maths-editor {
  /* ── Typography ───────────────────────────────────────────────────────────── */
  --me-font-family:        system-ui, sans-serif;
  --me-font-size:          1rem;
  --me-font-size-small:    0.875rem;
  --me-line-height:        1.6;

  /* ── Colours ──────────────────────────────────────────────────────────────── */
  --me-text-colour:          #1a1a1a;
  --me-background:           #ffffff;
  --me-selection-background: #b3d4fc;
  --me-caret-colour:         #1a1a1a;
  --me-placeholder-colour:   #888888;

  /* ── Border and shape ─────────────────────────────────────────────────────── */
  --me-border:        1px solid #e0e0e0;
  --me-border-radius: 6px;

  /* ── Focus ring ───────────────────────────────────────────────────────────── */
  --me-focus-ring: 0 0 0 3px rgba(74, 144, 226, 0.4);

  /* ── Layout ───────────────────────────────────────────────────────────────── */
  --me-padding:    0.5rem 0.75rem;
  --me-min-height: 3rem;

  /* ── Motion ───────────────────────────────────────────────────────────────── */
  --me-transition-duration: 120ms;

  /* ── Math island ──────────────────────────────────────────────────────────── */
  --me-math-island-background: transparent;
  --me-math-island-border:     none;
  --me-math-island-padding:    0.1em 0.3em;
  --me-math-island-focus-ring: 0 0 0 2px rgba(74, 144, 226, 0.4);

  display: block;
}

.me-content {
  font-family: var(--me-font-family);
  font-size: var(--me-font-size);
  line-height: var(--me-line-height);
  color: var(--me-text-colour);
  background: var(--me-background);
  padding: var(--me-padding);
  border: var(--me-border);
  border-radius: var(--me-border-radius);
  min-height: var(--me-min-height);
  caret-color: var(--me-caret-colour);
  box-sizing: border-box;
  outline: none;
  white-space: pre-wrap;
  word-break: break-word;
  overflow-wrap: break-word;
  transition: box-shadow var(--me-transition-duration) ease;
}

.me-content:focus {
  box-shadow: var(--me-focus-ring);
  border-color: #4a90e2;
}

.me-content::selection {
  background-color: var(--me-selection-background);
}

/* Placeholder shown via ::before when the me-empty class is present */
maths-editor.me-empty .me-content::before {
  content: attr(data-me-placeholder);
  color: var(--me-placeholder-colour);
  pointer-events: none;
  display: block;
  /* Sits in flow so it doesn't shift surrounding layout */
}

/* Readonly visual cue */
.me-content[contenteditable="false"] {
  background: #f9fafb;
  color: #6b7280;
  cursor: default;
}

/* ── Phase 3: Maths islands ───────────────────────────────────────────────── */

.me-math-island {
  display: inline-block;
  vertical-align: baseline;
  min-width: 1.5em;
  line-height: 1;
  user-select: none;
  background: transparent;
  border: none;
  border-radius: var(--me-border-radius);
  padding: var(--me-math-island-padding);
  --contains-highlight-background-color: var(--me-selection-background);
}

.me-math-island:focus-within {
  outline: 2px solid rgba(74, 144, 226, 0.7);
  outline-offset: 2px;
}

.me-math-island.me-island-selected {
  background: var(--me-selection-background);
  border-radius: 3px;
}

.me-math-island math-field {
  display: inline-block;
  pointer-events: auto;
  user-select: auto;
  background: transparent;
  border: none;
  outline: none;
}

/* Hide MathLive's virtual keyboard toggle and hamburger menu buttons */
math-field::part(virtual-keyboard-toggle),
math-field::part(menu-toggle) {
  display: none;
}

/* First-backspace/delete highlight — second press confirms deletion */
.me-math-island.me-island-pending-delete {
  outline: 2px solid #ef4444;
  border-radius: 3px;
  background: rgba(239, 68, 68, 0.10);
}