Allow theming member info minimise button

res/css/views/rooms/_MemberInfo.scss

@@ -34,6 +34,10 @@ limitations under the License.
     height: 16px;
     padding: 10px 15px;
     cursor: pointer;
+    mask-image: url('$(res)/img/minimise.svg');
+    mask-repeat: no-repeat;
+    mask-position: center;
+    background-color: $rightpanel-button-color;
 }
 
 .mx_MemberInfo_name h2 {

src/components/views/rooms/MemberInfo.js

@@ -983,9 +983,10 @@ module.exports = withMatrixClient(React.createClass({
         return (
             <div className="mx_MemberInfo">
                     <div className="mx_MemberInfo_name">
-                        <AccessibleButton className="mx_MemberInfo_cancel" onClick={this.onCancel}>
-                            <img src={require("../../../../res/img/minimise.svg")} width="10" height="16" className="mx_filterFlipColor" alt={_t('Close')} />
-                        </AccessibleButton>
+                        <AccessibleButton className="mx_MemberInfo_cancel"
+                            onClick={this.onCancel}
+                            title={_t('Close')}
+                        />
                         { e2eIconElement }
                         <EmojiText element="h2">{ memberName }</EmojiText>
                     </div>