* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html,
body {
  height: 100%;
  overflow: hidden;
  background: #241539;
}

body {
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI",
    "Helvetica Neue", Arial, sans-serif;
}

#stage {
  position: fixed;
  inset: 0;
  overflow: hidden;
  background: var(--bg, #bd79d6);
  cursor: grab;
  touch-action: none;
}

#stage.dragging {
  cursor: grabbing;
}

/* Inset by a hairline so the outermost borders sit inside the screen edge
   instead of being sliced in half by it. The ring shows the stage colour. */
#clip {
  position: absolute;
  inset: 6px;
  overflow: hidden;
}

/* The whole nest pivots around the eye of the spiral: 72.36% / 72.36% */
#spiral {
  position: absolute;
  inset: 0;
  transform-origin: 72.36068% 72.36068%;
  will-change: transform;
}

/* A golden rectangle. Every level is the same element, 1/phi the size,
   rotated a further 90deg. */
.frame {
  position: absolute;
  aspect-ratio: 1.6180339887/1;
}

.frame.child {
  left: 100%;
  top: 0;
  width: 61.8033989%;
  transform-origin: 0 0;
  transform: rotate(90deg);
}

/* The square carved off each golden rectangle */
.panel {
  position: absolute;
  left: 0;
  top: 0;
  width: 61.8033989%;
  height: 100%;
  background: var(--panel, #3b2159);
  border: 1px solid var(--line, #bd79d6);
  overflow: hidden;
}

/* Plates are drawn, not loaded: no requests, and sharp from full-screen
   down to the last sub-pixel square. */
.art {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
}

.art .ink {
  fill: var(--ink, #c07be0);
}

.art .acc {
  fill: var(--accent, #f0b6ff);
}

.art .line {
  fill: none;
  stroke: var(--ink, #c07be0);
  stroke-linecap: round;
}

/* Sound toggle. It takes its colours from the section it sits on, so it
   recolours with the rest of the page as the sequence turns. Set --radius to
   reshape it: 50% a circle, 0 square, anything between rounded. */
#sound {
  position: absolute;
  bottom: 18px;
  left: 18px;
  z-index: 2;

  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;

  padding: 0;
  border: 1px solid var(--line, #bd79d6);
  border-radius: var(--radius, 50%);

  background: var(--panel, #3b2159);
  color: var(--bg, #bd79d6);

  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

#sound svg {
  width: 17px;
  height: 17px;
  display: block;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.6;
  stroke-linecap: round;
  stroke-linejoin: round;
}

/* The cone is solid; only the waves and the cross come and go. */
#sound .cone {
  fill: currentColor;
  stroke: none;
}