message: support overriding avatar background color from custom theme
diff: @@ -77,7 +77,9 @@ export function defaultAvatarUrlForString(s) {
  }
  const colorIndex = total % defaultColors.length;
  // overwritten color value in custom themes
  - const color = defaultColors[colorIndex];
  + const cssVariable = `--avatar-background-colors_${colorIndex}`;
  + const cssValue = document.body.style.getPropertyValue(cssVariable);
  + const color = cssValue || defaultColors[colorIndex];
  let dataUrl = colorToDataURLCache.get(color);
  if (!dataUrl) {
  dataUrl = urlForColor(color);
  