:root {
  --bg: #0b0e14;
  --bg-elev: #11151c;
  --border: #1f2630;
  --border-strong: #2c3441;
  --text: #e6e8eb;
  --text-dim: #9aa3af;
  --text-faint: #6b7280;
  --accent: #60a5fa;
  --escape: #4b5563;
  --shadow: 0 1px 0 rgba(255, 255, 255, 0.04) inset, 0 8px 24px rgba(0, 0, 0, 0.35);
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family:
    -apple-system,
    BlinkMacSystemFont,
    "Pretendard",
    "Apple SD Gothic Neo",
    "Noto Sans KR",
    Segoe UI,
    Roboto,
    sans-serif;
  font-size: 15px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
  text-decoration: none;
}
a:hover {
  text-decoration: underline;
}

header {
  padding: 24px 32px 12px;
  border-bottom: 1px solid var(--border);
  background: var(--bg-elev);
}
header h1 {
  margin: 0 0 4px;
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -0.01em;
}
header h1 .badge {
  display: inline-block;
  margin-left: 8px;
  padding: 2px 8px;
  border-radius: 999px;
  background: var(--border);
  color: var(--text-dim);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.02em;
  vertical-align: 2px;
}
header .subtitle {
  margin: 0;
  color: var(--text-dim);
  font-size: 14px;
}
header .controls {
  margin-top: 12px;
  display: flex;
  gap: 8px;
  align-items: center;
}
header .controls button {
  padding: 6px 14px;
  border-radius: 6px;
  border: 1px solid var(--border-strong);
  background: var(--bg-elev);
  color: var(--text);
  font: inherit;
  cursor: pointer;
  transition: background 120ms;
}
header .controls button:hover {
  background: var(--border);
}
header .controls button:active {
  background: var(--border-strong);
}
header .controls .hint {
  margin-left: 8px;
  color: var(--text-faint);
  font-size: 12px;
}

/* Tabs */
.tabs {
  display: flex;
  gap: 4px;
  padding: 0 32px;
  border-bottom: 1px solid var(--border);
  background: var(--bg-elev);
}
.tab {
  padding: 10px 16px;
  border: 0;
  background: transparent;
  color: var(--text-dim);
  cursor: pointer;
  font: inherit;
  font-size: 14px;
  border-bottom: 2px solid transparent;
  margin-bottom: -1px;
  transition: color 120ms;
}
.tab:hover {
  color: var(--text);
}
.tab.active {
  color: var(--text);
  border-bottom-color: var(--accent);
}

main.grid {
  display: grid;
  grid-template-columns: minmax(0, 2fr) minmax(280px, 1fr);
  gap: 24px;
  padding: 20px 32px 32px;
  max-width: 1280px;
  margin: 0 auto;
}

.stage {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: 10px;
  box-shadow: var(--shadow);
  padding: 8px;
  position: relative;
}

.stage .controls {
  display: flex;
  gap: 8px;
  align-items: center;
  padding: 8px 8px 12px;
}
.stage .controls button {
  padding: 6px 14px;
  border-radius: 6px;
  border: 1px solid var(--border-strong);
  background: var(--bg-elev);
  color: var(--text);
  font: inherit;
  cursor: pointer;
  transition: background 120ms;
}
.stage .controls button:hover {
  background: var(--border);
}
.stage .controls .hint {
  margin-left: 4px;
  color: var(--text-faint);
  font-size: 12px;
}

/* Step view */
.step-stage {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: 10px;
  box-shadow: var(--shadow);
  padding: 16px;
}
.step-controls {
  display: flex;
  gap: 10px;
  align-items: center;
  flex-wrap: wrap;
  margin-bottom: 14px;
}
.step-controls button {
  padding: 7px 14px;
  border-radius: 6px;
  border: 1px solid var(--border-strong);
  background: var(--bg-elev);
  color: var(--text);
  font: inherit;
  cursor: pointer;
  transition: background 120ms;
}
.step-controls button:hover:not(:disabled) {
  background: var(--border);
}
.step-controls button:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}
.step-controls #step-next {
  border-color: var(--accent);
  color: var(--accent);
}
.step-controls #step-next:hover:not(:disabled) {
  background: rgba(96, 165, 250, 0.1);
}
.step-progress {
  color: var(--text-dim);
  font-size: 13px;
}
.step-progress strong {
  color: var(--text);
  font-weight: 700;
}
.step-stage-label {
  color: var(--text-faint);
  font-size: 12px;
  flex-basis: 100%;
}
.step-matrix-wrap {
  overflow-x: auto;
  margin: 0 -8px;
}
.step-matrix {
  width: 100%;
  border-collapse: collapse;
  font-size: 12px;
}
.step-matrix th {
  text-align: center;
  padding: 8px 4px;
  border-bottom: 1px solid var(--border-strong);
  color: var(--text-dim);
  font-weight: 600;
  font-size: 11px;
  position: sticky;
  top: 0;
  background: var(--bg-elev);
  white-space: nowrap;
  cursor: pointer;
  transition: color 120ms, background 120ms;
}
.step-matrix th.col-label {
  text-align: left;
  cursor: default;
  padding-left: 8px;
}
.step-matrix th:not(.col-label):hover,
.step-matrix th.active-step {
  color: var(--text);
  background: var(--border);
}
.step-matrix td {
  padding: 6px 4px;
  border-bottom: 1px solid var(--border);
  font-size: 11px;
  text-align: center;
  vertical-align: middle;
  white-space: nowrap;
}
.step-matrix td.label-cell {
  text-align: left;
  font-size: 12px;
  color: var(--text);
  padding-left: 8px;
  display: flex;
  align-items: center;
  gap: 8px;
  min-width: 180px;
}
.step-matrix td.label-cell svg {
  flex-shrink: 0;
}
.step-matrix tr:hover td {
  background: rgba(255, 255, 255, 0.02);
}

.cell-pending {
  color: var(--text-faint);
  font-weight: 400;
}
.cell-pass {
  color: var(--text-faint);
  background: rgba(255, 255, 255, 0.015);
}
.cell-caught {
  background: rgba(34, 197, 94, 0.18);
  color: #4ade80;
  font-weight: 700;
}
.cell-done {
  color: var(--text-faint);
  opacity: 0.3;
}
.cell-escaped {
  background: rgba(239, 68, 68, 0.18);
  color: #fca5a5;
  font-weight: 700;
}

svg.viz {
  display: block;
  width: 100%;
  height: auto;
  font-family: inherit;
}

/* Sieves */
.sieve-bar {
  fill: url(#mesh);
  stroke: var(--border-strong);
  stroke-width: 1.5;
}
.sieve-label-bg {
  fill: var(--bg-elev);
  stroke: var(--border-strong);
  stroke-width: 1;
}
.sieve-label-text {
  fill: var(--text);
  font-size: 13px;
  font-weight: 600;
  dominant-baseline: middle;
  pointer-events: none;
}
.sieve-label-tool {
  fill: var(--text-faint);
  font-size: 10px;
  dominant-baseline: middle;
  pointer-events: none;
}

/* Hover/active state on sieve */
.sieve {
  cursor: pointer;
}
.sieve:hover .sieve-bar,
.sieve.active .sieve-bar {
  stroke: var(--text);
  stroke-width: 2;
}
.sieve.flash .sieve-bar {
  animation: flash 600ms ease-out;
}
@keyframes flash {
  0% {
    stroke-width: 1.5;
    filter: brightness(1);
  }
  30% {
    stroke-width: 4;
    filter: brightness(1.6);
  }
  100% {
    stroke-width: 1.5;
    filter: brightness(1);
  }
}

/* Escape zone */
.escape-bar {
  fill: rgba(75, 85, 99, 0.15);
  stroke: var(--escape);
  stroke-width: 1.5;
  stroke-dasharray: 6 4;
}
.escape-label {
  fill: var(--text-dim);
  font-size: 12px;
  font-style: italic;
  dominant-baseline: middle;
  pointer-events: none;
}

/* Balls */
.ball {
  cursor: pointer;
}
.ball-shape {
  stroke: rgba(0, 0, 0, 0.4);
  stroke-width: 1;
  filter: drop-shadow(0 2px 3px rgba(0, 0, 0, 0.5));
}
.ball.checked .ball-shape {
  opacity: 0.55;
}
.ball.settled .ball-shape {
  filter: drop-shadow(0 2px 3px rgba(0, 0, 0, 0.7))
    drop-shadow(0 0 6px currentColor);
}
.ball-label {
  fill: var(--text);
  font-size: 9px;
  text-anchor: middle;
  dominant-baseline: middle;
  pointer-events: none;
  opacity: 0;
  transition: opacity 200ms 200ms;
}
.ball.settled .ball-label {
  opacity: 0.85;
}

/* Side panel */
.panel {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 18px 20px;
  box-shadow: var(--shadow);
  align-self: start;
  position: sticky;
  top: 16px;
  max-height: calc(100vh - 32px);
  overflow-y: auto;
}
.panel-tag {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.04em;
  margin-bottom: 8px;
  color: #000;
}
.panel h2 {
  margin: 0 0 4px;
  font-size: 17px;
  font-weight: 700;
}
.panel .panel-tool {
  color: var(--text-faint);
  font-size: 12px;
  margin: 0 0 14px;
}
.panel h3 {
  margin: 14px 0 6px;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-dim);
}
.panel ul {
  margin: 0;
  padding: 0;
  list-style: none;
}
.panel li {
  padding: 4px 0 4px 16px;
  position: relative;
  font-size: 13px;
  color: var(--text);
  line-height: 1.5;
}
.panel li::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 12px;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--text-faint);
}
.panel .panel-hint {
  margin-top: 16px;
  padding: 12px;
  border-radius: 6px;
  background: rgba(96, 165, 250, 0.08);
  border-left: 3px solid var(--accent);
  font-size: 13px;
  color: var(--text-dim);
}

footer {
  border-top: 1px solid var(--border);
  padding: 16px 32px;
  color: var(--text-faint);
  font-size: 13px;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

@media (max-width: 880px) {
  main.grid {
    grid-template-columns: 1fr;
  }
  .panel {
    position: static;
    max-height: none;
  }
  header,
  main.grid,
  footer {
    padding-left: 16px;
    padding-right: 16px;
  }
}