Media library admin styles

Drupal ckedtor media library modal too small

 The Media Library window that pops up in the content editor is really small by default.

Here is what it looks like in the Seven theme.

Drupal media library seven theme

media-library.css

/web/themes/custom/mantratheme/css/media-library.css 
.ui-dialog--narrow.media-library-widget-modal {
  max-width: 64em;
  margin: 1em;
}

.media-library-views-form {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
}

.media-library-views-form .media-library-item {
  flex-grow: 1;
  max-width: 24%;
  margin-bottom: .5em;
  padding: .5em .5em .5em 2em;
  position: relative;
  box-sizing: border-box;
  border: 1px solid black;
}

.media-library-views-form .media-library-item--disabled {
  border: 1px solid #AAA;
}

.media-library-views-form .media-library-item__preview {
  text-align: center;
}

.media-library-views-form .media-library-item__preview img {
  height: 8em;
  object-fit: contain;
  object-position: center center;
  margin-bottom: .5em;
}

.views-field-media-library-select-form {
  position: absolute;
  top: 0;
  left: 0;
}

.views-field-media-library-select-form .form-item {
  margin: 1em;
}
Libraries override 
libraries-override:
  classy/media_library:
    css:
      layout:
        css/layout/media-library.css: css/media-library.css
Drupal mantra admin theme media library baisc