opencode/packages/ui/src/components/file-icon.css

[data-component="file-icon"] {
  flex-shrink: 0;
  width: 16px;
  height: 16px;
}

/*
  File tree: show monochrome weak icons by default.
  On hover, show the original file-type colors.
*/
[data-component="filetree"] .filetree-icon--mono {
  color: var(--icon-base);
}

[data-component="filetree"] .filetree-iconpair {
  position: relative;
  display: inline-flex;
  width: 16px;
  height: 16px;
}

[data-component="filetree"] .filetree-iconpair [data-component="file-icon"] {
  position: absolute;
  inset: 0;
}