/* =============================================================================
 *  OCL — design system
 *  Swiss / International Typographic Style with MIT identity: white paper,
 *  near-black ink, MIT maroon, one signal red. A single centered column,
 *  generous margins, one cohesive instrument panel, mono for data.
 * ========================================================================== */
:root {
  --paper:    #ffffff;
  --paper-2:  #faf9f7;
  --paper-3:  #efece8;
  --ink:      #0f0f0f;
  --ink-2:    #353535;
  --ink-3:    #6f6f6f;
  --ink-4:    #9a9a9a;
  --hair:     #ebe8e3;
  --hair-2:   #dcd8d1;
  --mit:      #750014;   /* MIT maroon (brand) */
  --mit-2:    #8a1f2b;
  --accent:   #e2231a;   /* signal red — the period, the next probe */
  --detect:   #750014;
  --ok:       #1f7a4d;

  --sans: "Helvetica Neue", Helvetica, Arial, "Segoe UI", Roboto, sans-serif;
  --mono: "SF Mono", ui-monospace, "JetBrains Mono", "Cascadia Code", Menlo, Consolas, monospace;

  --colw: 880px;
  --r: 6px;
  --r-lg: 14px;
  --shadow: 0 1px 2px rgba(15,15,15,.04), 0 18px 40px -22px rgba(15,15,15,.28);
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background:
    radial-gradient(1100px 520px at 84% -8%, rgba(117,0,20,.045), transparent 62%),
    var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
::selection { background: rgba(117,0,20,.14); }
.mono { font-family: var(--mono); font-variant-numeric: tabular-nums; }

.page { max-width: var(--colw); margin: 0 auto; padding: 0 40px 96px; }
@media (max-width: 720px){ .page { padding: 0 20px 64px; } }

/* ---- hero --------------------------------------------------------------- */
.hero { padding: 84px 0 40px; }
.hero .dot-accent {
  width: 30px; height: 30px; border-radius: 50%; background: var(--mit);
  display: inline-block; margin-bottom: 30px;
  box-shadow: 0 6px 18px -6px rgba(117,0,20,.5);
}
.hero h1 {
  font-family: var(--sans); font-weight: 800; letter-spacing: -.024em; line-height: 1.04;
  font-size: clamp(32px, 5.4vw, 56px); margin: 0 0 18px; max-width: 17ch;
}
.hero h1 .p { color: var(--accent); }
.hero .byline { margin: 0; font-size: 15px; font-weight: 700; color: var(--ink); letter-spacing: .01em; }

/* =============================================================================
 *  THE INSTRUMENT — one cohesive panel
 * ========================================================================== */
.instrument { margin-top: 8px; }
.panel {
  background: var(--paper);
  border: 1px solid var(--hair-2);
  border-radius: var(--r-lg);
  box-shadow: var(--shadow);
  overflow: hidden;
}

/* ---- setup -------------------------------------------------------------- */
.setup { padding: 28px 30px 26px; }
@media (max-width: 560px){ .setup { padding: 22px 18px; } }
.setup-head { margin-bottom: 20px; }
.eyebrow {
  font-family: var(--mono); font-size: 11px; letter-spacing: .18em; text-transform: uppercase;
  color: var(--mit); margin: 0 0 8px;
}
.setup-sub { margin: 0; font-size: 14px; color: var(--ink-3); max-width: 64ch; }
.setup-sub strong { color: var(--ink-2); font-weight: 700; }

.inputs { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
@media (max-width: 600px){ .inputs { grid-template-columns: 1fr; } }
.input-card {
  border: 1px solid var(--hair); border-radius: var(--r); padding: 15px 16px 16px;
  background: var(--paper-2); transition: border-color .15s, box-shadow .15s;
}
.input-card:focus-within { border-color: var(--mit); box-shadow: 0 0 0 3px rgba(117,0,20,.08); }
.ic-head { display: flex; align-items: center; gap: 11px; margin-bottom: 13px; }
.ic-num { font-family: var(--mono); font-size: 11px; color: var(--accent); letter-spacing: .04em; }
.ic-name {
  flex: 1; min-width: 0; border: none; background: transparent; padding: 3px 0 5px;
  border-bottom: 1.5px solid var(--hair-2); border-radius: 0;
  font-family: var(--sans); font-weight: 700; font-size: 16px; color: var(--ink);
  outline: none; transition: border-color .15s;
}
.ic-name:focus { border-bottom-color: var(--mit); }
.ic-range { display: grid; grid-template-columns: 1fr auto 1fr 72px; gap: 8px; align-items: center; }
.ic-range .dash { color: var(--ink-4); text-align: center; }
.ic-unit { color: var(--ink-3); }
.ic-rm {
  border: none; background: transparent; color: var(--ink-4); cursor: pointer;
  font-size: 17px; line-height: 1; padding: 2px 4px; border-radius: var(--r);
  transition: color .12s;
}
.ic-rm:hover { color: var(--accent); }
.add-input { margin-top: 12px; padding: 8px 14px; font-size: 12px; }

/* shared inputs */
input[type=text], input[type=number] {
  width: 100%; background: var(--paper); border: 1px solid var(--hair-2); color: var(--ink);
  border-radius: var(--r); padding: 9px 10px; font-size: 13px; font-family: var(--sans);
  outline: none; transition: border-color .14s, box-shadow .14s;
}
.num, input[type=number] { font-family: var(--mono); }
input:focus { border-color: var(--mit); box-shadow: 0 0 0 3px rgba(117,0,20,.10); }

.setup-foot { display: flex; align-items: center; gap: 10px; margin-top: 20px; flex-wrap: wrap; }

/* buttons */
.btn {
  font-family: var(--sans); font-weight: 600; font-size: 13px; border-radius: var(--r);
  border: 1px solid var(--hair-2); padding: 11px 20px; cursor: pointer;
  background: var(--paper); color: var(--ink); transition: background .12s, color .12s, border-color .12s, box-shadow .12s;
}
.btn:hover:not(:disabled) { background: var(--paper-2); border-color: var(--ink-3); }
.btn:disabled { opacity: .4; cursor: not-allowed; }
.btn.primary {
  background: var(--mit); border-color: var(--mit); color: #fff; padding: 11px 26px;
  box-shadow: 0 8px 20px -10px rgba(117,0,20,.7);
}
.btn.primary:hover:not(:disabled) { background: var(--mit-2); border-color: var(--mit-2); }

/* options disclosure */
details.adv { margin-left: auto; }
details.adv > summary {
  font-family: var(--mono); font-size: 11px; letter-spacing: .12em; text-transform: uppercase;
  color: var(--ink-3); cursor: pointer; list-style: none; padding: 9px 6px;
}
details.adv > summary:hover { color: var(--mit); }
details.adv > summary::-webkit-details-marker { display: none; }
details.adv > summary::before { content: "+ "; color: var(--accent); }
details.adv[open] > summary::before { content: "– "; }
.adv-body {
  display: grid; grid-template-columns: 1fr 1fr; gap: 13px 16px;
  margin-top: 14px; padding: 18px; border: 1px solid var(--hair); border-radius: var(--r);
  background: var(--paper-2); flex-basis: 100%;
}
.adv-body .span2 { grid-column: 1 / -1; }
label.fld { display: block; }
label.fld > span { display: block; font-size: 11px; color: var(--ink-3); margin-bottom: 5px; }
.rule-note {
  font-size: 11.5px; color: var(--ink-2); border-left: 2px solid var(--mit);
  padding: 8px 11px; line-height: 1.45; background: var(--paper); border-radius: 0 var(--r) var(--r) 0;
}

/* toggles */
.toggle { display: flex; align-items: center; justify-content: space-between; gap: 10px; }
.toggle .t-txt { font-size: 12.5px; font-weight: 600; }
.toggle .t-sub { font-size: 10.5px; color: var(--ink-4); margin-top: 1px; }
.sw { width: 38px; height: 21px; border-radius: 999px; background: var(--hair-2); position: relative; cursor: pointer; flex: none; transition: background .16s; }
.sw::after { content: ""; position: absolute; top: 2.5px; left: 2.5px; width: 16px; height: 16px; border-radius: 50%; background: #fff; box-shadow: 0 1px 2px rgba(0,0,0,.25); transition: left .16s; }
.sw.on { background: var(--mit); }
.sw.on::after { left: 19.5px; }

/* ---- stage / map -------------------------------------------------------- */
.stage { border-top: 1px solid var(--hair); }
.stage-top { display: grid; grid-template-columns: 1fr 58px; background: var(--paper-2); }
.canvas-host { position: relative; aspect-ratio: 1 / 1; overflow: hidden; cursor: crosshair; }
#heat, #overlay { position: absolute; inset: 0; width: 100%; height: 100%; display: block; }
#overlay { pointer-events: none; }
.tip {
  position: absolute; display: none; pointer-events: none; z-index: 4;
  font-family: var(--mono); font-size: 10.5px; line-height: 1.5; white-space: nowrap;
  background: rgba(255,255,255,.96); color: var(--ink); border: 1px solid var(--hair-2);
  border-left: 2px solid var(--mit); border-radius: 0 var(--r) var(--r) 0;
  padding: 6px 9px; box-shadow: 0 6px 18px -8px rgba(15,15,15,.35);
}
.tip .p { color: var(--mit); font-weight: 700; }
.empty-msg {
  position: absolute; inset: 0; display: flex; align-items: center; justify-content: center; text-align: center;
  color: var(--ink-4); font-size: 13px; padding: 36px; flex-direction: column; gap: 10px;
  background:
    radial-gradient(140% 100% at 50% 0%, var(--paper) 0%, var(--paper-2) 100%);
}
.empty-msg .em-dot { width: 14px; height: 14px; border-radius: 50%; background: var(--mit); opacity: .85; margin-bottom: 4px; }
.empty-msg .big { font-family: var(--sans); font-weight: 800; font-size: 17px; letter-spacing: -.01em; color: var(--ink-2); }
.empty-msg .em-sub { max-width: 38ch; line-height: 1.55; }
.empty-msg strong { color: var(--ink-2); font-weight: 700; }

.colorbar { border-left: 1px solid var(--hair); display: flex; flex-direction: column; align-items: center; padding: 16px 0; gap: 8px; background: var(--paper); }
.colorbar .scale { flex: 1; width: 13px; border-radius: 3px; border: 1px solid var(--hair-2); }
.colorbar .end { font-family: var(--mono); font-size: 9.5px; color: var(--ink-4); }
.colorbar .ttl { font-family: var(--mono); font-size: 9px; letter-spacing: .12em; color: var(--ink-3); writing-mode: vertical-rl; }

/* slice sliders (inputs 3+) */
.slice-row {
  display: flex; flex-direction: column; gap: 8px;
  border-top: 1px solid var(--hair); padding: 12px 18px; background: var(--paper);
}
.slice-item { display: flex; align-items: center; gap: 14px; }
.slice-lab { font-family: var(--mono); font-size: 11px; color: var(--ink-3); min-width: 220px; }
.slice-item input[type=range] { flex: 1; accent-color: var(--mit); width: auto; padding: 0; border: none; }

/* 3-D boundary cloud (exactly three inputs) */
.cloud-wrap { border-top: 1px solid var(--hair); background: var(--paper); }
.cloud-head { display: flex; align-items: baseline; justify-content: space-between; padding: 12px 18px 0; }
.cloud-ttl { font-family: var(--mono); font-size: 9.5px; letter-spacing: .14em; text-transform: uppercase; color: var(--ink-4); }
.cloud-hint { font-family: var(--mono); font-size: 9.5px; color: var(--ink-4); }
.cloud-leg { font-family: var(--mono); font-size: 9.5px; color: var(--ink-4); }
.cloud-leg i { display: inline-block; width: 8px; height: 8px; border-radius: 50%; vertical-align: -1px; margin-right: 4px; }
.cloud-leg b { font-weight: 700; vertical-align: -1px; }
.cloud-leg .up { color: #f9a009; }
.cloud-leg .dn { color: #57106e; }
.cloud-leg .bd { background: rgba(10,10,10,.9); }
.cloud-host { position: relative; height: 340px; }
#cloud { position: absolute; inset: 0; width: 100%; height: 100%; display: block; cursor: grab; }
#cloud:active { cursor: grabbing; }

/* probe banner */
.probe-banner {
  display: flex; align-items: center; gap: 16px; border-top: 1px solid var(--hair); padding: 14px 18px;
  background: var(--paper);
}
.probe-banner .pb-text { min-width: 0; }
.probe-banner .lbl { font-family: var(--mono); font-size: 9.5px; letter-spacing: .14em; text-transform: uppercase; color: var(--ink-4); }
.probe-banner .val { font-family: var(--mono); font-size: 16px; color: var(--mit); margin-top: 3px; }
.probe-banner.done .val { color: var(--ok); }
.probe-banner .answer { margin-left: auto; display: flex; gap: 10px; flex: none; }
.ans-btn {
  font-family: var(--sans); font-weight: 700; font-size: 13px; padding: 11px 18px; border-radius: var(--r);
  cursor: pointer; border: 1px solid; transition: filter .12s, transform .04s, background .12s; white-space: nowrap;
}
.ans-btn:active { transform: translateY(1px); }
.ans-btn:disabled { opacity: .35; cursor: not-allowed; }
.ans-btn.yes { background: var(--mit); border-color: var(--mit); color: #fff; box-shadow: 0 8px 18px -12px rgba(117,0,20,.8); }
.ans-btn.no { background: var(--paper); border-color: var(--ink-3); color: var(--ink-2); }
.ans-btn.yes:hover:not(:disabled) { filter: brightness(1.12); }
.ans-btn.no:hover:not(:disabled) { background: var(--paper-2); }
kbd { font-family: var(--mono); font-size: 9px; background: rgba(255,255,255,.18); border: 1px solid rgba(255,255,255,.35);
  border-radius: 3px; padding: 0 4px; margin-left: 7px; }
.ans-btn.no kbd { background: rgba(0,0,0,.05); border-color: var(--hair-2); color: var(--ink-3); }
@media (max-width: 540px){ .probe-banner { flex-direction: column; align-items: stretch; } .probe-banner .answer { margin-left: 0; } .ans-btn { flex: 1; } }

/* readout strip */
.readout { display: grid; grid-template-columns: 0.7fr 1.2fr 1.1fr 0.9fr; border-top: 1px solid var(--hair); }
@media (max-width: 540px){ .readout { grid-template-columns: 1fr 1fr; } }
.cell { padding: 13px 16px; border-right: 1px solid var(--hair); }
.cell:last-child { border-right: none; }
.cell .k { font-family: var(--mono); font-size: 9.5px; letter-spacing: .12em; text-transform: uppercase; color: var(--ink-4); }
.cell .v { font-family: var(--mono); font-size: 20px; margin-top: 5px; letter-spacing: -.01em; }
.cell .v small { font-size: 11px; color: var(--ink-4); }
.cell .v.ok { color: var(--ok); }
.cell:last-child .v { font-size: 15px; }
#bandSpark { display: block; width: 100%; height: 64px; margin-top: 7px; }
.meter { height: 4px; background: var(--paper-3); margin-top: 9px; position: relative; overflow: hidden; border-radius: 2px; }
.meter > i { display: block; height: 100%; background: linear-gradient(90deg, var(--mit), var(--mit-2)); width: 0%; transition: width .35s; }
.meter .thr { position: absolute; top: -2px; bottom: -2px; width: 1px; background: var(--accent); }

/* boundary kinematics line (width / drift speed with error bars) */
.kinline { font-family: var(--mono); font-size: 10.5px; color: var(--ink-3);
  border-top: 1px solid var(--hair); padding: 8px 16px; letter-spacing: .01em; }

/* folded-boundary warning over the 3-D view */
.fold-warn { font-size: 11.5px; color: var(--ink-2); background: var(--paper);
  border-left: 2px solid var(--accent); border-radius: 0 var(--r) var(--r) 0;
  padding: 7px 11px; margin: 8px 0 2px; line-height: 1.45; }

/* toolbar under readout */
.toolbar { display: flex; align-items: center; gap: 10px; border-top: 1px solid var(--hair); padding: 11px 16px; flex-wrap: wrap; background: var(--paper-2); }
.legend { display: flex; gap: 15px; align-items: center; font-family: var(--mono); font-size: 10.5px; color: var(--ink-3); flex-wrap: wrap; }
.legend i { display: inline-block; vertical-align: -1px; margin-right: 5px; }
.legend .yes { width: 9px; height: 9px; border-radius: 50%; background: var(--detect); }
.legend .no { width: 9px; height: 9px; border-radius: 50%; background: #fff; border: 1.5px solid var(--ink-3); }
.legend .pr { color: var(--accent); font-weight: 700; }
.legend .bd { width: 14px; height: 0; border-top: 1.6px dashed var(--ink); }
.toolbar .sp { flex: 1; }
.seg { display: inline-flex; border: 1px solid var(--hair-2); border-radius: var(--r); overflow: hidden; background: var(--paper); }
.seg button { border: none; background: transparent; color: var(--ink-3); padding: 6px 11px; font-size: 11px; font-family: var(--mono); cursor: pointer; transition: background .12s, color .12s; }
.seg button:hover:not(.on) { color: var(--ink); }
.seg button.on { background: var(--ink); color: #fff; }

/* toast */
#toast {
  position: fixed; left: 50%; bottom: 28px; transform: translateX(-50%) translateY(16px);
  background: var(--ink); color: #fff; padding: 11px 18px; border-radius: var(--r); font-size: 13px;
  opacity: 0; pointer-events: none; transition: opacity .2s, transform .2s; z-index: 60; max-width: 84vw;
  box-shadow: 0 16px 40px -16px rgba(0,0,0,.5);
}
#toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }
#toast.err { background: var(--accent); }

@media (prefers-reduced-motion: reduce) { * { animation: none !important; transition: none !important; } }