Changed sidebar close button to Bootstrap

app/assets/javascripts/leaflet.layers.js

@@ -22,9 +22,8 @@ L.OSM.layers = function (options) {
       .attr("class", "sidebar_heading")
       .appendTo($ui)
       .append(
-        $("<span>")
-          .text(I18n.t("javascripts.close"))
-          .attr("class", "icon close")
+        $("<button type='button' class='btn-close float-end mt-1'>")
+          .attr("aria-label",I18n.t("javascripts.close"))
           .bind("click", toggle))
       .append(
         $("<h4>")

app/assets/stylesheets/common.scss

@@ -633,11 +633,6 @@ body.compact-nav {
   padding: $lineheight/2 $lineheight;
   // background: $offwhite;
   // border-bottom: 1px solid $grey;
-  > .close {
-    float: right;
-    margin-top: 2px;
-    cursor: pointer;
-  }
 }
 
 #browse_status {