How to round images?

Question

css

Why if you take such a piece of html code

<div class="reviews__avatar">
    <img src="img/feed-photo-1.jpg" alt="" class="reviews__avatar-pic">
</div>

and apply css to it

.reviews__avatar {
    width: 150px;
    height: 150px;
    border-radius: 50%;
}

then the images are not rounded?

Answer 1

or
.reviews__avatar{
overflow: hidden;
}

Answer 2

Are you setting the border radius without specifying the border itself? And how do you think it should work?
Just specify the color width and border style.