By default the DIVI blog category page style is basic. You can see an example in the picture below from the TweakDorks website.

By adding this in the custom css section in the theme options you can improve the style of your DIVI blog pages.

.archive img[width="1080"] {
max-width: 300px;
float: left;
margin-right: 20px;
.archive .et_pb_post {
border-top: 5px solid #F13361;
box-shadow: 0 0 10px #ddd;
padding: 10px;

Here is an example: