:root{--bg:#0b1220;--panel:#111a2e;--panel2:#16213a;--line:#223052;--text:#dbe4f5;--dim:#8a9ac0;--cyan:#22d3ee;--amber:#fbbf24;--green:#34d399;--red:#f87171}
*{box-sizing:border-box}
html,body{margin:0;height:100%;background:var(--bg);color:var(--text);font:13px/1.35 system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;font-variant-numeric:tabular-nums}
.mono{font-family:ui-monospace,"SF Mono",Menlo,Consolas,monospace}
body{display:flex;flex-direction:column;height:100vh;height:100dvh;overflow:hidden}
#topbar{display:flex;align-items:center;gap:12px;padding:6px 14px;background:var(--panel);border-bottom:1px solid var(--line);flex:none}
.titles{flex:1;min-width:0}
h1{font-size:16px;margin:0;font-weight:650;letter-spacing:.01em;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.subtitle{margin:0;color:var(--dim);font-size:11.5px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.icon-btn{background:var(--panel2);color:var(--cyan);border:1px solid var(--line);border-radius:8px;width:32px;height:32px;font-size:15px;cursor:pointer}
.icon-btn:hover{border-color:var(--cyan)}
#error-banner{background:#5b1a1a;color:#ffd6d6;padding:6px 14px;font:12px ui-monospace,monospace;white-space:pre-wrap;border-bottom:2px solid var(--red);max-height:25vh;overflow:auto}
#error-banner[hidden]{display:none}
#app{flex:1;display:flex;min-height:0}
#panel{width:330px;flex:none;overflow-y:auto;background:var(--panel);border-right:1px solid var(--line);padding:10px;scrollbar-width:thin;scrollbar-color:#2c3d68 transparent}
body.panel-hidden #panel{display:none}
#center{flex:1;display:flex;flex-direction:column;min-width:0}
#viewport{position:relative;flex:1;min-height:200px;background:radial-gradient(ellipse at 50% 30%,#14213d,#0b1220);overflow:hidden}
#viewport canvas{display:block}
#readout{position:absolute;top:8px;left:8px;background:rgba(11,18,32,.78);border:1px solid var(--line);border-radius:8px;padding:6px 9px;font-size:11.5px;line-height:1.5;pointer-events:none;min-width:150px;z-index:2}
#readout .row{display:flex;justify-content:space-between;gap:12px}
#readout .k{color:var(--dim)}
.pbar{height:6px;background:#2a3a63;border-radius:3px;margin:3px 0;overflow:hidden}
.pbar i{display:block;height:100%;background:var(--cyan);width:50%}
.badge{display:inline-block;background:var(--red);color:#fff;border-radius:4px;padding:0 6px;font-weight:700;margin-top:3px}
#vp-tools{position:absolute;left:8px;bottom:8px;display:flex;gap:6px;z-index:2}
#toast{position:absolute;left:50%;top:12px;transform:translateX(-50%);background:#1b2a4d;border:1px solid var(--cyan);color:var(--text);padding:8px 14px;border-radius:8px;max-width:80%;z-index:5;box-shadow:0 4px 18px rgba(0,0,0,.5)}
#toast.warn{border-color:var(--amber);background:#3a2e10}
#toast[hidden]{display:none}
#charts{flex:none;height:min(240px,32vh);display:grid;grid-template-columns:1fr 1.6fr .9fr 1.2fr;gap:6px;padding:6px;background:var(--bg);border-top:1px solid var(--line)}
.chartbox{position:relative;min-width:0;min-height:0;background:var(--panel);border:1px solid var(--line);border-radius:8px;overflow:hidden}
.chartbox canvas{position:absolute;inset:0;width:100%;height:100%}
.btn{background:var(--panel2);color:var(--text);border:1px solid var(--line);border-radius:6px;padding:5px 10px;font:inherit;cursor:pointer}
.btn:hover{border-color:var(--cyan);color:#fff}
.btn.accent{background:#0e3a46;border-color:#1b7c92;color:#c8f6ff}
.btn.sm{padding:3px 8px;font-size:12px}
.btnrow{display:flex;flex-wrap:wrap;gap:6px;margin:6px 0}
/* panel */
.group{border:1px solid var(--line);border-radius:8px;margin:8px 0;background:#0e1730}
.group>summary{cursor:pointer;padding:7px 10px;font-weight:600;color:var(--cyan);list-style:none;user-select:none}
.group>summary::before{content:"▸ ";color:var(--dim)}
.group[open]>summary::before{content:"▾ "}
.group>summary::-webkit-details-marker{display:none}
.group .body{padding:2px 10px 10px}
.ctl{margin:7px 0}
.ctl .lab{display:flex;justify-content:space-between;align-items:center;gap:6px;color:var(--dim);font-size:12px}
.ctl .lab span.u{color:#5f709a}
.ctl .inp{display:flex;gap:8px;align-items:center}
.ctl input[type=range]{flex:1;min-width:0;accent-color:var(--cyan)}
.ctl input[type=number]{width:74px;background:#0b1220;color:var(--text);border:1px solid var(--line);border-radius:5px;padding:3px 5px;font:inherit}
.ctl select,.sel{width:100%;background:#0b1220;color:var(--text);border:1px solid var(--line);border-radius:5px;padding:4px;font:inherit}
.ctl.check label{display:flex;gap:8px;align-items:center;color:var(--text)}
.info{display:flex;justify-content:space-between;padding:4px 8px;background:#0b1220;border-radius:5px;color:var(--dim)}
.info b{color:var(--text)}
/* segmented control, notes, sub-sections */
.seg{display:flex;border:1px solid var(--line);border-radius:7px;overflow:hidden;margin:6px 0}
.seg button{flex:1;background:#0b1220;color:var(--dim);border:0;border-right:1px solid var(--line);padding:5px 6px;font:inherit;font-size:12px;cursor:pointer}
.seg button:last-child{border-right:0}
.seg button:hover{color:#fff}
.seg button.on{background:#0e3a46;color:#c8f6ff;font-weight:600;box-shadow:inset 0 -2px 0 var(--cyan)}
.model-seg{margin:0 0 4px}
.model-note{margin:2px 0 8px;color:var(--dim);font-size:11.5px;line-height:1.35}
.note{color:var(--amber);font-size:11.5px;margin:6px 0;line-height:1.35}
.sub>details{border-top:1px dashed var(--line);margin-top:6px}
.sub>details>summary{cursor:pointer;color:var(--dim);padding:5px 0;font-size:12px;user-select:none}
.sub>details>.body{padding:0}
.tgrid .sec{font-size:11.5px}
.inertia{margin-top:4px;color:var(--dim);font-size:11px}
/* tuning */
#tuning{background:var(--panel2);border:1px solid #2a3d6b;border-radius:10px;padding:10px}
#tuning h3{margin:0 0 6px;font-size:12px;letter-spacing:.08em;text-transform:uppercase;color:var(--amber)}
.tgrid{display:grid;grid-template-columns:1fr 1fr;gap:3px 12px}
.tgrid div{display:flex;justify-content:space-between;color:var(--dim)}
.tgrid b{color:var(--text);font-weight:600}
.gauge{position:relative;height:22px;margin:10px 2px 4px;background:#0b1220;border:1px solid var(--line);border-radius:5px}
.gauge .band{position:absolute;top:0;bottom:0;background:rgba(52,211,153,.35);border-left:1px solid var(--green);border-right:1px solid var(--green)}
.gauge .mid{position:absolute;top:-3px;bottom:-3px;width:2px;background:var(--green);left:50%}
.gauge .mark{position:absolute;top:-4px;width:4px;bottom:-4px;margin-left:-2px;background:var(--amber);border-radius:2px;box-shadow:0 0 6px var(--amber)}
.gauge .mark.ok{background:var(--green);box-shadow:0 0 6px var(--green)}
.glab{display:flex;justify-content:space-between;font-size:10px;color:var(--dim);margin:0 2px}
.warns{margin:6px 0 0;padding:0 0 0 16px;color:var(--amber);font-size:12px}
.warns:empty{display:none}
dialog{background:var(--panel);color:var(--text);border:1px solid var(--cyan);border-radius:12px;max-width:640px;padding:18px 22px;line-height:1.5}
dialog::backdrop{background:rgba(0,0,0,.6)}
dialog h2{margin-top:0;color:var(--cyan)}
@media (max-width:1250px){
  #charts{grid-template-columns:1fr 1fr;grid-template-rows:1fr 1fr;height:min(420px,48vh)}
}
@media (min-width:900px) and (max-width:1250px) and (min-height:700px){}
@media (max-width:900px){
  body{overflow:auto;height:auto}
  #app{flex-direction:column}
  #center{order:1}
  #panel{order:2;width:auto;border-right:0;border-top:1px solid var(--line);overflow:visible}
  #viewport{flex:none;height:62vh;min-height:300px}
  #charts{grid-template-columns:1fr;grid-template-rows:none;height:auto}
  .chartbox{height:230px}
  h1{font-size:13px;white-space:normal}
  #readout{font-size:10px;line-height:1.3;padding:4px 6px;min-width:120px}
  .subtitle{display:none}
}
/* v3 additions */
dialog#help{width:min(780px,94vw);max-height:90vh;max-height:90dvh;padding:0;overflow:hidden}
dialog#help[open]{display:flex;flex-direction:column}
.help-head{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:10px 20px;border-bottom:1px solid var(--line);background:var(--panel2);flex:none}
.help-head h2{margin:0}
.help-head form{margin:0}
.help-body{overflow-y:auto;padding:4px 20px 18px;-webkit-overflow-scrolling:touch}
.help-body h3{color:var(--amber);margin:18px 0 4px;font-size:15px}
.help-body h4{color:var(--cyan);margin:14px 0 2px;font-size:13.5px}
.help-body .eq{overflow-x:auto;overflow-y:hidden;margin:4px 0;max-width:100%}
.help-body .eq .katex-display{margin:.4em 0}
.help-body .hnote{color:var(--dim);font-size:12px}
.help-body p{margin:6px 0}
.dbox{background:#0b1220;border:1px solid var(--line);border-radius:6px;padding:6px 8px;font-size:11.5px}
.dbox-t{color:var(--dim);margin-bottom:3px;font-family:system-ui,sans-serif}
.dbox .r{display:flex;justify-content:space-between;gap:8px}
.dbox .r b{color:var(--text);font-weight:600}
.spin{display:inline-block;width:11px;height:11px;border:2px solid var(--dim);border-top-color:var(--cyan);border-radius:50%;animation:sp .8s linear infinite;vertical-align:-2px;margin-right:4px}
@keyframes sp{to{transform:rotate(360deg)}}
.btn[disabled]{opacity:.5;cursor:default}
#resonance{background:var(--panel2);border:1px solid #2a3d6b;border-radius:10px;padding:10px;margin-top:8px}
#resonance>summary{cursor:pointer;font-size:12px;letter-spacing:.06em;text-transform:uppercase;color:var(--amber);font-weight:600;list-style:none}
#resonance>summary::-webkit-details-marker{display:none}
#resonance .row2{display:flex;gap:6px;align-items:center;margin:6px 0}
#resonance .row2 label{color:var(--dim);font-size:12px;flex:none}
#resonance select,#resonance input[type=number]{background:#0b1220;color:var(--text);border:1px solid var(--line);border-radius:5px;padding:3px 5px;font:inherit;min-width:0}
#resonance select{flex:1}
#resonance input[type=number]{width:64px}
.progress{height:6px;background:#2a3a63;border-radius:3px;overflow:hidden;margin:4px 0}
.progress i{display:block;height:100%;width:0;background:var(--green);transition:width .2s}
#scan-box{height:150px;position:relative;background:#0b1220;border:1px solid var(--line);border-radius:6px;margin:6px 0}
#scan-box canvas{position:absolute;inset:0;width:100%;height:100%}
.res-out{font-size:12px;color:var(--dim);margin:4px 0;line-height:1.5}
.res-out b{color:var(--text)}
.res-why{font-size:11.5px;color:var(--dim);margin:6px 0 0;line-height:1.35}
#t-compute{color:var(--amber);font-size:11.5px;margin:2px 0 0}
@media (max-width:900px){ dialog#help{width:96vw;max-height:94dvh} .help-body{padding:4px 12px 14px} }

.chart-sel{position:absolute;top:2px;left:6px;max-width:calc(100% - 12px);height:17px;background:#0b1220;color:var(--text);border:1px solid var(--line);border-radius:5px;padding:0 2px;font:600 10.5px system-ui,sans-serif}