*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #0a0a0f;
  --surface: #13131a;
  --surface2: #1c1c27;
  --accent: #6c63ff;
  --accent2: #a78bfa;
  --orange: #f97316;
  --orange2: #fb923c;
  --success: #34d399;
  --error: #f87171;
  --text: #e2e8f0;
  --muted: #64748b;
  --border: #2a2a3d;
  --radius: 12px;
}

html { scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
}

/* Header */
header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 1.2rem 2rem;
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 200;
  background: rgba(10,10,15,0.92);
  backdrop-filter: blur(12px);
}
.logo { font-size: 1.3rem; font-weight: 700; color: var(--accent2); letter-spacing: -0.02em; }
nav { display: flex; gap: 1.5rem; }
nav a { color: var(--muted); text-decoration: none; font-size: 0.9rem; transition: color .2s; }
nav a:hover { color: var(--text); }

/* Steps */
main { width: 100%; }
.step { display: none; }
.step.active { display: block; }

/* Step 1: Upload */
#step-upload { max-width: 800px; margin: 0 auto; padding: 2rem 1.5rem 4rem; }
.hero { text-align: center; padding: 3.5rem 0 2.5rem; }
.hero h1 { font-size: clamp(1.8rem, 4vw, 3rem); font-weight: 800; line-height: 1.15; letter-spacing: -0.03em; margin-bottom: 1rem; }
.hero h1 span { background: linear-gradient(135deg, var(--accent), var(--accent2)); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }
.subtitle { color: var(--muted); font-size: 1rem; max-width: 500px; margin: 0 auto; }

.drop-zone {
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  padding: 3.5rem 2rem;
  text-align: center;
  cursor: pointer;
  transition: border-color .2s, background .2s;
  background: var(--surface);
  margin-top: 1.5rem;
}
.drop-zone:hover, .drop-zone.over { border-color: var(--accent); background: rgba(108,99,255,.06); }
.drop-icon { font-size: 2.8rem; margin-bottom: 1rem; }
.drop-title { font-size: 1.1rem; font-weight: 600; margin-bottom: .4rem; }
.drop-sub { color: var(--muted); font-size: .9rem; margin-bottom: .8rem; }
.browse-link { color: var(--accent2); cursor: pointer; text-decoration: underline; }
.drop-formats { font-size: .78rem; color: var(--muted); letter-spacing: .04em; }

/* Status card (steps 2 & 4) */
#step-converting, #step-rigging {
  display: none;
  min-height: 60vh;
  align-items: center;
  justify-content: center;
}
#step-converting.active, #step-rigging.active { display: flex; }

.status-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 3rem 2.5rem;
  text-align: center;
  width: 100%;
  max-width: 480px;
  margin: 2rem auto;
}
.spinner {
  width: 52px; height: 52px;
  border: 3px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin .8s linear infinite;
  margin: 0 auto 1.4rem;
}
@keyframes spin { to { transform: rotate(360deg); } }
.status-title { font-size: 1.1rem; font-weight: 600; margin-bottom: .5rem; }
.status-sub { font-size: .88rem; color: var(--muted); margin-bottom: 1.4rem; }
.progress-bar { height: 4px; background: var(--surface2); border-radius: 99px; overflow: hidden; }
.progress-fill { height: 100%; background: linear-gradient(90deg, var(--accent), var(--accent2)); border-radius: 99px; transition: width .5s ease; }

/* Step 3: Joints */
#step-joints { display: none; height: calc(100vh - 60px); }
#step-joints.active { display: flex; flex-direction: column; }
.joints-layout {
  display: grid;
  grid-template-columns: 1fr 300px;
  flex: 1;
  overflow: hidden;
}
.viewer-wrap { position: relative; background: #080810; overflow: hidden; }
#previewCanvas, #resultCanvas { width: 100% !important; height: 100% !important; display: block; }
.viewer-hint {
  position: absolute; bottom: 12px; left: 50%; transform: translateX(-50%);
  background: rgba(0,0,0,.6); color: var(--muted);
  padding: .4rem 1rem; border-radius: 99px; font-size: .75rem;
  white-space: nowrap; pointer-events: none;
}

.joints-panel {
  background: var(--surface);
  border-left: 1px solid var(--border);
  padding: 1.2rem;
  display: flex; flex-direction: column; gap: .7rem;
  overflow-y: auto;
}
.joints-panel h3 { font-size: .9rem; font-weight: 700; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); }
.joints-desc { font-size: .8rem; color: var(--muted); line-height: 1.5; }

/* Mode selector */
.mode-group { display: flex; gap: .4rem; }
.mode-btn {
  flex: 1; padding: .45rem .3rem;
  background: var(--surface2); border: 1px solid var(--border);
  color: var(--muted); border-radius: 7px; font-size: .78rem;
  cursor: pointer; transition: all .15s; text-align: center;
}
.mode-btn:hover { border-color: var(--accent2); color: var(--text); }
.mode-btn.active { background: rgba(108,99,255,.18); border-color: var(--accent); color: var(--accent2); font-weight: 600; }

/* Mirror toggle */
.option-row { display: flex; align-items: center; }
.toggle-label {
  display: flex; align-items: center; gap: .6rem;
  font-size: .82rem; color: var(--text); cursor: pointer; user-select: none;
}
.toggle-label input { display: none; }
.toggle-track {
  width: 34px; height: 18px; background: var(--surface2);
  border: 1px solid var(--border); border-radius: 99px;
  position: relative; transition: background .2s;
}
.toggle-label input:checked ~ .toggle-track { background: var(--accent); border-color: var(--accent); }
.toggle-thumb {
  position: absolute; top: 2px; left: 2px;
  width: 12px; height: 12px; border-radius: 50%;
  background: var(--muted); transition: transform .2s, background .2s;
}
.toggle-label input:checked ~ .toggle-track .toggle-thumb {
  transform: translateX(16px); background: #fff;
}
.joints-list { display: flex; flex-direction: column; gap: .3rem; flex: 1; }
.joint-item {
  display: flex; align-items: center; gap: .6rem;
  padding: .45rem .7rem;
  border-radius: 6px;
  font-size: .82rem;
  cursor: pointer;
  border: 1px solid transparent;
  transition: background .15s, border-color .15s;
}
.joint-item:hover { background: var(--surface2); }
.joint-item.selected { background: rgba(249,115,22,.1); border-color: var(--orange); }
.joint-dot {
  width: 10px; height: 10px; border-radius: 50%;
  background: var(--orange); flex-shrink: 0;
}
.joint-item.selected .joint-dot { background: var(--orange2); box-shadow: 0 0 6px var(--orange); }

/* Step 5: Result */
#step-result { display: none; height: calc(100vh - 60px); }
#step-result.active { display: flex; flex-direction: column; }
.result-layout {
  display: grid;
  grid-template-columns: 1fr 300px;
  flex: 1;
  overflow: hidden;
}
.anim-controls {
  position: absolute; bottom: 16px; left: 50%; transform: translateX(-50%);
  display: flex; gap: .5rem;
}
.anim-btn {
  background: rgba(0,0,0,.7); color: var(--muted);
  border: 1px solid var(--border); padding: .4rem 1rem;
  border-radius: 6px; font-size: .82rem; cursor: pointer;
  transition: all .2s;
}
.anim-btn:hover { border-color: var(--accent); color: var(--text); }
.anim-btn.active { background: var(--accent); border-color: var(--accent); color: #fff; }

.result-panel {
  background: var(--surface);
  border-left: 1px solid var(--border);
  padding: 1.8rem 1.5rem;
  display: flex; flex-direction: column; gap: 1rem;
  overflow-y: auto;
}
.result-badge {
  display: inline-flex; align-items: center; gap: .4rem;
  background: rgba(52,211,153,.1); color: var(--success);
  border: 1px solid rgba(52,211,153,.3);
  padding: .35rem .9rem; border-radius: 99px; font-size: .82rem; font-weight: 600;
  width: fit-content;
}
.result-panel h3 { font-size: 1.05rem; font-weight: 700; }
.result-panel p { font-size: .85rem; color: var(--muted); line-height: 1.5; }
.result-stats { font-size: .78rem; color: var(--muted); margin-top: auto; padding-top: 1rem; border-top: 1px solid var(--border); }

/* Buttons */
.btn-primary {
  width: 100%; padding: .85rem 1.5rem;
  background: linear-gradient(135deg, var(--accent), var(--accent2));
  color: #fff; border: none; border-radius: 8px;
  font-size: .95rem; font-weight: 600; cursor: pointer;
  transition: opacity .2s, transform .15s;
}
.btn-primary:hover { opacity: .9; transform: translateY(-1px); }
.btn-secondary {
  width: 100%; padding: .7rem 1.5rem;
  background: none; color: var(--muted);
  border: 1px solid var(--border); border-radius: 8px;
  font-size: .88rem; cursor: pointer;
  transition: border-color .2s, color .2s;
}
.btn-secondary:hover { border-color: var(--text); color: var(--text); }

/* Info sections */
.info-section { border-top: 1px solid var(--border); padding: 3.5rem 1.5rem; }
.info-inner { max-width: 860px; margin: 0 auto; }
h2 { font-size: 1.5rem; font-weight: 700; margin-bottom: 2rem; letter-spacing: -0.02em; }
.steps-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 1.2rem; }
.step-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 1.4rem; }
.step-num { width: 32px; height: 32px; background: linear-gradient(135deg, var(--accent), var(--accent2)); border-radius: 7px; display: flex; align-items: center; justify-content: center; font-weight: 700; font-size: .85rem; margin-bottom: .8rem; }
.step-card h4 { font-size: .95rem; margin-bottom: .3rem; }
.step-card p { font-size: .82rem; color: var(--muted); }
.format-grid { display: flex; flex-wrap: wrap; gap: .5rem; }
.fmt { background: var(--surface2); border: 1px solid var(--border); border-radius: 6px; padding: .35rem .8rem; font-size: .8rem; font-family: monospace; color: var(--accent2); }

footer { text-align: center; padding: 2rem; border-top: 1px solid var(--border); font-size: .8rem; color: var(--muted); }
footer a { color: var(--accent2); text-decoration: none; }

@media (max-width: 700px) {
  .joints-layout, .result-layout { grid-template-columns: 1fr; grid-template-rows: 60vh auto; }
  .joints-panel, .result-panel { height: auto; overflow-y: visible; }
}