style.admin.css

.ckeditor5-toolbar-button-style {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 110px;
  color: #000;
}

.ckeditor5-toolbar-button-style::before {
  margin-left: 10px;
  /* For browsers which don't support alt content, eg FireFox */
  content: "Style";
  content: "Style" / "";
  font-size: 14px;
}

[dir="rtl"] .ckeditor5-toolbar-button-style::before {
  margin-right: 10px;
  margin-left: 0;
}

.ckeditor5-toolbar-button-style::after {
  display: inline-block;
  width: 7px;
  height: 7px;
  margin-right: 10px;
  content: "";
  transform: rotate(135deg);
  border-width: 2px 2px 0 0;
  border-style: solid;
}

[dir="rtl"] .ckeditor5-toolbar-button-style::after {
  margin-right: 0;
  margin-left: 10px;
}

File

core/modules/ckeditor5/css/style.admin.css

View source 
  1. .ckeditor5-toolbar-button-style {

  2.   display: flex;

  3.   align-items: center;

  4.   justify-content: space-between;

  5.   width: 110px;

  6.   color: #000;

  7. }

  8. 

  9. .ckeditor5-toolbar-button-style::before {

  10.   margin-left: 10px;

  11.   /* For browsers which don't support alt content, eg FireFox */

  12.   content: "Style";

  13.   content: "Style" / "";

  14.   font-size: 14px;

  15. }

  16. 

  17. [dir="rtl"] .ckeditor5-toolbar-button-style::before {

  18.   margin-right: 10px;

  19.   margin-left: 0;

  20. }

  21. 

  22. .ckeditor5-toolbar-button-style::after {

  23.   display: inline-block;

  24.   width: 7px;

  25.   height: 7px;

  26.   margin-right: 10px;

  27.   content: "";

  28.   transform: rotate(135deg);

  29.   border-width: 2px 2px 0 0;

  30.   border-style: solid;

  31. }

  32. 

  33. [dir="rtl"] .ckeditor5-toolbar-button-style::after {

  34.   margin-right: 0;

  35.   margin-left: 10px;

  36. }