@wordpress/block-library/build-style/tab/editor-rtl.css

Block library for the WordPress editor.

.wp-block-tab.is-selected {
  outline-offset: 2px;
}

.block-editor-block-preview__live-content:has(.wp-block-tab) {
  flex-basis: inherit !important;
  flex-grow: inherit !important;
}
.block-editor-block-preview__live-content:has(.wp-block-tab) .wp-block-tab {
  flex-basis: 100% !important;
}