Simplify emoji rendering (#34048)

It seems like most of our custom styles around the .emoji class are
useless and we can just make them render like any other text. Rendering
should now match GitHub.

Fixes: #34019

Also see #11541 and
#12317 for some context. I think
browser emoji rendering has improved in recent years so these hacks are
no longer needed.

---------

Co-authored-by: wxiaoguang <[email protected]>

Author: silverwind

web_src/css/base.css

@@ -989,14 +989,7 @@ table th[data-sortt-desc] .svg {
   box-shadow: 0 0 0 1px var(--color-secondary) inset;
 }
 
-.emoji {
-  font-size: 1.25em;
-  line-height: var(--line-height-default);
-  font-style: normal !important;
-  font-weight: var(--font-weight-normal) !important;
-  vertical-align: -0.075em;
-}
-
+/* for "image" emojis like ":git:"  ":gitea:" and ":github:" (see CUSTOM_EMOJIS config option) */
 .emoji img {
   border-width: 0 !important;
   margin: 0 !important;

web_src/css/markup/content.css

@@ -336,11 +336,6 @@
   padding-right: 28px;
 }
 
-.markup .emoji {
-  max-width: none;
-  vertical-align: text-top;
-}
-
 .markup span.frame {
   display: block;
   overflow: hidden;