1. 1 core/modules/comment/css/comment.css
  2. 1 core/themes/basis/css/component/comment.css
.comment {
  position: relative;
  display: block;
  padding: 0;
  margin: 0 0 1.5em;
}

.comments .indented {
  position: relative;
  padding-left: 1.25em;
  margin-top: -1.5em;
}

.comments .indented:before,
.comments .indented:after {
  content: '';
  position: absolute;
  display: block;
  border: 0.125em solid transparent;
}

.comments .indented:before {
  top: -1em;
  left: 0;
  width: 0.5em;
  height: 1.5em;
  border-left-color: #dee2ea;
  border-bottom-color: #dee2ea;
}

.comments .indented:after {
  content: '';
  position: absolute;
  top: 0.6875em;
  left: 0.4375em;
  width: 0.25em;
  height: 0.25em;
  border-top-color: #dee2ea;
  border-right-color: #dee2ea;
  transform: rotate(45deg);
  transform-origin: right top;
}

[dir="rtl"] .comment {
  padding: 0;
}

.comment-header {
  position: relative;
}

.comment-header:before {
  content: "";
  position: absolute;
  top: 100%;
  left: 1.625em;
  width: 0.875em;
  height: 0.875em;
  display: block;
  border: 0.125em solid transparent;
  border-bottom-color: #dee2ea;
  border-left-color: #dee2ea;
  transform: rotate(-45deg) translate(0, -0.75em);
  background: #ffffff;
  pointer-events: none;
  z-index: 0;
}

[dir="rtl"] .comment:before {
  right: 1.625em;
  left: auto;
}

.comment .attribution {
  position: relative;
  z-index: 1;
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-pack: start;
  -ms-flex-pack: start;
  justify-content: flex-start;
  -webkit-box-align: center;
  -ms-flex-align: center;
  align-items: center;
  padding: 0 0 0.5em;
}

[dir="rtl"] .comment .attribution {
  -webkit-box-pack: end;
  -ms-flex-pack: end;
  justify-content: flex-end;
}

.comment .attribution img {
  display: block;
}

.comment .user-picture {
  width: 3.25em;
  padding: 0 0.75em 0 0;
}

.commenter-name {
  margin: 0;
}

.commenter-name a {
  text-decoration: none;
}

.commenter-name a:hover {
  text-decoration: underline;
}

.comment .comment-text {
  border: 0.125em solid #dee2ea;
}

.comment-title {
  padding: 1em 1.25em 0.25em;
}

.comment-title h3 {
  margin: 0;
  padding: 0;
  font-size: 1.125em;
}

.comment-time {
  padding: 0;
  font-size: 0.875em;
}

.comment .content {
  padding: 0 1.375em;
}

.comment-footer {
  float: right;
  margin: 0 -0.125em 0 0;
  padding: 0.5em 0.5em;
  background: #dee2ea;
}

.comment-footer .links.inline li {
  margin: 0;
  padding: 0 0.5em; /* Ensure spacing on login links */
}

.comment-footer .links.inline li:after {
  display: none;
}

.comment-footer .links.inline a{
  display: inline-block;
  margin: 0 -0.5em; /* Prevent spacing on log in message */
  padding: 0 0.5em;
}
.comment-footer .links.inline a:hover {
  text-decoration: underline;
}

[dir="rtl"] .comment-footer {
  float: left;
}

a.comment-permalink  {
  width: .7em;
  height: .7em;
  padding: .1em;
  display: inline-block;
  background-color: currentColor;
  -webkit-mask-image: url("../../images/link-icon.svg");
  mask-image: url("../../images/link-icon.svg");
  -webkit-mask-size: cover;
  mask-size: cover;
  margin: 0 0 0 0.5em;
}

File

core/themes/basis/css/component/comment.css