index.css

.react-wysiwyg-typescript-wrapper * {
  box-sizing: initial
}


.react-wysiwyg-typescript-toolbar {
  border: 1px solid #d9d9d9;
  border-radius: 2px;
  box-sizing: border-box;
}


.react-wysiwyg-typescript-toolbar .rdw-option-wrapper {
  border: none;
  min-width: 20px;
}


.react-wysiwyg-typescript-toolbar .rdw-dropdown-optionwrapper {
  width: 100%;
  background: white;
  border-radius: 0;
  max-height: 300px;
  overflow: auto;
  left: -1px;
}


.react-wysiwyg-typescript-toolbar .rdw-option-active,
.react-wysiwyg-typescript-toolbar .rdw-option-wrapper:hover {
  border-radius: 0;
  background: #FFC107;
  box-shadow: none;
}


.react-wysiwyg-typescript-editor {
  border: 1px solid #d9d9d9;
  padding: 10px;
  min-height: 160px;
  box-sizing: border-box;
  border-radius: 2px;
}