Comment Form broken

Hello Support,
the default comment form of my blog seems to be ok.
Please see here:
http://www.eymann.info/download/form_ok.png
But when I reply on a given comment the form is broken. The field alignment is scrambled.
Please see here:
http://www.eymann.info/download/form_broken.png

The URL of the site is: https://www.videospielgeschichten.de/mea-culpa-kingdom-come-deliverance/#comments

Maybe it has something to do with some style changes in have in my child theme css.
Therefore i list my custom.css here:

/* Have fun adding your style here :) - PS: At all times this file should contain a comment or a rule, otherwise opera might act buggy :( */

/* General Custom CSS */

/* Standard comment text */
#top .comment_text {
font-size: 14px;
}

/* Category title */
.custom-cat-title {
font-family: Roboto;
font-size: 30px;
letter-spacing: 2px;
text-transform: uppercase;
}

/* Category link color */
/*.blog-categories a {
	color:#02a8e8 !important;
}*/

/* Latest comments */
#top .recentcomments {
font-size: 14px;
}

/* Submit buttons */
input[type="submit"]{
font-size: 14px !important;
}

/* Comment reply */
#top .comment-reply-link {
font-size: 14px;
}

/* Meta info post */
.html_elegant-blog #top .post-entry .minor-meta {
font-size: 13px !important;
}

/* Meta info blog grid */
.html_elegant-blog #top .slide-meta-comments {
font-size: 13px !important;
}

.html_elegant-blog #top .slide-meta-del {
font-size: 13px !important;
}

.html_elegant-blog #top .slide-meta-time {
font-size: 13px !important;
}

/* Comment author name */
.html_elegant-blog #top .comment_author_name {
text-transform:uppercase !important;
}

/* Comment meta info */
.html_elegant-blog #top .comment-meta {
font-size: 13px !important;
}

/* Post grid h3 */
h3.slide-entry-title{
font-size: 1.3em !important;
}

/* Reading time not on pages*/
.page .rt-reading-time {
    display: none !important;
}

/* Reading time formatting*/
.rt-reading-time {
font-size: 13px !important;
margin-top:15px;margin-bottom:15px;
}

/* Blog post */
.html_modern-blog #top .post-entry .post-meta-infos {
    float: none;
}

/* Align meta infos under post title */
.html_modern-blog #top.single-post .post-entry .post-meta-infos {
margin-top: 0px !important;
padding: 0px !important;
top: -22px !important;
}

/* Blog post image */
.html_elegant-blog #top.single-post .entry-content-wrapper .big-preview.single-big {
   margin-top: 0px !important; 
   margin-bottom: 30px !important; 
   padding-bottom: 0px !important;
}

.page-thumb {
   margin-top: 0px !important; 
   margin-bottom: 30px !important; 
   padding-bottom: 0px !important;
}

/* Dropcap at post beginning */
.vsg_big_letter {
  float: left;
  font-family: Georgia;
  font-size: 70px;
  line-height: 60px;
  padding-top: 2px;
  padding-right: 10px;
  padding-left: 1px;
}

/* Show page image in full size */
.page-thumb img {
 width:100% !important;
}

/* Author bio description */
.single .author_description_text p {
    margin-bottom: 50px;
}

@media only screen and (min-width: 768px) {
.single .author_description_text p {
    margin-left: 130px;
    margin-right: 50px;
    }
}

/* Do not show sidebar on mobile */
@media only screen and (max-width: 990px) {
#top #main .sidebar { display: none !important; }
.content { width: 100% !important; border: none !important; }
}

/* Magazine style formatting */
#top .av-magazine-content-wrap {
    min-height: 161px;
}
#top .av-magazine-thumbnail img {
    width: 100%;
}
#top .av-magazine-thumbnail {
    width: 161px;
    min-height: 161px;
}
#top .av-magazine-time {
    float: right;
}

/* Comment content and gravatar */
#top .comment_content {
    margin: 0;
    padding: 0;
}

#top .gravatar {
    float: none;
    margin-bottom: 20px;
}

#top .comment_content {
    position: relative;
    overflow: visible;
}

#top .comment-header {
    position: absolute;
    left: 80px;
    top: -70px;
}

#top .commentlist ul {
    margin: 0 0 0 34px;
}

/* Align meta infos under post title (for landing page) */
.html_modern-blog #top.page-template-default .post-entry .post-meta-infos {
margin-top: 0px !important;
padding: 0px !important;
 top: -22px !important; 
}
.html_modern-blog #top.page-template-default .entry-content-wrapper .big-preview.single-big {
    margin-top: 0px !important; 
    padding-bottom: 0px !important;
}

/* Pagination meta info */
#top .main_color .pagination .pagination-meta{
font-size: 14px;
}

#top .main_color .pagination .current{
font-size: 14px;
}

#top .main_color .pagination .inactive{
font-size: 14px;
}

/* Removing Excerpt Text from Grid Style Blog Page
.slide-entry-excerpt {
    display: none !important;
}
 */

/*
Desktop Styles
================================================== */
/* Note: Add new css to the media query below that you want to only effect the desktop view of your site */

@media only screen and (min-width: 768px) {
  /* Add your Desktop Styles here */

/* Sidebar */
.sidebar_right .comment_container {
    padding-right: 50;
}

}

/*
Mobile Styles
================================================== */
/* Note: Add new css to the media query below that you want to only effect the Mobile and Tablet Portrait view */

@media only screen and (max-width: 767px) {
  /* Add your Mobile Styles here */

/* Sidebar */
.sidebar_right .comment_container {
    padding-right: 0;
}

/* Sticky header on mobile */
@media only screen and (max-width: 767px) {
  .responsive #top #main {
    /* Margin top value should be equal to header height*/
    margin-top: 50px;
  }
  .responsive #top #wrap_all #header {
    position: fixed;
  }
}

}

Please give me advise.
Kind regards
Andre