Seahub UI (#5261)

* [top toolbar] fixed the position of the vertical line between 2 sides

- fixed it for all the pages
- removed the duplicated 'div.main-panel' in 'lib-content-view'

* [search] modified the UI

* [top toolbar] redesigned the notification

* [top toolbar] avatar & the triangle: modified the UI

* [left side panel] updated the UI; fixup & improvement

* [misc] modified links' color, op-icon, and etc.

* [misc] updated UI for share dialog, other dialogs, & 'more operations' dropdown

* [misc] UI: modified markdown side panels, comment panels, input/textarea placeholder

* ['user settings' page] modified UI

* [shared dir upload link page] modified the UI

* [user settings] modified the UI

* [user settings] fixup

* [seafile-ui.css] use an updated one (modified color of buttons)

frontend/src/components/common/account.js

@@ -144,7 +144,7 @@ class Account extends Component {
     return (
       <div id="account">
         <a id="my-info" href="#" onClick={this.onClickAccount} className="account-toggle no-deco d-none d-md-block" aria-label={gettext("View profile and more")}>
-          <span>{this.renderAvatar()}</span>
+          {this.renderAvatar()}
           <span className="fas fa-caret-down vam"></span>
         </a>
         <span className="account-toggle sf2-icon-more mobile-icon d-md-none" aria-label={gettext("View profile and more")} onClick={this.onClickAccount}></span>