Search and Diff CSS enhancements (#14050)

* Search and Diff CSS enhancements

- Use flexbox for language stats
- Improve labels and code boxes on repo and code search
- Use flexbox on diff header and improve suppressed diff text
- Add dedicated color for diff expander

* more diff tweaks, less vertical padding on header

* more minor tweaks

* always show fold icon, image diff improvments

* remove margin

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

web_src/less/_explore.less

@@ -15,39 +15,32 @@
 
 .ui.repository.list {
   .item {
-    padding-bottom: 25px;
+    padding-bottom: 1.5rem;
 
     &:not(:first-child) {
       border-top: 1px solid var(--color-secondary);
-      padding-top: 25px;
+      padding-top: 1.5rem;
     }
 
     .ui.header {
       font-size: 1.5rem;
-      padding-bottom: 10px;
+      margin-bottom: .5rem;
 
       .name {
         word-break: break-all;
       }
 
       .metas {
-        color: #888888;
         font-size: 14px;
-        font-weight: normal;
-
-        span:not(:last-child) {
-          margin-right: 5px;
-        }
       }
     }
 
     .time {
       font-size: 12px;
-      color: #808080;
     }
 
     .ui.tags {
-      margin-bottom: 1em;
+      margin-bottom: .5rem;
     }
   }
 }