:root {
  color-scheme: dark;

  --surface:        #0e0e12;
  --panel:          #101014;
  --hairline:       rgba(255, 255, 255, 0.14);
  --text-primary:   #ffffff;
  --text-secondary: #c3c2b7;
  --text-muted:     #898781;

  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  height: 100%;
  overflow: hidden;
  background: var(--surface);
  color: var(--text-primary);
  font-family: var(--mono);
  font-size: 12px;
  -webkit-text-size-adjust: 100%;
}

#stage {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
  touch-action: none;
  cursor: grab;
}
#stage.dragging { cursor: grabbing; }

/* ---------------------------------------------------------------- panel */

#panel {
  position: fixed;
  bottom: 12px;
  left: 12px;
  width: 268px;
  max-height: calc(100% - 24px);
  display: flex;
  flex-direction: column;
  background: var(--panel);
  border: 1px solid var(--hairline);
  overflow: hidden;
}

#panel-head {
  padding: 8px 12px;
  border-bottom: 1px solid var(--hairline);
}

#panel h1 {
  margin: 0;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-secondary);
}

#panel-body {
  overflow-y: auto;
  overscroll-behavior: contain;
  padding-bottom: 6px;
}

#panel section {
  padding: 12px;
}

/* polynomial list */

#poly-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 5px;
}

#poly-list li {
  display: flex;
  align-items: center;
  gap: 6px;
}

.swatch {
  flex: none;
  width: 14px;
  height: 14px;
  border: 0;
  padding: 0;
  cursor: pointer;
  position: relative;
}
.swatch::after {
  content: "";
  position: absolute;
  inset: 0;
  border: 1px solid rgba(255, 255, 255, 0.25);
}
li.off .swatch { background: transparent !important; }
li.off .expr { color: var(--text-muted); text-decoration: line-through; }

.expr {
  flex: 1 1 auto;
  min-width: 0;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text-primary);
  background: transparent;
  border: 1px solid transparent;
  padding: 3px 5px;
}
.expr:hover { border-color: var(--hairline); }
.expr:focus {
  outline: none;
  border-color: rgba(255, 255, 255, 0.35);
  background: rgba(255, 255, 255, 0.05);
}
li.bad .expr { color: #e66767; }

.icon {
  flex: none;
  width: 20px;
  height: 20px;
  border: 0;
  background: transparent;
  color: var(--text-muted);
  font-size: 13px;
  line-height: 1;
  cursor: pointer;
}
.icon:hover { background: rgba(255, 255, 255, 0.08); color: var(--text-primary); }

.warn { flex: none; color: #c98500; font-size: 11px; cursor: help; }

#poly-add {
  display: flex;
  gap: 6px;
  margin-top: 8px;
}
#poly-input {
  flex: 1 1 auto;
  min-width: 0;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--hairline);
  padding: 5px 7px;
}
#poly-input:focus { outline: none; border-color: rgba(255, 255, 255, 0.35); }
#poly-input::placeholder { color: var(--text-muted); }

#err-pop {
  margin-top: 8px;
  padding: 5px 8px;
  border: 1px solid rgba(230, 103, 103, 0.35);
  background: rgba(230, 103, 103, 0.10);
  color: #e66767;
  font-family: var(--mono);
  font-size: 11px;
  line-height: 1.4;
}
#err-pop[hidden] { display: none; }

/* controls */

button {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid var(--hairline);
  padding: 3px 6px;
  cursor: pointer;
}
button:hover { background: rgba(255, 255, 255, 0.12); }

/* ------------------------------------------------------------- overlays */

#tooltip {
  position: fixed;
  z-index: 5;
  pointer-events: none;
  transform: translate(12px, 12px);
  padding: 5px 8px;
  border: 1px solid var(--hairline);
  background: rgba(14, 14, 18, 0.92);
  font-family: var(--mono);
  font-size: 11px;
  line-height: 1.5;
  white-space: nowrap;
  color: var(--text-secondary);
  font-variant-numeric: tabular-nums;
}
#tooltip .n { color: var(--text-primary); font-weight: 600; }
#tooltip .p { color: #3987e5; }

#loading {
  position: fixed;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--surface);
  color: var(--text-muted);
  font-size: 12px;
  letter-spacing: 0.04em;
  z-index: 10;
  transition: opacity 0.25s ease;
}
#loading.done { opacity: 0; pointer-events: none; }

@media (max-width: 560px) {
  #panel { width: calc(100% - 24px); max-height: calc(100% - 24px); }
}