:root {
  --bg: #0b0d10; --panel: rgba(16,19,24,0.88); --panel-solid: #12151b;
  --line: #262b33; --txt: #d7dbe2; --txt-dim: #8b93a0; --accent: #3d8bfd;
  --accent2: #e8b23c; --mono: "SF Mono", "Cascadia Code", Consolas, monospace;
}
* { box-sizing: border-box; }
html, body { margin: 0; height: 100%; overflow: hidden; background: var(--bg); }
body { font-family: "Avenir Next", "Segoe UI", system-ui, sans-serif; color: var(--txt); font-size: 14px; }
#app { position: fixed; inset: 0; }
#stage { position: absolute; inset: 0; width: 100%; height: 100%; display: block; cursor: grab; }
#stage:active { cursor: grabbing; }

/* loader */
#loader { position: absolute; inset: 0; display: grid; place-items: center; background: var(--bg); z-index: 50; transition: opacity .4s; }
#loader.done { opacity: 0; pointer-events: none; }
.loader-card { text-align: center; width: min(340px, 80vw); }
.loader-badge { font-size: 11px; letter-spacing: .3em; color: var(--txt-dim); }
.loader-card h1 { font-weight: 600; font-size: 30px; margin: 10px 0 24px; letter-spacing: .02em; }
.loader-bar { height: 3px; background: #232830; border-radius: 2px; overflow: hidden; }
#loader-fill { height: 100%; width: 0; background: var(--accent); transition: width .2s; }
#loader-msg { margin-top: 12px; color: var(--txt-dim); font-size: 12px; }

/* top bar */
#topbar { position: absolute; top: 0; left: 0; right: 0; display: flex; align-items: center; gap: 12px; padding: 10px 14px; z-index: 20; background: linear-gradient(#0b0d10cc, transparent); pointer-events: none; }
#topbar > * { pointer-events: auto; }
.title-block .title { font-size: 17px; font-weight: 650; letter-spacing: .02em; }
.title-block .gen { color: var(--txt-dim); font-weight: 500; font-size: 12px; margin-left: 6px; }
.subtitle { font-size: 11.5px; color: var(--txt-dim); margin-top: 1px; }
.plate { font-family: var(--mono); background: #f0f0ea; color: #111; border-radius: 3px; padding: 0 5px; font-weight: 700; font-size: 11px; }
.top-spacer { flex: 1; }
.icon-btn { width: 34px; height: 34px; border-radius: 8px; border: 1px solid var(--line); background: var(--panel); color: var(--txt); font-size: 16px; cursor: pointer; }
.icon-btn:hover { border-color: var(--accent); }

/* side panels */
.panel { position: absolute; top: 58px; bottom: 92px; width: 292px; background: var(--panel); backdrop-filter: blur(10px); border: 1px solid var(--line); border-radius: 12px; display: flex; flex-direction: column; z-index: 15; transition: transform .28s ease; }
#sidebar { left: 12px; }
#infopanel { right: 12px; width: 300px; }
.panel-head { padding: 12px 14px 8px; border-bottom: 1px solid var(--line); }
.panel-head h2 { margin: 0 0 8px; font-size: 13px; font-weight: 650; letter-spacing: .04em; text-transform: uppercase; color: var(--txt-dim); }
.panel-foot { padding: 8px 14px; border-top: 1px solid var(--line); font-size: 11px; color: var(--txt-dim); }
#part-search { width: 100%; background: #0d1014; border: 1px solid var(--line); color: var(--txt); border-radius: 7px; padding: 7px 10px; font-size: 13px; outline: none; }
#part-search:focus { border-color: var(--accent); }

.group-tree { flex: 1; overflow-y: auto; padding: 6px 8px 12px; }
.grp { border-bottom: 1px solid #1d2129; }
.grp summary { cursor: pointer; list-style: none; padding: 9px 8px; font-size: 13.5px; font-weight: 600; display: flex; align-items: center; gap: 8px; border-radius: 6px; }
.grp summary::-webkit-details-marker { display: none; }
.grp summary:hover { background: #1a1f27; }
.grp summary::after { content: '›'; margin-left: auto; color: var(--txt-dim); transition: transform .15s; }
.grp[open] summary::after { transform: rotate(90deg); }
.g-ic { color: var(--accent); width: 16px; text-align: center; }
.g-count { color: var(--txt-dim); font-size: 11px; font-weight: 500; background: #1c212a; padding: 1px 7px; border-radius: 8px; }
.grp-body { padding: 2px 4px 10px 12px; }
.grp-info { display: block; width: 100%; text-align: left; background: none; border: none; color: var(--accent); font-size: 12px; padding: 4px 8px; cursor: pointer; }
.part-row { display: flex; align-items: center; gap: 8px; width: 100%; text-align: left; background: none; border: none; color: var(--txt); font-size: 12.5px; padding: 5px 8px; border-radius: 6px; cursor: pointer; }
.part-row:hover { background: #1c222c; }
.part-row.sel { background: #1e3350; color: #cfe2ff; }
.part-row .dot { width: 5px; height: 5px; border-radius: 50%; background: #39404c; flex: none; }
.part-row.sel .dot { background: var(--accent); }

/* info panel */
#info-body { flex: 1; overflow-y: auto; padding: 14px; font-size: 13.5px; line-height: 1.5; }
#info-body p { margin: 10px 0; color: var(--txt); }
.tag-row { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 4px; }
.tag { font-size: 10.5px; letter-spacing: .05em; text-transform: uppercase; background: #1c222c; color: var(--txt-dim); padding: 3px 8px; border-radius: 4px; }
.tag.ref { color: #7fd4a8; } .tag.rep { color: #e8b23c; }
.tag.plate { font-family: var(--mono); background: #f0f0ea; color: #111; font-weight: 700; }
.spec { margin: 12px 0; border-top: 1px solid var(--line); }
.spec dt { color: var(--txt-dim); font-size: 11px; text-transform: uppercase; letter-spacing: .06em; margin-top: 10px; }
.spec dd { margin: 2px 0 0; font-size: 13.5px; }
.fine { color: var(--txt-dim); font-size: 12px !important; }
.btn-row { display: flex; gap: 8px; margin-top: 16px; flex-wrap: wrap; }
.ctl-btn { background: #1c222c; border: 1px solid var(--line); color: var(--txt); border-radius: 8px; padding: 8px 14px; font-size: 13px; cursor: pointer; }
.ctl-btn:hover { border-color: var(--accent); }
.ctl-btn.accent { background: #1d4f9e; border-color: #2f6fd0; color: #fff; }
.ctl-btn.small { padding: 6px 10px; font-size: 12px; }
.ctl-btn.on { border-color: var(--accent); color: var(--accent); }

/* hint bar */
#hint { position: absolute; left: 50%; transform: translateX(-50%); bottom: 66px; display: flex; gap: 16px; font-size: 11px; color: var(--txt-dim); background: rgba(12,14,18,.6); padding: 5px 14px; border-radius: 8px; z-index: 10; pointer-events: none; white-space: nowrap; }
#hint b { color: var(--txt); font-weight: 600; }

/* dock */
#dock { position: absolute; left: 50%; transform: translateX(-50%); bottom: 14px; z-index: 20; width: min(660px, calc(100vw - 24px)); }
.dock-row { display: flex; align-items: center; gap: 10px; background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 9px 12px; backdrop-filter: blur(10px); }
.slider-wrap { flex: 1; display: flex; align-items: center; gap: 8px; }
#explode-slider { flex: 1; -webkit-appearance: none; appearance: none; height: 4px; background: linear-gradient(90deg, var(--accent) var(--p,0%), #262b33 var(--p,0%)); border-radius: 2px; outline: none; }
#explode-slider::-webkit-slider-thumb { -webkit-appearance: none; width: 22px; height: 22px; border-radius: 50%; background: #e8ecf2; border: 3px solid var(--accent); cursor: ew-resize; }
#explode-slider::-moz-range-thumb { width: 18px; height: 18px; border-radius: 50%; background: #e8ecf2; border: 3px solid var(--accent); cursor: ew-resize; }
#piece-counter { font-family: var(--mono); font-size: 12px; color: var(--txt-dim); white-space: nowrap; }
#piece-num { color: var(--accent2); font-weight: 700; }
.keys-row { margin-top: 8px; justify-content: center; gap: 8px; padding: 6px 10px; display: none; }
.dir-btn { width: 40px; height: 34px; border-radius: 8px; border: 1px solid var(--line); background: #171b22; color: var(--txt); font-size: 14px; cursor: pointer; }
.dir-btn:active { background: #254069; }

/* help overlay */
#help-overlay { position: absolute; inset: 0; background: rgba(5,6,8,.7); display: grid; place-items: center; z-index: 40; }
#help-overlay[hidden] { display: none; }
.help-card { background: var(--panel-solid); border: 1px solid var(--line); border-radius: 14px; padding: 22px 26px; width: min(430px, 88vw); }
.help-card h3 { margin: 0 0 12px; font-size: 16px; }
.help-card ul { margin: 0 0 16px; padding: 0; list-style: none; }
.help-card li { padding: 5px 0; font-size: 13.5px; color: var(--txt); }
kbd { background: #232830; border: 1px solid #343b46; border-bottom-width: 2px; border-radius: 4px; padding: 1px 6px; font-family: var(--mono); font-size: 11px; }

/* responsive */
@media (max-width: 1024px) {
  .panel { top: auto; bottom: 0; width: 100%; max-height: 46vh; border-radius: 16px 16px 0 0; border-bottom: none; }
  #sidebar { left: 0; transform: translateY(105%); }
  #infopanel { right: 0; transform: translateY(105%); }
  body.nav-open #sidebar { transform: translateY(0); }
  body.info-open #infopanel { transform: translateY(0); }
  #hint { display: none; }
  .keys-row { display: flex; }
}
@media (min-width: 1025px) {
  #sidebar { transform: translateX(-108%); transition: transform .28s; }
  body.nav-open #sidebar { transform: none; }
  #infopanel { transform: translateX(108%); transition: transform .28s; }
  body.info-open #infopanel { transform: none; }
}
@media (max-width: 560px) {
  .title-block .title { font-size: 14px; }
  .subtitle { font-size: 10px; }
  #dock { bottom: 8px; }
  .dock-row { flex-wrap: wrap; }
  #piece-counter { width: 100%; text-align: center; }
}