:root {
  --bg0: #0d0b16;
  --bg1: #1b1530;
  --bg2: #2a1d3a;
  --glass: rgba(24, 20, 38, 0.72);
  --glass-strong: rgba(20, 17, 32, 0.9);
  --line: rgba(255, 255, 255, 0.09);
  --line-strong: rgba(255, 255, 255, 0.18);
  --text: #f4efe6;
  --muted: #a69fb8;
  --accent: #ff8a1f;
  --accent-2: #ffb347;
  --green: #2fbf4a;
  --radius: 16px;
  --font: "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;
  --display: "Fredoka", "Inter", system-ui, sans-serif;
}

* { box-sizing: border-box; }
html, body { margin: 0; height: 100%; overflow: hidden; }
body {
  background: radial-gradient(120% 90% at 70% 10%, #3a2346 0%, var(--bg1) 38%, var(--bg0) 75%);
  color: var(--text);
  font: 14px/1.45 var(--font);
  -webkit-font-smoothing: antialiased;
}
button { font: inherit; color: inherit; }

#app { position: fixed; inset: 0; }
#c { position: absolute; inset: 0; width: 100%; height: 100%; display: block; touch-action: none; outline: none; }
#labels { position: absolute; inset: 0; pointer-events: none; }

/* brand */
.brand {
  position: absolute; left: 20px; top: 16px; display: flex; gap: 12px; align-items: center;
  pointer-events: none; text-shadow: 0 2px 12px rgba(0, 0, 0, 0.5);
}
.brand svg { width: 44px; height: 44px; filter: drop-shadow(0 4px 10px rgba(255, 138, 31, 0.35)); }
.brand h1 { font: 700 26px/1 var(--display); margin: 0; letter-spacing: 0.2px; }
.brand p { margin: 3px 0 0; color: var(--muted); font-size: 13px; }

/* mode switch */
#modes {
  position: absolute; left: 50%; top: 16px; transform: translateX(-50%);
  display: flex; gap: 4px; padding: 5px; border-radius: 999px;
  background: var(--glass); border: 1px solid var(--line); backdrop-filter: blur(14px); -webkit-backdrop-filter: blur(14px);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
}
#modes button {
  border: 0; background: transparent; padding: 8px 16px; border-radius: 999px; cursor: pointer;
  font-weight: 600; color: var(--muted); transition: color .2s, background .2s; white-space: nowrap;
}
#modes button:hover { color: var(--text); }
#modes button.on { background: linear-gradient(180deg, var(--accent-2), var(--accent)); color: #24130a; box-shadow: 0 4px 14px rgba(255, 138, 31, 0.45); }

/* panel */
#panel {
  position: absolute; right: 16px; top: 76px; bottom: 16px; width: 360px;
  background: var(--glass); border: 1px solid var(--line); border-radius: var(--radius);
  backdrop-filter: blur(16px); -webkit-backdrop-filter: blur(16px);
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.45);
  display: flex; flex-direction: column; transition: transform .35s cubic-bezier(.2,.8,.2,1);
}
#panelBody { overflow-y: auto; padding: 18px 18px 20px; scrollbar-width: thin; scrollbar-color: rgba(255,255,255,.2) transparent; }
#panelToggle { display: none; }
#panel h2 { font: 600 20px/1.2 var(--display); margin: 0 0 6px; }
#panel h3 { font: 600 13px/1.2 var(--font); text-transform: uppercase; letter-spacing: .08em; color: var(--muted); margin: 18px 0 8px; }
#panel p { margin: 0 0 10px; color: #d9d2e6; }
#panel .lead { color: var(--muted); }
.kbd { font-variant-numeric: tabular-nums; }

.row { display: flex; gap: 8px; align-items: center; }
.btn {
  border: 1px solid var(--line-strong); background: rgba(255,255,255,0.06); color: var(--text);
  padding: 8px 12px; border-radius: 10px; cursor: pointer; font-weight: 600; transition: background .15s, border-color .15s;
  display: inline-flex; gap: 6px; align-items: center; justify-content: center; text-decoration: none;
}
.btn:hover { background: rgba(255,255,255,0.12); }
.btn.primary { background: linear-gradient(180deg, var(--accent-2), var(--accent)); color: #24130a; border-color: transparent; }
.btn.primary:hover { filter: brightness(1.06); }
.btn.small { padding: 5px 9px; font-size: 12px; border-radius: 8px; }
.btn[disabled] { opacity: .4; cursor: default; }
.chips { display: flex; flex-wrap: wrap; gap: 6px; }

/* sliders */
.slider { display: grid; grid-template-columns: 92px 1fr 46px; gap: 10px; align-items: center; margin: 6px 0; }
.slider label { color: #d9d2e6; font-size: 13px; }
.slider output { text-align: right; color: var(--muted); font-variant-numeric: tabular-nums; font-size: 12px; }
input[type=range] { -webkit-appearance: none; appearance: none; width: 100%; height: 22px; background: transparent; cursor: pointer; }
input[type=range]::-webkit-slider-runnable-track { height: 4px; border-radius: 4px; background: linear-gradient(90deg, var(--accent) var(--p, 50%), rgba(255,255,255,.14) var(--p, 50%)); }
input[type=range]::-moz-range-track { height: 4px; border-radius: 4px; background: rgba(255,255,255,.14); }
input[type=range]::-moz-range-progress { height: 4px; border-radius: 4px; background: var(--accent); }
input[type=range]::-webkit-slider-thumb { -webkit-appearance: none; width: 16px; height: 16px; border-radius: 50%; background: #fff; margin-top: -6px; box-shadow: 0 2px 6px rgba(0,0,0,.4); }
input[type=range]::-moz-range-thumb { width: 16px; height: 16px; border: 0; border-radius: 50%; background: #fff; }

/* linkage schematic */
.schematic { width: 100%; max-height: 300px; background: rgba(0,0,0,.25); border: 1px solid var(--line); border-radius: 12px; display: block; }
.stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; margin-top: 10px; }
.stat { background: rgba(255,255,255,.05); border: 1px solid var(--line); border-radius: 10px; padding: 8px 10px; }
.stat b { display: block; font: 600 17px/1.1 var(--display); font-variant-numeric: tabular-nums; }
.stat span { color: var(--muted); font-size: 11px; }

/* parts list */
.parts { list-style: none; margin: 0; padding: 0; display: grid; gap: 6px; }
.parts li {
  display: grid; grid-template-columns: 14px 1fr auto; gap: 10px; align-items: center;
  padding: 8px 10px; border-radius: 10px; background: rgba(255,255,255,.04); border: 1px solid transparent; cursor: pointer;
}
.parts li:hover, .parts li.on { border-color: var(--line-strong); background: rgba(255,255,255,.08); }
.parts .sw { width: 14px; height: 14px; border-radius: 4px; box-shadow: inset 0 0 0 1px rgba(255,255,255,.25); }
.parts .nm { font-weight: 600; }
.parts .meta { color: var(--muted); font-size: 12px; }
.parts .qty { color: var(--accent-2); font-weight: 700; margin-left: 4px; }

.hw { background: rgba(255,255,255,.04); border: 1px solid var(--line); border-radius: 12px; padding: 10px 12px; }
.hw table { width: 100%; border-collapse: collapse; font-size: 12.5px; }
.hw td { padding: 3px 0; vertical-align: top; }
.hw td:first-child { color: var(--muted); width: 38%; }
.note { font-size: 12.5px; color: var(--muted); }

/* build steps */
.steps { list-style: none; padding: 0; margin: 0; display: grid; gap: 4px; }
.steps li { padding: 7px 10px; border-radius: 10px; cursor: pointer; color: var(--muted); display: flex; gap: 10px; }
.steps li b { width: 22px; height: 22px; flex: none; border-radius: 50%; display: grid; place-items: center; font-size: 12px; background: rgba(255,255,255,.08); color: var(--text); }
.steps li.done b { background: var(--green); color: #06210d; }
.steps li.on { background: rgba(255,138,31,.12); color: var(--text); }
.steps li.on b { background: var(--accent); color: #24130a; }
.stepcard { background: rgba(255,255,255,.05); border: 1px solid var(--line); border-radius: 12px; padding: 12px 14px; margin: 10px 0; }
.stepcard h4 { margin: 0 0 6px; font: 600 17px/1.2 var(--display); }
.stepcard ul { margin: 6px 0 0; padding-left: 18px; color: #d9d2e6; }

/* info card for a clicked part */
.info { border: 1px solid var(--line-strong); background: rgba(255,138,31,.07); border-radius: 12px; padding: 12px 14px; margin-bottom: 12px; }
.info h4 { margin: 0 0 4px; font: 600 17px/1.2 var(--display); display: flex; gap: 8px; align-items: center; }
.info .sw { width: 12px; height: 12px; border-radius: 3px; display: inline-block; }

/* floating tools */
#tools { position: absolute; left: 20px; bottom: 20px; display: flex; gap: 8px; }
#tools button {
  border: 1px solid var(--line); background: var(--glass); backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
  padding: 8px 14px; border-radius: 999px; cursor: pointer; font-weight: 600; color: var(--muted);
}
#tools button:hover { color: var(--text); }
#tools button.on { color: #071b2e; background: #7fd3ff; border-color: transparent; }

#tip {
  position: absolute; pointer-events: none; padding: 6px 10px; border-radius: 8px; font-size: 12.5px; font-weight: 600;
  background: var(--glass-strong); border: 1px solid var(--line-strong); opacity: 0; transform: translate(12px, 12px); transition: opacity .12s;
  white-space: nowrap;
}
#hint { position: absolute; left: 50%; bottom: 18px; transform: translateX(-50%); color: rgba(255,255,255,.45); font-size: 12px; pointer-events: none; }

/* labels in 3D */
.lbl {
  pointer-events: auto; background: var(--glass-strong); border: 1px solid var(--line-strong); border-radius: 10px;
  padding: 6px 9px 7px; font-size: 12px; line-height: 1.25; white-space: nowrap; box-shadow: 0 6px 18px rgba(0,0,0,.4);
  transform: translateY(-14px); transition: opacity .25s;
}
.lbl b { display: flex; align-items: center; gap: 6px; font-size: 12.5px; }
.lbl i { width: 9px; height: 9px; border-radius: 2px; display: inline-block; }
.lbl span { color: var(--muted); }
.lbl a { color: var(--accent-2); font-weight: 700; text-decoration: none; margin-left: 6px; }
.lbl a:hover { text-decoration: underline; }
.lbl.plain { pointer-events: none; padding: 4px 8px; }
.lbl.hide { opacity: 0; pointer-events: none; }

/* loader */
#loader { position: absolute; inset: 0; display: grid; place-content: center; justify-items: center; gap: 14px; background: var(--bg0); transition: opacity .6s; z-index: 5; }
#loader.done { opacity: 0; pointer-events: none; }
#loader .ring { width: 44px; height: 44px; border-radius: 50%; border: 3px solid rgba(255,255,255,.1); border-top-color: var(--accent); animation: spin 1s linear infinite; }
#loader .bar { width: 220px; height: 4px; border-radius: 4px; background: rgba(255,255,255,.08); overflow: hidden; }
#loader .bar i { display: block; height: 100%; width: 0; background: var(--accent); transition: width .2s; }
#loadText { color: var(--muted); }
@keyframes spin { to { transform: rotate(360deg); } }

@media (max-width: 860px) {
  .brand { top: 12px; left: 14px; }
  .brand svg { width: 34px; height: 34px; }
  .brand h1 { font-size: 20px; }
  .brand p { display: none; }
  #modes { top: 62px; left: 12px; right: 12px; transform: none; overflow-x: auto; justify-content: space-between; scrollbar-width: none; }
  #modes button { padding: 7px 12px; font-size: 13px; }
  #panel { left: 0; right: 0; top: auto; bottom: 0; width: auto; height: 46vh; border-radius: 18px 18px 0 0; border-bottom: 0; }
  #panel.min { transform: translateY(calc(100% - 38px)); }
  #panelToggle { display: block; position: absolute; left: 50%; top: 0; transform: translateX(-50%); width: 80px; height: 30px; border: 0; background: transparent; cursor: pointer; }
  #panelToggle span { display: block; width: 40px; height: 4px; border-radius: 4px; background: rgba(255,255,255,.35); margin: 0 auto; }
  #panelBody { padding: 26px 16px 18px; }
  #tools { left: auto; right: 12px; bottom: calc(46vh + 10px); }
  #panel.min ~ #tools { bottom: 50px; }
  #hint { display: none; }
}