.ckeditor5-toolbar-button-bold {
  background-image: url(../icons/bold.svg);
}

.ckeditor5-toolbar-button-italic {
  background-image: url(../icons/italic.svg);
}

.ckeditor5-toolbar-button-underline {
  background-image: url(../icons/underline.svg);
}

.ckeditor5-toolbar-button-code {
  background-image: url(../icons/code.svg);
}

.ckeditor5-toolbar-button-strikethrough {
  background-image: url(../icons/strikethrough.svg);
}

.ckeditor5-toolbar-button-subscript {
  background-image: url(../icons/subscript.svg);
}

.ckeditor5-toolbar-button-superscript {
  background-image: url(../icons/superscript.svg);
}