excalidraw/src/components/ToolIcon.scss

.ToolIcon {
  display: inline-block;
  position: relative;
  font-family: Cascadia;
  cursor: pointer;
}

.ToolIcon__icon {
  background-color: #e9ecef;

  width: 2.5rem;
  height: 2.5rem;

  display: flex;
  justify-content: center;
  align-items: center;

  border-radius: var(--space-factor);

  svg {
    position: relative;
    height: 1em;
  }
}

.ToolIcon_size_s .ToolIcon__icon {
  width: 1.4rem;
  height: 1.4rem;
  font-size: 0.8em;
}

.ToolIcon_type_button {
  padding: 0;
  border: none;
  margin: 0;
  font-size: inherit;

  &:hover .ToolIcon__icon {
    background-color: #e9ecef;
  }
  &:active .ToolIcon__icon {
    background-color: #ced4da;
  }
  &:focus .ToolIcon__icon {
    box-shadow: 0 0 0 2px #a5d8ff;
  }
}

.ToolIcon_type_radio,
.ToolIcon_type_checkbox {
  position: absolute;
  opacity: 0;

  &:hover + .ToolIcon__icon {
    background-color: #e9ecef;
  }
  &:checked + .ToolIcon__icon {
    background-color: #ced4da;
  }
  &:focus + .ToolIcon__icon {
    box-shadow: 0 0 0 2px #a5d8ff;
  }
}

.ToolIcon.ToolIcon__lock {
  display: flex;
  align-items: center;
  justify-content: center;
  margin-left: 0.1rem;

  .ToolIcon__icon {
    background-color: transparent;
    width: 2rem;
    height: 2em;
  }
  &:hover .ToolIcon__icon {
    background-color: transparent;
  }
  &:active .ToolIcon__icon {
    background-color: transparent;
  }
  &:focus .ToolIcon__icon {
    box-shadow: none;
  }
}

.ToolIcon__keybinding {
  position: absolute;
  bottom: 2px;
  right: 3px;
  font-size: 0.5em;
  color: #adb5bd; // OC GRAY 5
  font-family: Arial, Helvetica, sans-serif;
}