Cleanup the positioning the smileys in conversations.

im/themes/winstripe/instantbird/conv.css

@@ -41,11 +41,11 @@
 }
 
 .ib-img-smile {
-  margin-bottom: -3px;
+  vertical-align: text-bottom;
 }
 
 *:-moz-any-link .ib-img-smile {
   border: none;
   border-bottom: solid 1px;
-  margin-bottom: -2px;
+  margin-bottom: 1px;
 }

im/themes/winstripe/instantbird/messages/main.css

@@ -45,12 +45,7 @@ p {
   margin: 0px auto;
 }
 
-p img {
-  margin-bottom: -3px;
-}
-
 p *:-moz-any-link img {
-  border: none;
+  margin-bottom: 1px;
   border-bottom: solid 1px;
-  margin-bottom: -2px;
 }