markup: improved markup CSS.

- remove odd image borders.

rhodecode/public/css/legacy_code_styles.less

@@ -163,9 +163,7 b' div.markdown-block h6 {'
 }
 
 div.markdown-block hr {
-    height: 1px;
     border: 0;
-    color: #CCCCCC;
     color: #e6e5e5;
     height: 3px;
     margin-bottom: 13px;
@@ -178,7 +176,6 b' div.markdown-block blockquote,'
 div.markdown-block dl,
 div.markdown-block li,
 div.markdown-block table {
-    margin: 15px 0 !important;
     margin: 3px 0px 13px 0px !important;
     color: #424242 !important;
     font-size: 13px !important;
@@ -189,7 +186,6 b' div.markdown-block table {'
 }
 
 div.markdown-block pre {
-  margin: 15px 0 !important;
   margin: 3px 0px 13px 0px !important;
   padding: .5em;
   color: #424242 !important;
@@ -200,13 +196,8 b' div.markdown-block pre {'
 }
 
 div.markdown-block img {
-        padding: 4px;
-        border: @border-thickness solid @grey5;
-        border: @border-thickness solid rgba(0, 0, 0, 0.2);
-        -webkit-box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
-        -moz-box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
-        box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
-        margin: 5px 0 0 0 !important;
+  border-style: none;
+  background-color: #fff;
 }
 
 div.markdown-block ul,