fleet/frontend/components/YamlAce/_styles.scss

.yaml-ace {
  max-height: 408px;
  &__wrapper {
    &--error {
      .ace-fleet {
        border: 1px solid $ui-error;
      }
    }
    &--disabled {
      @include disabled($allow-pointer-events: true);
    }
  }

  // Added to remove the "popping" effect when the editor first loads.
  min-height: 408px;

  .ace_gutter-layer {
    min-height: 408px;
  }

  .ace_line {
    min-height: 24px;
  }

  .ace_gutter-cell {
    min-height: 24px;
  }

  .ace_fold-widget {
    min-height: 24px;
  }
}