drupal/core/modules/contextual/css/contextual.module.css

/**
 * @file
 * Generic base styles for contextual module.
 */

.contextual-region {
  position: relative;
}
.contextual .trigger:focus {
  /* Override the .focusable position: static */
  position: relative !important;
}
.contextual-links {
  display: none;
}
.contextual.open .contextual-links {
  display: block;
}