kd-card-title:focus-visible {
  outline: 3px solid rgba(37, 99, 235, 0.35);
  outline-offset: 3px;
}

.kd-card-title:focus {
  outline-offset: 4px;
}

.kd-feedback {
  margin: 16px 0;
}

.kd-feedback-head {
  display: grid;
  gap: 4px;
  padding: 12px 14px;
  border-radius: 14px;
  margin: 0 0 12px;
}

.kd-feedback-head span {
  color: var(--kd-muted);
  font-size: 0.92rem;
}

.kd-feedback-head.is-correct {
  background: #ecfdf3;
  border: 1px solid #bbf7d0;
  color: var(--kd-success);
}

.kd-feedback-head.is-wrong {
  background: #fef2f2;
  border: 1px solid #fecaca;
  color: var(--kd-danger);
}

.kd-feedback-head.is-unknown {
  background: #fffbeb;
  border: 1px solid #fde68a;
  color: var(--kd-warning);
}

.kd-explain {
  display: grid;
  grid-template-columns: 88px 1fr;
  gap: 8px 12px;
  margin: 0 0 12px;
  line-height: 1.8;
}

.kd-explain dt {
  color: var(--kd-muted);
  font-weight: 700;
}

.kd-explain dd {
  margin: 0;
}

.kd-explain-small {
  grid-template-columns: 70px 1fr;
  font-size: 0.95rem;
}

.kd-card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 12px 0;
}

.kd-tag {
  display: inline-flex;
  padding: 4px 8px;
  border-radius: 999px;
  background: #f3f4f6;
  color: #374151;
  font-size: 0.82rem;
  font-weight: 700;
}

.kd-result-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.kd-result-box h2, .kd-recommend h2 {
  margin-top: 0;
}

.kd-result-grid h3, .kd-result-grid h2 {
  margin: 0 0 8px;
}

.kd-result-grid ol, .kd-rank-list {
  margin: 0;
  padding-left: 1.25em;
}

.kd-rank-list li {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  padding: 8px 0;
  border-bottom: 1px dashed var(--kd-border);
}

.kd-summary-cards {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 10px;
  margin: 12px 0;
}

.kd-summary-cards > div {
  padding: 14px;
  display: grid;
  gap: 4px;
}

.kd-summary-cards strong {
  font-size: 1.8rem;
}

.kd-summary-cards span {
  color: var(--kd-muted);
  font-weight: 700;
}

.kd-weak-row {
  padding: 16px;
  margin: 12px 0;
}

.kd-weak-row.is-resolved {
  opacity: 0.65;
}

.kd-row-footer {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: space-between;
  align-items: center;
  color: var(--kd-muted);
  font-size: 0.92rem;
}

.kd-toast {
  position: fixed;
  left: 50%;
  bottom: 24px;
  transform: translateX(-50%) translateY(20px);
  z-index: 99999;
  padding: 10px 14px;
  max-width: min(92vw, 420px);
  border-radius: 999px;
  background: #111827;
  color: #fff;
  text-align: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease, transform 0.2s ease;
}

.kd-toast.is-show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

.kd-subject-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.kd-subject-card {
  display: grid;
  gap: 8px;
  padding: 16px;
  border: 1px solid var(--kd-border);
  border-radius: 16px;
  background: #fff;
  color: var(--kd-text) !important;
  text-decoration: none !important;
  box-shadow: 0 8px 20px rgba(15, 23, 42, 0.04);
}

.kd-subject-card:hover, .kd-subject-card:focus {
  border-color: var(--kd-accent);
}

.kd-subject-card strong {
  font-size: 1.02rem;
}

.kd-subject-card span {
  color: var(--kd-muted);
  line-height: 1.65;
  font-size: 0.9rem;
}

.kd-subject-card--all {
  background: #eff6ff;
}

@media (max-width: 720px) {
  .kd-header, .kd-card, .kd-box, .kd-weak-row {
    border-radius: 14px;
    padding: 16px;
  }

  .kd-toolbar {
    display: grid;
  }

  .kd-toolbar label {
    min-width: 0;
  }

  .kd-result-grid, .kd-summary-cards, .kd-subject-grid {
    grid-template-columns: 1fr;
  }

  .kd-explain, .kd-explain-small {
    grid-template-columns: 1fr;
  }

  .kd-answer-buttons .kd-btn, .kd-card-actions .kd-btn, .kd-cta-row .kd-btn {
    width: 100%;
    justify-content: center;
    text-align: center;
  }
}

@media (prefers-reduced-motion: reduce) {
  .kd-btn,
  .kd-btn-ghost,
  .kd-btn-danger,
  .kd-btn-accent,
  .kd-toast {
    transition: none;
  }

  .kd-btn:hover,
  .kd-btn:focus,
  .kd-btn-ghost:hover,
  .kd-btn-ghost:focus,
  .kd-btn-danger:hover,
  .kd-btn-danger:focus,
  .kd-btn-accent:hover,
  .kd-btn-accent:focus {
    transform: none;
  }
}