Hi there!
Sorry for the delayed response.
You can try the following code in your custom CSS:
.article-list .article .article-intro-image img, .article-list .article .article-featured-video img, .article-list .article .article-featured-audio img, .article-list .article .article-feature-gallery img {
height: 400px;
It will give you same height for all of your slider images. Please use your desired height value.
Note: Path towards custom CSS(Joomla 3): Extensions>Templates>Styles> Click on your current default template name then choose Template Options. Then find custom CSS within the custom code.
Best Regards