WordPress/wp-includes/blocks/post-featured-image/editor.css

.wp-block-post-featured-image .block-editor-media-placeholder{
  -webkit-backdrop-filter:none;
          backdrop-filter:none;
  z-index:1;
}
.wp-block-post-featured-image .components-placeholder,.wp-block-post-featured-image .wp-block-post-featured-image__placeholder{
  align-items:center;
  justify-content:center;
  min-height:200px;
  padding:0;
}
.wp-block-post-featured-image .components-placeholder .components-form-file-upload,.wp-block-post-featured-image .wp-block-post-featured-image__placeholder .components-form-file-upload{
  display:none;
}
.wp-block-post-featured-image .components-placeholder .components-button,.wp-block-post-featured-image .wp-block-post-featured-image__placeholder .components-button{
  align-items:center;
  background:var(--wp-admin-theme-color);
  border-color:var(--wp-admin-theme-color);
  border-radius:50%;
  border-style:solid;
  color:#fff;
  display:flex;
  height:48px;
  justify-content:center;
  padding:0;
  position:relative;
  width:48px;
}
.wp-block-post-featured-image .components-placeholder .components-button>svg,.wp-block-post-featured-image .wp-block-post-featured-image__placeholder .components-button>svg{
  color:inherit;
}
.wp-block-post-featured-image .components-placeholder:where(.has-border-color),.wp-block-post-featured-image .wp-block-post-featured-image__placeholder:where(.has-border-color),.wp-block-post-featured-image img:where(.has-border-color){
  border-style:solid;
}
.wp-block-post-featured-image .components-placeholder:where([style*=border-top-color]),.wp-block-post-featured-image .wp-block-post-featured-image__placeholder:where([style*=border-top-color]),.wp-block-post-featured-image img:where([style*=border-top-color]){
  border-top-style:solid;
}
.wp-block-post-featured-image .components-placeholder:where([style*=border-right-color]),.wp-block-post-featured-image .wp-block-post-featured-image__placeholder:where([style*=border-right-color]),.wp-block-post-featured-image img:where([style*=border-right-color]){
  border-right-style:solid;
}
.wp-block-post-featured-image .components-placeholder:where([style*=border-bottom-color]),.wp-block-post-featured-image .wp-block-post-featured-image__placeholder:where([style*=border-bottom-color]),.wp-block-post-featured-image img:where([style*=border-bottom-color]){
  border-bottom-style:solid;
}
.wp-block-post-featured-image .components-placeholder:where([style*=border-left-color]),.wp-block-post-featured-image .wp-block-post-featured-image__placeholder:where([style*=border-left-color]),.wp-block-post-featured-image img:where([style*=border-left-color]){
  border-left-style:solid;
}
.wp-block-post-featured-image .components-placeholder:where([style*=border-width]),.wp-block-post-featured-image .wp-block-post-featured-image__placeholder:where([style*=border-width]),.wp-block-post-featured-image img:where([style*=border-width]){
  border-style:solid;
}
.wp-block-post-featured-image .components-placeholder:where([style*=border-top-width]),.wp-block-post-featured-image .wp-block-post-featured-image__placeholder:where([style*=border-top-width]),.wp-block-post-featured-image img:where([style*=border-top-width]){
  border-top-style:solid;
}
.wp-block-post-featured-image .components-placeholder:where([style*=border-right-width]),.wp-block-post-featured-image .wp-block-post-featured-image__placeholder:where([style*=border-right-width]),.wp-block-post-featured-image img:where([style*=border-right-width]){
  border-right-style:solid;
}
.wp-block-post-featured-image .components-placeholder:where([style*=border-bottom-width]),.wp-block-post-featured-image .wp-block-post-featured-image__placeholder:where([style*=border-bottom-width]),.wp-block-post-featured-image img:where([style*=border-bottom-width]){
  border-bottom-style:solid;
}
.wp-block-post-featured-image .components-placeholder:where([style*=border-left-width]),.wp-block-post-featured-image .wp-block-post-featured-image__placeholder:where([style*=border-left-width]),.wp-block-post-featured-image img:where([style*=border-left-width]){
  border-left-style:solid;
}
.wp-block-post-featured-image[style*=height] .components-placeholder{
  height:100%;
  min-height:48px;
  min-width:48px;
  width:100%;
}

div[data-type="core/post-featured-image"] img{
  display:block;
  height:auto;
  max-width:100%;
}