.step-viewer {
  background: var(--surface);
  border: 2px solid var(--border);
  box-shadow: 4px 4px 0 var(--surface-alt);
  padding: 20px;
  margin-bottom: 20px;
}

.step-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: 16px;
}

.step-counter {
  font-family: "Press Start 2P", "Courier New", monospace;
  font-size: 0.6rem;
  color: var(--text-dim);
}

.step-title {
  font-family: "Press Start 2P", "Courier New", monospace;
  font-size: 0.9rem;
  color: var(--accent);
}

.step-visual {
  min-height: 220px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--surface-alt);
  border: 2px dashed var(--border);
  padding: 20px;
  margin-bottom: 16px;
}

.step-scene {
  display: none;
  width: 100%;
}

.step-scene.active {
  display: flex;
  align-items: center;
  justify-content: center;
}

.step-caption {
  color: var(--text-dim);
  margin: 0 0 16px;
}

.step-nav {
  display: flex;
  gap: 8px;
}

.step-btn {
  font-family: "Press Start 2P", "Courier New", monospace;
  background: var(--surface-alt);
  color: var(--text-dim);
  border: 2px solid var(--border);
  padding: 10px 16px;
  font-size: 0.65rem;
  cursor: pointer;
  box-shadow: 3px 3px 0 var(--bg);
}

.step-btn:hover:not(:disabled) {
  color: var(--text);
  border-color: var(--accent);
}

.step-btn:disabled {
  opacity: 0.35;
  cursor: default;
}

/* ===== Pixelated hand grid, sitting in a wider "camera frame" of noise ===== */

.pixel-grid {
  position: relative;
  display: grid;
  gap: 2px;
  width: 100%;
  max-width: 340px;
  overflow: hidden;
}

.hand-grid {
  grid-template-columns: repeat(14, 1fr);
}

.px {
  aspect-ratio: 1;
}

/* ===== Detection scan + result ===== */

.pixel-grid.scanning {
  position: relative;
}

.scan-line {
  position: absolute;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--accent);
  box-shadow: 0 0 10px 2px var(--accent);
  animation: scan 2.5s linear infinite;
}

@keyframes scan {
  0% { top: 0%; }
  50% { top: 96%; }
  100% { top: 0%; }
}

.detection-box {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.detection-frame {
  position: absolute;
  border: 2px solid #6fdc8c;
  box-shadow: 0 0 14px 1px rgba(111, 220, 140, 0.6);
  pointer-events: none;
}

.detection-label {
  font-family: "Press Start 2P", "Courier New", monospace;
  font-size: 0.6rem;
  color: #6fdc8c;
  border: 2px solid #6fdc8c;
  padding: 6px 10px;
}

/* ===== Training step ===== */

.training-scene {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  width: 100%;
}

.training-examples {
  display: flex;
  gap: 10px;
}

.example-card {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 2px solid var(--border);
  box-shadow: 3px 3px 0 var(--bg);
}

.example-check {
  color: #14301f;
  font-weight: bold;
  font-size: 1.1rem;
  opacity: 0;
  animation: check-in 3s ease-in-out infinite;
}

.training-examples .example-card:nth-child(1) .example-check { animation-delay: 0s; }
.training-examples .example-card:nth-child(2) .example-check { animation-delay: 0.25s; }
.training-examples .example-card:nth-child(3) .example-check { animation-delay: 0.5s; }
.training-examples .example-card:nth-child(4) .example-check { animation-delay: 0.75s; }
.training-examples .example-card:nth-child(5) .example-check { animation-delay: 1s; }

@keyframes check-in {
  0%, 8% { opacity: 0; transform: scale(0.5); }
  18%, 70% { opacity: 1; transform: scale(1); }
  85%, 100% { opacity: 0; transform: scale(0.5); }
}

.training-bar-track {
  width: 100%;
  max-width: 280px;
  height: 14px;
  border: 2px solid var(--border);
  background: var(--bg);
}

.training-bar-fill {
  height: 100%;
  background: var(--accent);
  animation: bar-fill 3s ease-in-out infinite;
}

@keyframes bar-fill {
  0% { width: 8%; }
  85% { width: 97%; }
  100% { width: 97%; }
}

.training-label {
  color: var(--text-dim);
  font-size: 0.9rem;
}

/* ===== Inside-the-model calculation flow ===== */

.calc-flow {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 12px;
  width: 100%;
}

.calc-stage {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}

.calc-label {
  font-family: "Press Start 2P", "Courier New", monospace;
  font-size: 0.55rem;
  color: var(--accent);
}

.calc-arrow {
  margin: 0;
}

.mini-grid {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 2px;
  width: 108px;
}

.mini-px {
  aspect-ratio: 1;
}

.mini-px.dim-px {
  opacity: 0.35;
}

.mini-px.feature-hit {
  background: #6fdc8c;
  animation: feature-pulse 1.6s ease-in-out infinite;
}

@keyframes feature-pulse {
  0%, 100% { opacity: 0.6; box-shadow: 0 0 0 rgba(111, 220, 140, 0); }
  50% { opacity: 1; box-shadow: 0 0 6px 1px rgba(111, 220, 140, 0.7); }
}

.structure-svg {
  width: 108px;
  height: 108px;
}

.struct-line {
  stroke: var(--accent);
  stroke-width: 2;
}

.struct-dot {
  fill: #6fdc8c;
  animation: struct-pulse 1.8s ease-in-out infinite;
}

@keyframes struct-pulse {
  0%, 100% { opacity: 0.7; }
  50% { opacity: 1; }
}

/* ===== Landmark image ===== */

.step-hand {
  max-width: 260px;
  margin: 0;
}

/* ===== Step 4: decision flow ===== */

.decision-flow {
  text-align: center;
  width: 100%;
}

.flow-box {
  display: inline-block;
  font-family: "Press Start 2P", "Courier New", monospace;
  font-size: 0.6rem;
  background: var(--surface);
  border: 2px solid var(--border);
  padding: 10px 14px;
  color: var(--accent);
}

.flow-box.condition {
  font-family: "SF Mono", Consolas, "Courier New", monospace;
  font-size: 0.85rem;
  color: var(--text);
}

.flow-arrow {
  color: var(--accent);
  font-size: 1.2rem;
  margin: 6px 0;
}

.flow-branches {
  display: flex;
  justify-content: center;
  gap: 32px;
  margin-top: 4px;
}

.flow-branch p {
  margin: 6px 0 0;
  color: var(--text-dim);
}

.flow-box.yes {
  border-color: #6fdc8c;
  color: #6fdc8c;
}

.flow-box.no {
  border-color: #ff8a8a;
  color: #ff8a8a;
}

@media (max-width: 640px) {
  .flow-branches {
    gap: 16px;
  }
}