discourse/app/assets/stylesheets/common/admin/schema_field.scss

.schema-field {
  margin-bottom: 1em;

  .schema-field__input {
    input {
      margin-bottom: 0;
    }

    margin-bottom: 0.3em;
  }

  .schema-field__description {
    font-size: var(--font-down-1);
    color: var(--primary-medium);
  }
}