Testimonial element cuts off text on smartphones when assigning it fixed height

Hello support!

So I placed a customer reviews / testimonials element inside my clients page, which made all elements beneath on the page constantly move up and down – depending on the size of the testimonial text.

So I changed this and set a fixed position by putting this code into the Quick CSS:

.avia-slider-testimonials .avia-testimonial-content {
height: 130px;
}

This works fine, however now when I look at the page on smartphones it cuts off some of the testimonial text. How can I make this work in responsive mode – so that the text is shown on desktop, tablets and smartphones and still retaining a fixed position that doesn’t cause the whole layout to jump up and down?

Thank you!