Here is some custom css to style the comment thread on the Elegant Themes DIVI theme.

.single-post .comment-body {padding-left: 0; padding-right: 0;}
.single-post .et_pb_button::after, .single-post .et_pb_button::before{content: none;}
.single-post #comment-wrap .comment-reply-link.et_pb_button {position: absolute; top: 100%;}
.single-post #commentform .form-submit .et_pb_button:hover {color: #000 !important; background-color: #fff !important; border: 2px solid #000 !important;}