How to fix this code? It does not scale my images - html

Question

I have this piece of code. It doesn't scale my images to this size.
Height and width doesn't work. Why?
in style.css i have this line:
.gallery-popup .image-container img{width: 100%; height: auto; display: block;}
<div class="trace">
<img src="img/content/Imagesall/13347.jpg" height="250" width="250" alt="" />
<div class="tagline">
<div class="content">
<div class="title">TITLE</div>
<div class="description">TEXT</div>
</div>
</div>
</div>
<div class="overflow">
<div class="swiper-container" data-autoplay="0" data-loop="1" data-speed="500" data-center="0" data-slides-per-view="1">
<div class="swiper-w">
<div class="swiper-s">
<div class="image-container">
<img src="img/content/Imagesall/13347.jpg" height="250" width="250" alt="" />
<div class="description">
<div class="title">titletext</div>
<div class="text">texttexttext.</div>
</div>
</div>
</div>

Answer 1

Without any css to look in is this the responsive css for <img> images. Give the img a width and set the height to auto. You do not have to use the height and width in the html, use the css to give a width only
<div class="trace">
<img src="img/content/Imagesall/13347.jpg" alt="" />
.trace img {
width: ...; /* use for example px or % */
max-width: 100%;
height: auto; /* this line to preserve width:height ratio */
border: 0; /* remove default border of img */
}