Multiple UI Improvements (#4069)

Minor contast fix for file uploading text.

Updating icon markup

Fixing icon for mentions

Removing irrelevant characters

Updating closing tag for mentions icon

webapp/utils/utils.jsx

@@ -489,7 +489,7 @@ export function applyTheme(theme) {
         changeCss('.app__body .sidebar--left .nav-pills__container li>h4, .app__body .sidebar--left .add-channel-btn', 'color:' + changeOpacity(theme.sidebarText, 0.6), 1);
         changeCss('.app__body .sidebar--left .add-channel-btn:hover, .app__body .sidebar--left .add-channel-btn:focus', 'color:' + theme.sidebarText, 1);
         changeCss('.app__body .sidebar--left .status .offline--icon', 'fill:' + theme.sidebarText, 1);
-        changeCss('@media(max-width: 768px){.app__body .modal .settings-modal .settings-table .nav>li>a', 'border-color:' + changeOpacity(theme.sidebarText, 0.2), 2);
+        changeCss('@media(max-width: 768px){.app__body .modal .settings-modal .settings-table .nav>li>a, .app__body .sidebar--menu .divider', 'border-color:' + changeOpacity(theme.sidebarText, 0.2), 2);
     }
 
     if (theme.sidebarUnreadText) {
@@ -577,7 +577,7 @@ export function applyTheme(theme) {
 
     if (theme.centerChannelColor) {
         changeCss('.app__body .post-list__arrows, .app__body .post .flag-icon__container', 'fill:' + changeOpacity(theme.centerChannelColor, 0.3), 1);
-        changeCss('.app__body .channel-header__links .icon, .app__body .sidebar--right .sidebar--right__subheader .usage__icon', 'fill:' + theme.centerChannelColor, 1);
+        changeCss('.app__body .modal .status .offline--icon, .app__body .channel-header__links .icon, .app__body .sidebar--right .sidebar--right__subheader .usage__icon', 'fill:' + theme.centerChannelColor, 1);
         changeCss('@media(min-width: 768px){.app__body .post:hover .post__header .col__reply, .app__body .post.post--hovered .post__header .col__reply', 'border-color:' + changeOpacity(theme.centerChannelColor, 0.2), 2);
         changeCss('.app__body .sidebar--left, .app__body .sidebar--right .sidebar--right__header, .app__body .suggestion-list__content .command', 'border-color:' + changeOpacity(theme.centerChannelColor, 0.2), 1);
         changeCss('.app__body .post.post--system .post__body', 'color:' + changeOpacity(theme.centerChannelColor, 0.6), 1);