/* =====================================================================
   Shape Transformations — tool styles
   ---------------------------------------------------------------------
   One screenful, three panels:
     Transform (left)        the four transformations, stacked; kept
                             narrow so the plane gets the room
     Coordinate plane        shape picker, quadrant zoom and status in
                             a column beside the plane, so the plane can
                             use the panel's full height
     Measurements (right)    coordinates, lengths and area; scrolls on
                             its own so the graph never moves. It can pop
                             out as a x2 window you drag anywhere, and the
                             plane then grows into the space it leaves.

   On screens that are closer to square than 4:3 (portrait tablets,
   5:4 monitors) the measurements move UNDER the graph, where there is
   room for them. Phones stack everything and the page scrolls.

   Colors: every value points at a site.css token. Shape colors are the
   --data-* tokens, passed to each SVG element as --c by the script, so
   light and dark mode need no JavaScript.
   ===================================================================== */

:root {
  /* This tool's type steps, scaled down on short laptop screens so the
     one-screen layout always fits. Prefixed --st- to avoid clashes. */
  --ui-scale: 1;
  --st-fs-3xs: calc(.68rem * var(--ui-scale));
  --st-fs-2xs: calc(.74rem * var(--ui-scale));
  --st-fs-xs:  calc(.79rem * var(--ui-scale));
  --st-fs-sm:  calc(.84rem * var(--ui-scale));
  --st-fs-md:  calc(.95rem * var(--ui-scale));
  --st-fs-lg:  calc(1.05rem * var(--ui-scale));
  --st-fs-xl:  calc(1.21rem * var(--ui-scale));

  /* Plane sizes — SVG user units, which the script maps 1:1 to css
     pixels and rewrites from the root font size. These are fallbacks. */
  --fs-num: 15px;
  --fs-name: 19px;
  --fs-label: 20px;
  --fs-small: 15px;
  --sw-grid: 1.3px;
  --sw-grid-five: 2px;
  --sw-axis: 3.4px;
  --sw-side: 4px;
  --sw-aux: 3px;
  --sw-halo: 3px;

  /* graph paper: 2.5:1 minor lines, 4.8:1 every fifth, axes at full ink */
  --grid: #94a7c0;
  --grid-five: #64748b;
  --axis: var(--color-ink);
  --aux: var(--color-ink-soft);         /* helper lines: dashed, neutral ink */
  --plane-halo: var(--color-surface);   /* outline behind plane labels */

  --header-h: calc(3.6rem * var(--ui-scale));
  --gap: 12px;
  --pad: 12px;
  --body-pad: 12px 14px;
}

html[data-theme="dark"] {
  --grid: #34435f;
  --grid-five: #5f7190;
}

@media (max-height: 900px) {
  :root { --ui-scale: .95; --gap: 9px; --pad: 9px; --body-pad: 10px 12px; }
}

@media (max-height: 820px) {
  :root { --ui-scale: .88; --gap: 8px; --pad: 8px; --body-pad: 9px 11px; }
}

@media (max-height: 720px) {
  :root { --ui-scale: .8; --gap: 7px; --pad: 7px; --body-pad: 8px 10px; }
}

.tool-frame {
  display: flex;
  flex-direction: column;
  font-size: var(--st-fs-sm);
  color: var(--color-ink);
}

.tool-frame h1,
.tool-frame h2,
.tool-frame h3,
.tool-frame p {
  margin: 0;
}

/* ---------------- Title bar ---------------- */

.app-header {
  height: var(--header-h);
  flex: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 0 18px;
  background: var(--color-surface);
  border-bottom: var(--border-width) solid var(--color-border-strong);
  box-shadow: var(--shadow-sm);
  position: relative;
  z-index: 5;
}

.brand-tool {
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 0;
}

.brand-logo {
  display: grid;
  place-items: center;
  flex: none;
  width: calc(44px * var(--ui-scale));
  height: calc(44px * var(--ui-scale));
  border-radius: 11px;
  background: var(--color-accent-strong);
  color: var(--color-on-accent);
}

html[data-theme="dark"] .brand-logo {
  background: var(--color-accent);
}

.brand-logo svg {
  width: 62%;
  height: 62%;
}

.brand-text h1 {
  font-size: var(--st-fs-xl);
  font-weight: var(--fw-bold);
  letter-spacing: -.01em;
}

.brand-text p {
  margin-top: 2px;
  font-size: var(--st-fs-2xs);
  font-weight: var(--fw-bold);
  color: var(--color-ink-muted);
}

.header-actions {
  display: flex;
  gap: 10px;
  flex: none;
}

/* ---------------- Layout ---------------- */

.layout {
  flex: 1 1 auto;
  min-height: 0;
  display: grid;
  grid-template-columns: minmax(5.25rem, 6.5rem) minmax(0, 1.75fr) minmax(15rem, 1fr);
  grid-template-rows: minmax(0, 1fr);
  gap: var(--gap);
  padding: var(--pad);
}

/* Closer to square than 4:3: the read-out goes under the graph. */
@media (max-aspect-ratio: 4/3) and (min-width: 761px) {
  .layout {
    grid-template-columns: minmax(5.25rem, 6.5rem) minmax(0, 1fr);
    grid-template-rows: minmax(0, 1.75fr) minmax(0, 1fr);
  }

  .panel-moves {
    grid-row: 1 / span 2;
  }

  .panel-info {
    grid-column: 2;
  }
}

/* Measurements popped out: the plane takes every column that's left. */
.layout.info-out {
  grid-template-columns: minmax(5.25rem, 6.5rem) minmax(0, 1fr);
  grid-template-rows: minmax(0, 1fr);
}

.layout.info-out .panel-moves {
  grid-row: 1;
}

/* ...and moves to the left of its space, leaving the right side for the window. */
.layout.info-out .graph-body {
  justify-items: start;
}

.panel {
  display: flex;
  flex-direction: column;
  min-width: 0;
  min-height: 0;
  overflow: hidden;
  background: var(--color-surface);
  border: var(--border-width) solid var(--color-border-strong);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}

.panel-head {
  flex: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: calc(9px * var(--ui-scale)) 14px;
  background: var(--color-surface-2);
  border-bottom: var(--border-width) solid var(--color-border);
}

.panel-head h2 {
  font-size: var(--st-fs-xs);
  font-weight: var(--fw-bold);
  letter-spacing: .06em;
  text-transform: uppercase;
}

.panel-hint {
  font-size: var(--st-fs-2xs);
  font-weight: var(--fw-bold);
  color: var(--color-ink-muted);
  text-align: right;
}

.panel-body {
  flex: 1;
  min-height: 0;
  padding: var(--body-pad);
  overflow: auto;
}

/* ---------------- Transform buttons ---------------- */

.moves-body {
  display: flex;
  flex-direction: column;
  gap: calc(12px * var(--ui-scale));
}

.moves-list {
  display: flex;
  flex-direction: column;
  gap: calc(10px * var(--ui-scale));
}

.move-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  width: 100%;
  min-height: var(--tap-target);
  padding: calc(8px * var(--ui-scale)) 4px;
  font: inherit;
  text-align: center;
  color: var(--color-ink);
  background: var(--color-surface);
  border: var(--border-width) solid var(--color-border-strong);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: background-color var(--dur-fast), border-color var(--dur-fast), transform 80ms;
}

.move-btn:hover:not(:disabled) {
  background: var(--color-accent-soft);
  border-color: var(--color-accent);
}

.move-btn:active:not(:disabled) {
  transform: translateY(1px);
}

.move-btn:disabled {
  opacity: .5;
  cursor: not-allowed;
}

.move-icon {
  display: grid;
  place-items: center;
  flex: none;
  width: calc(2.3rem * var(--ui-scale));
  height: calc(2.3rem * var(--ui-scale));
  color: var(--color-on-accent);
  background: var(--color-accent);
  border-radius: var(--radius-sm);
}

.move-icon svg {
  width: 72%;
  height: 72%;
}

.move-text {
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.move-name {
  font-size: var(--st-fs-xs);
  font-weight: var(--fw-bold);
}

.move-sub {
  display: none;
  font-size: var(--st-fs-2xs);
  font-weight: var(--fw-bold);
  color: var(--color-ink-muted);
}

.moves-body {
  padding: calc(8px * var(--ui-scale)) 7px;
}

.panel-moves .panel-head {
  justify-content: center;
  padding-inline: 6px;
}

.moves-note {
  overflow-wrap: anywhere;
  font-size: var(--st-fs-3xs);
  line-height: 1.45;
  color: var(--color-ink-soft);
}

.moves-note b {
  color: var(--color-ink);
}

.undo-btn {
  margin-top: auto;
  white-space: normal;
}

/* ---------------- Graph panel head: shape picker + zoom ---------------- */

/* The plane panel is a grid: controls beside the plane on wide screens,
   above it (with the status underneath) on narrow ones. */
.panel-graph {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  grid-template-rows: minmax(0, 1fr) auto;
}

.graph-side {
  grid-column: 1;
  grid-row: 1;
  display: flex;
  flex-direction: column;
  gap: calc(12px * var(--ui-scale));
  width: calc(9.6rem * var(--ui-scale));
  min-height: 0;
  padding: 10px;
  overflow: auto;
  background: var(--color-surface-2);
  border-right: var(--border-width) solid var(--color-border);
}

.graph-side .picker-row {
  flex-direction: column;
  align-items: stretch;
}

.graph-side .shape-picker {
  flex-direction: column;
  border-radius: var(--radius-md);
}

.graph-side .seg span {
  width: 100%;
  border-radius: var(--radius-sm);
}

.graph-side .sides-box {
  justify-content: center;
}

.graph-side .zoom-picker {
  flex-direction: column;
  align-items: stretch;
  margin: 0;
}

.graph-side .zoom-all {
  height: calc(1.9rem * var(--ui-scale));
}

.graph-side .zoom-quads button {
  height: calc(1.7rem * var(--ui-scale));
}

.panel-graph .graph-body {
  grid-column: 2;
  grid-row: 1 / span 2;
}

.panel-graph .graph-status {
  grid-column: 1;
  grid-row: 2;
  width: calc(9.6rem * var(--ui-scale));
  text-align: left;
  background: var(--color-surface-2);
  border-right: var(--border-width) solid var(--color-border);
}

/* Narrow or portrait: controls go back on top, status underneath. */
@media (max-aspect-ratio: 4/3), (max-width: 760px) {
  .panel-graph {
    grid-template-columns: minmax(0, 1fr);
    grid-template-rows: auto minmax(0, 1fr) auto;
  }

  .graph-side {
    flex-direction: row;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    width: auto;
    padding: calc(7px * var(--ui-scale)) 14px;
    border-right: 0;
    border-bottom: var(--border-width) solid var(--color-border);
  }

  .graph-side .picker-row {
    flex-direction: row;
    align-items: center;
  }

  .graph-side .shape-picker {
    flex-direction: row;
    border-radius: var(--radius-pill);
  }

  .graph-side .seg span {
    width: auto;
    border-radius: var(--radius-pill);
  }

  .graph-side .zoom-picker {
    flex-direction: row;
    align-items: center;
  }

  .graph-side .zoom-all {
    height: calc(2.1rem * var(--ui-scale) + 2px);
  }

  .graph-side .zoom-quads button {
    height: calc(1.15rem * var(--ui-scale));
  }

  .panel-graph .graph-body {
    grid-column: 1;
    grid-row: 2;
  }

  .panel-graph .graph-status {
    grid-column: 1;
    grid-row: 3;
    width: auto;
    text-align: center;
    border-right: 0;
  }
}

.picker-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 10px;
  min-width: 0;
}

.shape-picker {
  display: flex;
  flex-wrap: wrap;
  margin: 0;
  padding: 3px;
  border: var(--border-width) solid var(--color-border-strong);
  border-radius: var(--radius-pill);
  background: var(--color-surface);
}

.seg {
  position: relative;
}

.seg input {
  position: absolute;
  opacity: 0;
  inset: 0;
  margin: 0;
  cursor: pointer;
}

.seg span {
  display: inline-flex;
  align-items: center;
  gap: .4em;
  min-height: calc(2.1rem * var(--ui-scale));
  padding: 0 .85em;
  font-size: var(--st-fs-sm);
  font-weight: var(--fw-bold);
  color: var(--color-ink-soft);
  border-radius: var(--radius-pill);
  transition: background-color var(--dur-fast), color var(--dur-fast);
}

.seg svg {
  width: 1.05em;
  height: 1.05em;
  fill: none;
  stroke: currentColor;
  stroke-width: 2.6;
  stroke-linejoin: round;
}

.seg input:hover + span {
  background: var(--color-surface-2);
  color: var(--color-ink);
}

.seg input:checked + span {
  background: var(--color-accent);
  color: var(--color-on-accent);
}

.seg input:focus-visible + span {
  outline: var(--focus-width) solid var(--color-focus);
  outline-offset: 2px;
}

.sides-box {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: var(--st-fs-sm);
  font-weight: var(--fw-bold);
  color: var(--color-ink-soft);
}

.sides-out b {
  display: inline-block;
  min-width: 1.4em;
  text-align: center;
  font-size: var(--st-fs-lg);
  color: var(--color-ink);
}

.step-btn {
  display: grid;
  place-items: center;
  width: calc(2.1rem * var(--ui-scale));
  height: calc(2.1rem * var(--ui-scale));
  padding: 0;
  font: inherit;
  font-size: var(--st-fs-lg);
  font-weight: var(--fw-bold);
  line-height: 1;
  color: var(--color-ink);
  background: var(--color-surface);
  border: var(--border-width) solid var(--color-border-strong);
  border-radius: var(--radius-sm);
  cursor: pointer;
}

.step-btn:hover:not(:disabled) {
  background: var(--color-accent-soft);
  border-color: var(--color-accent);
}

.step-btn:disabled {
  opacity: .4;
  cursor: not-allowed;
}

/* Zoom: "All" plus a 2 × 2 block laid out like the quadrants */
.zoom-picker {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-left: auto;
}

.zoom-quads {
  display: grid;
  grid-template-columns: repeat(2, auto);
  gap: 2px;
}

.zoom-picker button {
  min-width: calc(1.9rem * var(--ui-scale));
  padding: 0 .35em;
  font: inherit;
  font-size: var(--st-fs-2xs);
  font-weight: var(--fw-bold);
  line-height: 1;
  color: var(--color-ink-soft);
  background: var(--color-surface);
  border: var(--border-width) solid var(--color-border-strong);
  cursor: pointer;
}

.zoom-quads button {
  height: calc(1.15rem * var(--ui-scale));
  border-radius: 5px;
}

.zoom-all {
  height: calc(2.1rem * var(--ui-scale) + 2px);
  border-radius: var(--radius-sm);
}

.zoom-picker button:hover {
  background: var(--color-accent-soft);
  border-color: var(--color-accent);
  color: var(--color-accent-strong);
}

.zoom-picker button[aria-pressed="true"] {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-on-accent);
}

/* ---------------- The plane ---------------- */

.graph-body {
  display: grid;
  place-items: center;
  padding: 6px;
  overflow: visible;
}

/* Largest square that fits (same technique as the Graphing Explorer). */
.graph-stage {
  position: relative;
  height: 100%;
  aspect-ratio: 1 / 1;
  max-width: 100%;
  max-height: 100%;
}

@supports (width: 1cqmin) {
  .graph-body {
    container-type: size;
  }

  .graph-stage {
    width: 100cqmin;
    height: 100cqmin;
  }
}

#plane {
  display: block;
  width: 100%;
  height: 100%;
  touch-action: none;
  user-select: none;
  -webkit-user-select: none;
  cursor: default;
}

/* Cursors say what a drag will do */
#plane.cur-add    { cursor: crosshair; }
#plane.cur-grab   { cursor: grab; }
#plane.cur-move   { cursor: move; }
#plane.cur-resize { cursor: nwse-resize; }
#plane.cur-pick   { cursor: pointer; }
#plane.cur-rotate {
  cursor: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='28' height='28' viewBox='0 0 28 28'%3E%3Cg fill='none' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M22 14a8 8 0 1 1-2.4-5.7' stroke='%23fff' stroke-width='6'/%3E%3Cpath d='M21 3.5v5.2h-5.2' stroke='%23fff' stroke-width='6'/%3E%3Cpath d='M22 14a8 8 0 1 1-2.4-5.7' stroke='%230b1220' stroke-width='2.6'/%3E%3Cpath d='M21 3.5v5.2h-5.2' stroke='%230b1220' stroke-width='2.6'/%3E%3C/g%3E%3C/svg%3E") 14 14, grab;
}
#plane.is-dragging { cursor: grabbing; }

.plot-bg     { fill: var(--color-surface); }
.plot-frame  { fill: none; stroke: var(--color-border-strong); stroke-width: var(--sw-grid-five); }
.grid-line   { stroke: var(--grid); stroke-width: var(--sw-grid); }
.grid-line.five { stroke: var(--grid-five); stroke-width: var(--sw-grid-five); }
.axis        { stroke: var(--axis); stroke-width: var(--sw-axis); stroke-linecap: square; }

.axis-num,
.axis-name {
  font-family: var(--font-sans);
  font-weight: var(--fw-bold);
  fill: var(--color-ink);
  paint-order: stroke;
  stroke: var(--plane-halo);
  stroke-linejoin: round;
  dominant-baseline: central;
}

.axis-num  { font-size: var(--fs-num);  stroke-width: calc(var(--fs-num) * .3); }
.axis-name { font-size: var(--fs-name); stroke-width: calc(var(--fs-name) * .3); font-style: italic; }

/* Shapes. --c is set per element by the script. */
.shape-fill {
  fill: var(--c);
  fill-opacity: .2;
  stroke: none;
  transition: fill-opacity var(--dur-fast);
}

.shape-fill.is-hl {
  fill-opacity: .36;
}

.side {
  fill: none;
  stroke: var(--c);
  stroke-width: var(--sw-side);
  stroke-linecap: round;
  stroke-linejoin: round;
}

.shape-fill.is-selected {
  fill-opacity: .42;
}

.side.is-selected {
  stroke-dasharray: calc(var(--sw-side) * 2.5) calc(var(--sw-side) * 1.2);
}

.side.is-hl {
  stroke-width: calc(var(--sw-side) * 2.1);
}

.side-glow {
  fill: none;
  stroke: var(--plane-halo);
  stroke-width: calc(var(--sw-side) * 3.4);
  stroke-linecap: round;
  opacity: 0;
}

.side-glow.is-hl {
  opacity: 1;
}

/* Helper lines (heights, diagonals, radius): dashed and neutral, so they
   never read as a side. The same dashed key appears in the Lengths list. */
.aux {
  fill: none;
  stroke: var(--aux);
  stroke-width: var(--sw-aux);
  stroke-dasharray: calc(var(--sw-aux) * 3) calc(var(--sw-aux) * 2.2);
  stroke-linecap: butt;
}

/* A halo under each helper line keeps its dashes readable where it runs along an axis or grid line. */
.aux-halo {
  fill: none;
  stroke: var(--plane-halo);
  stroke-width: calc(var(--sw-aux) * 2.2);
  opacity: .85;
}

.aux.is-ext {
  stroke-dasharray: calc(var(--sw-aux) * .9) calc(var(--sw-aux) * 2.2);
  stroke-linecap: round;
  opacity: .8;
}

.aux.is-hl {
  stroke: var(--c);
  stroke-width: calc(var(--sw-aux) * 1.8);
}

.right-mark {
  fill: none;
  stroke: var(--aux);
  stroke-width: calc(var(--sw-aux) * .8);
}

.aux-label {
  font: italic var(--fw-bold) var(--fs-label) var(--font-sans);
  fill: var(--aux);
  paint-order: stroke;
  stroke: var(--plane-halo);
  stroke-width: calc(var(--fs-label) * .3);
  stroke-linejoin: round;
  text-anchor: middle;
  dominant-baseline: central;
  pointer-events: none;
}

/* Points */
.pt-dot {
  fill: var(--c);
  stroke: var(--plane-halo);
  stroke-width: var(--sw-halo);
}

.pt-ring {
  fill: none;
  stroke: var(--c);
  stroke-width: var(--sw-halo);
  opacity: 0;
  transition: opacity var(--dur-fast);
}

.pt-ring.is-hl {
  opacity: 1;
}

.pt-label {
  font: var(--fw-bold) var(--fs-label) var(--font-sans);
  fill: var(--c);
  paint-order: stroke;
  stroke: var(--plane-halo);
  stroke-width: calc(var(--fs-label) * .3);
  stroke-linejoin: round;
  text-anchor: middle;
  dominant-baseline: central;
  pointer-events: none;
}

.pt-label.is-hl {
  text-decoration: underline;
}

/* A new image fades in */
.is-new {
  animation: shapeIn .5s var(--ease-out);
}

@keyframes shapeIn {
  from { opacity: 0; }
}

/* Transformation guides: arrows, the mirror line, center of rotation,
   rays of a dilation. Drawn for a hovered point and its pair, and for
   the whole shape in a pop-up's preview. */
.guide-line {
  fill: none;
  stroke: var(--c);
  stroke-width: calc(var(--sw-aux) * .8);
  stroke-dasharray: 1 calc(var(--sw-aux) * 2.4);
  stroke-linecap: round;
  opacity: .9;
}

.guide-mirror {
  fill: none;
  stroke: var(--c);
  stroke-width: var(--sw-side);
  stroke-dasharray: calc(var(--sw-side) * 3) calc(var(--sw-side) * 2);
  opacity: .75;
}

.guide-arrow {
  fill: none;
  stroke: var(--c);
  stroke-width: calc(var(--sw-aux) * .9);
  stroke-linecap: round;
  stroke-linejoin: round;
  opacity: .85;
}

/* Hovering a point joins it to its pair in the neighbouring shapes. */
.pair-line {
  fill: none;
  stroke: var(--c);
  stroke-width: var(--sw-aux);
  stroke-dasharray: calc(var(--sw-aux) * 2.4) calc(var(--sw-aux) * 1.6);
  stroke-linecap: round;
  pointer-events: none;
}

.pair-layer .guide-head {
  opacity: 1;
}

.guide-head {
  fill: var(--c);
  opacity: .85;
}

.guide-label {
  font: var(--fw-bold) var(--fs-small) var(--font-sans);
  fill: var(--c);
  paint-order: stroke;
  stroke: var(--plane-halo);
  stroke-width: calc(var(--fs-small) * .32);
  stroke-linejoin: round;
  dominant-baseline: central;
  pointer-events: none;
}

.center-ring {
  fill: var(--plane-halo);
  stroke: var(--color-ink);
  stroke-width: calc(var(--sw-aux) * .9);
}

.center-dot {
  fill: var(--color-ink);
}

/* Previews: the image a pop-up is about to create, and the free rotation
   while a side is being dragged. */
.ghost {
  fill: var(--c);
  fill-opacity: .08;
  stroke: var(--c);
  stroke-width: calc(var(--sw-side) * .8);
  stroke-dasharray: calc(var(--sw-side) * 2) calc(var(--sw-side) * 1.6);
  stroke-linejoin: round;
}

.ghost-label {
  opacity: .8;
}

/* Hover / drag read-out next to the pointer */
.graph-tip {
  position: absolute;
  z-index: 2;
  max-width: 22em;
  padding: 6px 11px;
  font-size: var(--st-fs-xs);
  font-weight: var(--fw-bold);
  line-height: 1.35;
  color: var(--color-ink-inverse);
  background: var(--color-ink);
  border: var(--border-width) solid var(--color-surface);
  border-radius: 9px;
  box-shadow: var(--shadow-md);
  pointer-events: none;
  white-space: nowrap;
  transform: translate(16px, -120%);
}

.graph-tip.flip {
  transform: translate(calc(-100% - 16px), -120%);
}

.graph-tip .tip-math {
  font-family: var(--font-mono);
}

/* Delete button that appears over a clicked shape */
.shape-action {
  position: absolute;
  z-index: 3;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 7px 14px;
  font: inherit;
  font-size: var(--st-fs-sm);
  font-weight: var(--fw-bold);
  line-height: 1.25;
  color: #ffffff;
  background: var(--color-danger);
  border: var(--border-width) solid var(--color-surface);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-md);
  cursor: pointer;
  white-space: nowrap;
  transform: translate(-50%, calc(-100% - 14px));
}

html[data-theme="dark"] .shape-action {
  color: var(--color-ink-inverse);
}

.shape-action small {
  font-size: var(--st-fs-3xs);
  font-weight: var(--fw-bold);
  opacity: .92;
}

.shape-action:hover {
  filter: brightness(.9);
}

.shape-action::after {
  content: "";
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  border: 8px solid transparent;
  border-top-color: var(--color-danger);
}

.graph-status {
  flex: none;
  padding: calc(7px * var(--ui-scale)) 14px;
  font-size: var(--st-fs-xs);
  font-weight: var(--fw-bold);
  line-height: 1.4;
  color: var(--color-ink-soft);
  text-align: center;
  background: var(--color-surface-2);
  border-top: var(--border-width) solid var(--color-border);
}

.graph-status b {
  color: var(--color-ink);
}

.graph-status.is-warn {
  color: var(--color-danger);
}

/* ---------------- Measurements ---------------- */

.head-right {
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
}

.zoom-btn {
  flex: none;
  display: grid;
  place-items: center;
  width: calc(32px * var(--ui-scale));
  height: calc(32px * var(--ui-scale));
  padding: 0;
  color: var(--color-ink-soft);
  background: var(--color-surface);
  border: var(--border-width) solid var(--color-border-strong);
  border-radius: 8px;
  cursor: pointer;
}

.zoom-btn svg {
  width: 62%;
  height: 62%;
}

.zoom-btn:hover {
  color: var(--color-accent-strong);
  background: var(--color-accent-soft);
  border-color: var(--color-accent);
}

.zoom-btn .icon-out,
.zoom-btn[aria-pressed="true"] .icon-in {
  display: none;
}

.zoom-btn[aria-pressed="true"] .icon-out {
  display: block;
}

.zoom-btn[aria-pressed="true"] {
  color: var(--color-on-accent);
  background: var(--color-accent);
  border-color: var(--color-accent);
}

/* Popped out: a floating window drawn at twice its size, still fully
   interactive (hover, scroll). Drag it by its heading. */
.panel-info.is-floating {
  position: fixed;
  z-index: 50;
  transform: scale(2);
  transform-origin: top left;
  border-color: var(--color-ink);
  box-shadow: var(--shadow-lg);
}

.panel-info.is-floating .panel-head {
  cursor: move;
  touch-action: none;
}

.panel-info.is-floating .panel-hint {
  display: none;
}

.panel-info.is-dragging {
  user-select: none;
}

.info-body {
  display: flex;
  flex-direction: column;
  gap: calc(14px * var(--ui-scale));
  overscroll-behavior: contain;
}

.field-title {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 4px 10px;
  margin-bottom: 6px !important;
  padding-bottom: 4px;
  font-size: var(--st-fs-xs);
  font-weight: var(--fw-bold);
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--color-ink);
  border-bottom: var(--border-width) solid var(--color-border-soft);
}

.field-key {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: var(--st-fs-3xs);
  letter-spacing: .02em;
  text-transform: none;
  color: var(--color-ink-muted);
}

.key-solid,
.key-dashed {
  display: inline-block;
  width: 1.6em;
  border-top: 3px solid var(--color-ink-soft);
}

.key-dashed {
  margin-left: 6px;
  border-top-style: dashed;
}

.field-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.field-empty {
  font-size: var(--st-fs-xs);
  line-height: 1.5;
  color: var(--color-ink-muted);
}

/* One group per shape, banded with the shape's color */
.group {
  padding: 6px 10px 8px;
  border: var(--border-width) solid var(--color-border-soft);
  border-left: var(--border-width-accent) solid var(--c);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
}

.group-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 2px 8px;
  padding: 2px 4px;
  border-radius: 6px;
}

.group-name {
  font-size: var(--st-fs-sm);
  font-weight: var(--fw-bold);
  color: var(--c);
}

.group-tag {
  font-size: var(--st-fs-3xs);
  font-weight: var(--fw-bold);
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}

.group-desc {
  margin: 2px 4px 4px !important;
  font-size: var(--st-fs-2xs);
  line-height: 1.4;
  color: var(--color-ink-soft);
}

.rule {
  display: inline-block;
  font-family: var(--font-mono);
  font-weight: var(--fw-bold);
  color: var(--color-ink);
  white-space: nowrap;
}

.group-note {
  margin: 4px 4px 0 !important;
  font-size: var(--st-fs-2xs);
  line-height: 1.4;
  color: var(--color-ink-muted);
}

.coord-list,
.len-list {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 6px;
  margin: 4px 0 0;
  padding: 0;
  list-style: none;
}

.len-list {
  flex-direction: column;
}

.coord,
.len {
  padding: 2px 8px;
  font-family: var(--font-mono);
  font-size: var(--st-fs-sm);
  font-weight: var(--fw-bold);
  line-height: 1.45;
  border: var(--border-width) solid transparent;
  border-radius: 6px;
  transition: background-color var(--dur-fast), border-color var(--dur-fast);
}

.coord b {
  color: var(--c);
}

.len {
  display: flex;
  align-items: baseline;
  gap: 8px;
}

.len-swatch {
  flex: none;
  width: 1.5em;
  border-top: 4px solid var(--c);
  transform: translateY(-.25em);
}

.len.is-aux .len-swatch {
  border-top: 3px dashed var(--aux);
}

.len.is-derived .len-swatch {
  border-top-color: transparent;
}

.len-text {
  min-width: 0;
  overflow-wrap: anywhere;
}

.len-tag {
  flex: none;
  margin-left: auto;
  font-family: var(--font-sans);
  font-size: var(--st-fs-3xs);
  font-weight: var(--fw-bold);
  color: var(--color-ink-muted);
}

.len.is-aux .len-tag {
  padding: 0 6px;
  border: 1px dashed var(--color-border-strong);
  border-radius: var(--radius-pill);
}

/* Highlight shared by the graph hover and the list hover */
.coord.is-hl,
.len.is-hl,
.group-head.is-hl {
  background: var(--color-surface-2);
  background: color-mix(in srgb, var(--c) 16%, var(--color-surface));
  border-color: var(--c);
}

.coord[data-key],
.len[data-key],
.group-head[data-key] {
  cursor: default;
}

.area-eq {
  margin: 4px 4px 0;
  font-family: var(--font-mono);
  font-size: var(--st-fs-sm);
  font-weight: var(--fw-bold);
  line-height: 1.55;
}

.eq-line {
  padding-left: 1.2em;
  text-indent: -1.2em;
}

.eq-formula {
  color: var(--color-ink);
}

.eq-method {
  margin-bottom: 2px;
  font-family: var(--font-sans);
  font-size: var(--st-fs-2xs);
  color: var(--color-ink-muted);
}

.eq-result {
  color: var(--c);
  font-size: var(--st-fs-md);
}

.warn-note {
  color: var(--color-danger);
}

/* ---------------- Modal ---------------- */

.modal-root {
  position: fixed;
  inset: 0;
  z-index: 100;
  display: none;
}

.modal-root.open {
  display: block;
}

.modal-backdrop {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  padding: 20px;
  overflow: auto;
  background: var(--color-overlay);
  backdrop-filter: blur(2px);
  animation: fade .15s ease-out;
}

/* Transformation forms sit beside the buttons and barely dim the plane,
   so the live preview stays readable behind them. */
.modal-backdrop.is-side {
  justify-items: start;
  padding-left: calc(var(--pad) + 1rem);
  background: rgba(11, 18, 32, .12);
  backdrop-filter: none;
}

html[data-theme="dark"] .modal-backdrop.is-side {
  background: rgba(2, 5, 12, .3);
}

@keyframes fade {
  from { opacity: 0; }
}

.modal {
  width: min(calc(540px * var(--ui-scale)), 100%);
  padding: calc(22px * var(--ui-scale));
  background: var(--color-surface);
  border: var(--border-width) solid var(--color-ink);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  animation: rise .18s cubic-bezier(.2, .9, .3, 1.2);
}

/* A pop-up never runs off a short screen: it scrolls instead. */
.modal {
  max-height: calc(100dvh - 24px);
  overflow-y: auto;
}

.modal-body {
  overflow-wrap: anywhere;
}

.is-side .modal {
  width: min(calc(460px * var(--ui-scale)), 100%);
}

@keyframes rise {
  from { opacity: 0; transform: translateY(10px) scale(.97); }
}

.modal-title {
  margin-bottom: 8px !important;
  font-size: var(--st-fs-xl);
  font-weight: var(--fw-bold);
}

.modal-body {
  font-size: var(--st-fs-md);
  line-height: 1.55;
  color: var(--color-ink-soft);
}

.modal-body p + p {
  margin-top: 8px;
}

.modal-lead b {
  color: var(--c, var(--color-ink));
}

.modal-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 9px;
  margin-top: 18px;
}

.form-block {
  margin: 14px 0 0;
  padding: 0;
  border: 0;
  min-width: 0;
}

.form-block legend,
.form-label {
  display: block;
  margin-bottom: 6px;
  padding: 0;
  font-size: var(--st-fs-2xs);
  font-weight: var(--fw-bold);
  letter-spacing: .07em;
  text-transform: uppercase;
  color: var(--color-ink-soft);
}

.num-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.stepper {
  display: flex;
  gap: 6px;
}

.stepper .step-btn {
  width: var(--tap-target);
  height: auto;
  min-height: var(--tap-target);
}

.num-input {
  flex: 1;
  min-width: 0;
  width: 100%;
  min-height: var(--tap-target);
  padding: 6px 8px;
  font: var(--fw-bold) var(--st-fs-lg) var(--font-mono);
  text-align: center;
  color: var(--color-ink);
  background: var(--color-surface);
  border: var(--border-width) solid var(--color-border-strong);
  border-radius: var(--radius-sm);
  -moz-appearance: textfield;
  appearance: textfield;
}

.num-input::-webkit-outer-spin-button,
.num-input::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

.num-input:focus {
  outline: none;
  border-color: var(--color-accent);
  box-shadow: 0 0 0 var(--focus-width) var(--color-focus);
}

.num-input.is-small {
  flex: none;
  width: 3.6em;
  min-height: 38px;
  font-size: var(--st-fs-md);
}

.field-hint {
  margin-top: 4px !important;
  font-size: var(--st-fs-2xs);
  font-weight: var(--fw-bold);
  color: var(--color-ink-muted);
}

.choice-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
}

.choice-grid.is-row {
  grid-template-columns: repeat(auto-fit, minmax(6.5em, 1fr));
}

.choice {
  display: flex;
  flex-wrap: wrap;           /* wrap, never spill out of the pop-up */
  min-width: 0;
  align-items: center;
  gap: 8px;
  min-height: var(--tap-target);
  padding: 6px 10px;
  font-size: var(--st-fs-sm);
  font-weight: var(--fw-bold);
  color: var(--color-ink);
  background: var(--color-surface);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
}

.choice:hover {
  border-color: var(--color-border-strong);
  background: var(--color-surface-2);
}

.choice:has(input:checked) {
  border-color: var(--color-accent);
  background: var(--color-accent-soft);
  box-shadow: inset 0 0 0 1px var(--color-accent);
}

.choice:has(input:disabled) {
  opacity: .45;
  cursor: not-allowed;
}

.choice input[type="radio"] {
  flex: none;
  width: 1.1em;
  height: 1.1em;
  margin: 0;
  accent-color: var(--color-accent);
}

.choice.is-wide {
  grid-column: 1 / -1;
}

.choice .math {
  font-family: var(--font-mono);
}

.chips {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 8px;
}

.chip {
  min-height: 36px;
  padding: 0 12px;
  font: var(--fw-bold) var(--st-fs-sm) var(--font-mono);
  color: var(--color-accent-strong);
  background: var(--color-accent-soft);
  border: var(--border-width) solid var(--color-accent);
  border-radius: var(--radius-pill);
  cursor: pointer;
}

.chip:hover {
  background: var(--color-accent);
  color: var(--color-on-accent);
}

.rule-box {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 4px 10px;
  margin-top: 14px;
  padding: 10px 12px;
  background: var(--color-surface-2);
  border: var(--border-width) solid var(--color-border-soft);
  border-radius: var(--radius-sm);
}

.rule-box .form-label {
  margin: 0;
}

.rule-out {
  min-width: 0;
  overflow-wrap: anywhere;
  font: var(--fw-bold) var(--st-fs-lg) var(--font-mono);
  color: var(--color-ink);
}

.modal-msg {
  min-height: 1.4em;
  margin-top: 8px !important;
  font-size: var(--st-fs-xs);
  font-weight: var(--fw-bold);
  line-height: 1.45;
  color: var(--color-ink-muted);
}

.modal-msg.is-error {
  color: var(--color-danger);
}

.modal-msg.is-warn {
  color: var(--color-warning);
}

.help-list {
  margin: 10px 0 0;
  padding-left: 22px;
}

.help-list li {
  margin-bottom: 8px;
}

/* ---------------- Scrollbars ---------------- */

.tool-frame ::-webkit-scrollbar {
  width: 13px;
  height: 13px;
}

.tool-frame ::-webkit-scrollbar-track {
  background: var(--color-surface-2);
}

.tool-frame ::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border: 3px solid var(--color-surface);
  border-radius: 999px;
}

/* ---------------- Narrow and phone screens ---------------- */

@media (max-width: 1100px) and (min-aspect-ratio: 4/3) {
  .move-sub {
    display: none;
  }
}

@media (max-width: 760px) {
  .tool-frame {
    height: auto;
    overflow: visible;
  }

  .app-header {
    height: auto;
    min-height: var(--header-h);
    padding: 8px 12px;
    flex-wrap: wrap;
  }

  .brand-text p {
    display: none;
  }

  .header-actions .btn {
    padding-inline: .8em;
  }

  .layout {
    grid-template-columns: minmax(0, 1fr);
    grid-template-rows: none;
  }

  .panel-graph { order: 1; }
  .panel-moves { order: 2; }
  .panel-info  { order: 3; max-height: 75vh; }

  /* the plane is as wide as the screen; the head and status add to it */
  .graph-body {
    height: min(calc(100vw - 2 * var(--pad) - 16px), 70vh);
    flex: none;
  }

  .moves-list {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .moves-note {
    font-size: var(--st-fs-xs);
  }

  #popBtn {
    display: none;
  }

  .move-sub {
    display: none;
  }

  .undo-btn {
    margin-top: 0;
  }

  .seg span {
    padding: 0 .6em;
  }

  .zoom-picker {
    margin-left: 0;
  }

  .modal-backdrop.is-side {
    justify-items: center;
    align-items: end;
    padding: 12px;
  }
}

@media (max-width: 420px) {
  .seg svg {
    display: none;
  }

  .num-grid,
  .choice-grid {
    grid-template-columns: minmax(0, 1fr);
  }
}

@media (prefers-contrast: more) {
  :root {
    --grid: #6b7a8f;
    --grid-five: #3f4c5e;
  }

  .panel,
  .modal {
    box-shadow: none;
  }
}

/* "the line y = mx + b" box in the Reflect form */
.num-input.is-eq {
  flex: 1;
  min-width: 0;
  min-height: 38px;
  font-size: var(--st-fs-md);
  text-align: left;
}