:root {
  --blue: #2563eb;
  --blue-soft: #eff4ff;
  --ink: #0f172a;
  --muted: #64748b;
  --line: #e5e7eb;
  --paper: #ffffff;
  --page: #f8fafc;
  --success: #16a34a;
  --success-bg: #ecfdf3;
  --warning: #d97706;
  --warning-bg: #fff7ed;
  --danger: #dc2626;
  --danger-bg: #fef2f2;
  --star: #f59e0b;

  --font: "DM Sans", sans-serif;
  --radius: 12px;
  --radius-sm: 10px;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.04);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font-family: var(--font);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; }

button {
  font-family: inherit;
  cursor: pointer;
}

/* ---------- Topbar ---------- */

.topbar {
  background: var(--paper);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 20;
}

.topbar-inner {
  max-width: 980px;
  margin: 0 auto;
  padding: 14px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
  color: var(--blue);
}

.brand-mark {
  display: flex;
  color: var(--blue);
  line-height: 0;
}

.brand-word {
  font-weight: 700;
  font-size: 1.2rem;
  letter-spacing: -0.02em;
}

.topbar-nav {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  border: none;
  background: transparent;
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 500;
  padding: 8px 12px;
  border-radius: 8px;
  transition: color 0.15s ease, background 0.15s ease;
}

.nav-link:hover:not(:disabled) {
  color: var(--blue);
  background: var(--blue-soft);
}

.nav-link:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

/* ---------- Layout shells ---------- */

.screen {
  max-width: 980px;
  margin: 0 auto;
  padding: 36px 24px 80px;
}

.footer {
  text-align: center;
  padding: 20px 24px 48px;
  color: var(--muted);
  font-size: 0.82rem;
}

.back-link {
  background: none;
  border: none;
  color: var(--blue);
  font-size: 0.9rem;
  font-weight: 600;
  padding: 0;
  margin-bottom: 24px;
}

/* ---------- Screen 1: Search ---------- */

.search-wrap {
  max-width: 640px;
  margin: 40px auto 0;
  text-align: center;
}

.search-title {
  font-size: clamp(1.65rem, 3.4vw, 2.25rem);
  font-weight: 700;
  line-height: 1.2;
  margin: 0 0 14px;
  letter-spacing: -0.025em;
}

.search-sub {
  color: var(--muted);
  font-size: 1rem;
  margin: 0 0 32px;
}

.search-form {
  display: flex;
  gap: 8px;
  border: 1.5px solid var(--line);
  border-radius: var(--radius);
  padding: 6px;
  background: var(--paper);
  box-shadow: var(--shadow-sm);
}

.search-input {
  flex: 1;
  border: none;
  outline: none;
  font-family: inherit;
  font-size: 1rem;
  padding: 12px 14px;
  background: transparent;
  color: var(--ink);
}

.search-submit {
  background: var(--blue);
  color: white;
  border: none;
  border-radius: 8px;
  padding: 12px 24px;
  font-weight: 600;
  font-size: 0.95rem;
  transition: filter 0.15s ease;
}

.search-submit:hover { filter: brightness(1.05); }
.search-submit:disabled { opacity: 0.65; cursor: wait; }

.chip-row {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px;
  margin-top: 22px;
}

.chip {
  border: 1px solid var(--line);
  background: var(--paper);
  color: var(--ink);
  padding: 7px 14px;
  font-size: 0.85rem;
  border-radius: 999px;
  transition: border-color 0.15s ease, color 0.15s ease;
}

.chip:hover {
  border-color: var(--blue);
  color: var(--blue);
}

.search-note {
  margin-top: 28px;
  font-size: 0.8rem;
  color: var(--muted);
}

/* ---------- Screen 2: Product summary ---------- */

.product-summary {
  display: grid;
  grid-template-columns: 88px 1fr auto;
  gap: 20px 24px;
  align-items: center;
  margin-bottom: 40px;
}

.product-thumb {
  width: 88px;
  height: 88px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--line);
  background:
    linear-gradient(145deg, #f1f5f9 0%, #e2e8f0 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  flex-shrink: 0;
}

.product-thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.product-thumb-initials {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--muted);
  letter-spacing: -0.02em;
}

.product-info { min-width: 0; }

.results-product {
  font-size: clamp(1.35rem, 2.6vw, 1.75rem);
  font-weight: 700;
  margin: 0 0 8px;
  letter-spacing: -0.025em;
  line-height: 1.25;
}

.confidence-line {
  display: flex;
  align-items: center;
  gap: 6px;
  margin: 0;
  color: var(--muted);
  font-size: 0.92rem;
}

.confidence-check {
  display: inline-flex;
  color: var(--blue);
  flex-shrink: 0;
}

.trust-score-block {
  display: flex;
  align-items: center;
  gap: 14px;
}

.donut-wrap {
  position: relative;
  width: 108px;
  height: 108px;
  flex-shrink: 0;
}

.donut {
  display: block;
  width: 108px;
  height: 108px;
}

.donut-track {
  fill: none;
  stroke: #eef2f7;
  stroke-width: 10;
}

.donut-progress {
  fill: none;
  stroke-width: 10;
  stroke-linecap: round;
  stroke-dasharray: 314.16;
  stroke-dashoffset: 314.16;
  transition: stroke-dashoffset 0.6s ease, stroke 0.3s ease;
}

.donut-center {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
  line-height: 1;
}

.donut-score {
  font-size: 1.45rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--ink);
}

.donut-denom {
  font-size: 0.72rem;
  font-weight: 500;
  color: var(--muted);
  margin-left: 1px;
  align-self: center;
  padding-top: 0.35em;
}

.trust-label {
  margin: 0;
  font-size: 1.05rem;
  font-weight: 700;
  white-space: nowrap;
}

.trust-label.low { color: var(--danger); }
.trust-label.medium { color: var(--warning); }
.trust-label.high { color: var(--success); }

/* ---------- Section headings ---------- */

.section-heading {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 1.05rem;
  font-weight: 700;
  margin: 0 0 14px;
  letter-spacing: -0.01em;
}

.info-tip {
  color: var(--muted);
  font-size: 0.85rem;
  font-weight: 500;
  cursor: help;
}

/* ---------- AI review summary ---------- */

.summary-section { margin-bottom: 36px; }

.summary-section[hidden] { display: none; }

.summary-body {
  border: 1px solid var(--line);
  background: var(--paper);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  padding: 18px 20px;
  display: grid;
  gap: 18px;
}

.summary-block + .summary-block {
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.summary-block-title {
  margin: 0 0 8px;
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--muted);
}

.summary-block-text {
  margin: 0;
  font-size: 0.95rem;
  line-height: 1.55;
}

.summary-block-list {
  margin: 0;
  padding-left: 1.2rem;
  font-size: 0.95rem;
  line-height: 1.55;
}

.summary-block-list li + li {
  margin-top: 8px;
}

.summary-body p {
  margin: 0 0 12px;
  font-size: 0.95rem;
}

.summary-body p:last-child { margin-bottom: 0; }

.summary-note {
  margin: 10px 2px 0;
  color: var(--muted);
  font-size: 0.8rem;
}

/* ---------- Sources ---------- */

.sources-section { margin-bottom: 36px; }

.source-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
}

.source-card {
  border: 1px solid var(--line);
  background: var(--paper);
  border-radius: var(--radius);
  padding: 18px 14px 16px;
  text-align: center;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  min-height: 128px;
}

.source-logo {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.source-logo img,
.source-logo svg {
  width: 40px;
  height: 40px;
  display: block;
  border-radius: 8px;
}

.source-count {
  margin: 0;
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--ink);
}

.source-rating {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  margin-top: auto;
  min-height: 22px;
}

.source-rating-value {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--ink);
}

.source-stars {
  display: inline-flex;
  gap: 1px;
  color: var(--star);
  font-size: 0.72rem;
  letter-spacing: -0.5px;
}

.source-rating-empty {
  color: var(--muted);
  font-size: 0.95rem;
}

/* ---------- Signals (each flag is its own card) ---------- */

.signals-section {
  margin-bottom: 40px;
  background: transparent;
  border: none;
  box-shadow: none;
  padding: 0;
}

.signal-stack {
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin: 0;
  padding: 0;
  background: transparent;
  border: none;
}

.signal-card {
  display: flex;
  align-items: center;
  gap: 14px;
  width: 100%;
  margin: 0;
  padding: 16px 18px;
  text-align: left;
  font: inherit;
  color: inherit;
  border: 1px solid transparent;
  border-radius: 14px;
  box-shadow: none;
  appearance: none;
  -webkit-appearance: none;
  background: #f8fafc;
  border-color: #e2e8f0;
}

/* Distinct pastel per signal type (so cards never all look the same) */
.signal-card.type-burst_detection {
  background: #fff7ed;
  border-color: #fdba74;
}
.signal-card.type-duplicate_text,
.signal-card.type-duplicate_text_skipped {
  background: #fef2f2;
  border-color: #fca5a5;
}
.signal-card.type-thin_reviewer_history,
.signal-card.type-thin_reviewer_history_skipped {
  background: #eff6ff;
  border-color: #93c5fd;
}
.signal-card.type-rating_pile {
  background: #f0fdfa;
  border-color: #5eead4;
}
.signal-card.type-thin_text {
  background: #f8fafc;
  border-color: #cbd5e1;
}
.signal-card.type-youtube_activity {
  background: #fff1f2;
  border-color: #fda4af;
}
.signal-card.type-repeat_reviewer {
  background: #ecfdf5;
  border-color: #6ee7b7;
}
.signal-card.type-clean {
  background: #ecfdf3;
  border-color: #86efac;
}

/* Severity still drives a stronger tint when flagged */
.signal-card.severity-warning.type-burst_detection,
.signal-card.severity-danger.type-burst_detection {
  background: #ffedd5;
  border-color: #fb923c;
}
.signal-card.severity-warning.type-duplicate_text,
.signal-card.severity-danger.type-duplicate_text {
  background: #fee2e2;
  border-color: #f87171;
}
.signal-card.severity-warning.type-thin_reviewer_history,
.signal-card.severity-danger.type-thin_reviewer_history,
.signal-card.severity-warning.type-thin_reviewer_history_skipped {
  background: #dbeafe;
  border-color: #60a5fa;
}
.signal-card.severity-warning.type-rating_pile,
.signal-card.severity-danger.type-rating_pile {
  background: #ccfbf1;
  border-color: #2dd4bf;
}
.signal-card.severity-warning.type-thin_text,
.signal-card.severity-danger.type-thin_text {
  background: #e2e8f0;
  border-color: #94a3b8;
}
.signal-card.severity-warning.type-youtube_activity,
.signal-card.severity-danger.type-youtube_activity {
  background: #ffe4e6;
  border-color: #fb7185;
}
.signal-card.severity-warning.type-repeat_reviewer,
.signal-card.severity-danger.type-repeat_reviewer {
  background: #d1fae5;
  border-color: #34d399;
}

.signal-card.clickable {
  cursor: pointer;
  transition: filter 0.15s ease, box-shadow 0.15s ease;
}

.signal-card.clickable:hover {
  filter: brightness(0.985);
  box-shadow: var(--shadow-sm);
}

.signal-card.clickable:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 2px;
}

.signal-icon {
  width: 30px;
  height: 30px;
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  font-size: 0.9rem;
  font-weight: 700;
  color: #fff;
}

.signal-icon.warning { background: #d97706; }
.signal-icon.danger  { background: #dc2626; }
.signal-icon.success { background: #16a34a; }

.signal-body {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.signal-title {
  display: block;
  font-weight: 700;
  font-size: 0.98rem;
  color: var(--ink);
  letter-spacing: -0.01em;
  line-height: 1.3;
}

.signal-desc {
  display: block;
  font-size: 0.9rem;
  color: var(--muted);
  line-height: 1.4;
  font-weight: 400;
}

.signal-meta {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
  margin-left: 8px;
}

.signal-severity-label {
  font-size: 0.92rem;
  font-weight: 700;
}

.signal-severity-label.warning { color: #d97706; }
.signal-severity-label.danger  { color: #dc2626; }
.signal-severity-label.success { color: #16a34a; }

.signal-chevron {
  color: var(--muted);
  font-size: 1.25rem;
  line-height: 1;
}

/* ---------- Screen 3: Signal detail ---------- */

.detail-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 10px;
}

.detail-severity-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  display: inline-block;
}

.detail-title {
  font-size: 1.45rem;
  font-weight: 700;
  margin: 0;
  letter-spacing: -0.02em;
  text-transform: capitalize;
}

.detail-description {
  color: var(--muted);
  font-size: 0.95rem;
  max-width: 640px;
  margin: 0 0 28px;
}

.detail-evidence { display: flex; flex-direction: column; gap: 20px; }

.evidence-block {
  border: 1px solid var(--line);
  background: var(--paper);
  border-radius: var(--radius);
  padding: 20px;
}

.evidence-block h3 {
  font-size: 0.95rem;
  margin: 0 0 14px;
}

.burst-chart {
  display: flex;
  align-items: flex-end;
  gap: 3px;
  height: 120px;
  border-bottom: 1px solid var(--line);
  padding-bottom: 4px;
}

.burst-bar {
  flex: 1;
  background: var(--blue);
  min-width: 2px;
  border-radius: 2px 2px 0 0;
}

.dup-pair {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px;
  margin-bottom: 10px;
  font-size: 0.85rem;
}

.dup-pair:last-child { margin-bottom: 0; }

.dup-pair-sim {
  font-size: 0.76rem;
  font-weight: 600;
  color: var(--danger);
  margin: 0 0 8px;
}

.dup-pair-text {
  font-size: 0.82rem;
  color: #334155;
  background: var(--page);
  border-radius: 6px;
  padding: 8px 10px;
  margin: 0 0 6px;
  white-space: pre-wrap;
}

.dup-pair-meta {
  font-size: 0.72rem;
  color: var(--muted);
  margin: 0;
}

.empty-evidence {
  color: var(--muted);
  font-size: 0.88rem;
}

.evidence-json {
  margin: 0;
  padding: 12px 14px;
  overflow: auto;
  font-size: 0.8rem;
  line-height: 1.45;
  background: var(--page);
  border-radius: 8px;
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
}

/* ---------- Responsive ---------- */

@media (max-width: 820px) {
  .source-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 680px) {
  .topbar-inner { padding: 12px 16px; }
  .topbar-nav .nav-link span,
  .nav-link { font-size: 0.82rem; padding: 8px; }

  .product-summary {
    grid-template-columns: 72px 1fr;
  }

  .product-thumb { width: 72px; height: 72px; }

  .trust-score-block {
    grid-column: 1 / -1;
    justify-content: flex-start;
    padding-top: 4px;
  }

  .screen { padding: 28px 16px 64px; }
}

@media (max-width: 520px) {
  .source-grid { grid-template-columns: 1fr 1fr; }
  .signal-card { align-items: flex-start; }
  .nav-link { gap: 4px; }
}

/* ---------- Utility ---------- */

[hidden] { display: none !important; }