add test for gap in flex display mode

site/_static/scripts/browser-support.js

@@ -199,6 +199,26 @@ function themeSupport(urlRoot) {
 //     return query.split(/[^A-Za-z0-9_]+/g).filter(function(term) { return term; });
 // }
 
+function flexGapSupport() {
+    // create flex container with row-gap set
+    var flex = document.createElement("div");
+    flex.style.display = "flex";
+    flex.style.flexDirection = "column";
+    flex.style.rowGap = "1px";
+
+    // create two, elements inside it
+    flex.appendChild(document.createElement("div"));
+    flex.appendChild(document.createElement("div"));
+
+    // append to the DOM (needed to obtain scrollHeight)
+    document.body.appendChild(flex);
+    var isSupported = flex.scrollHeight === 1; // flex container should be 1px high from the row-gap
+    flex.parentNode.removeChild(flex);
+
+    return isSupported;
+  }
+
+
 function browserSupport() {
     var urlRoot = document.getElementById("documentation_options").getAttribute('data-url_root');
     webpSupport();

site/conf.py

@@ -40,7 +40,7 @@
 html_css_files = ['styles/leftfield.css']
 # searchtools.js is a theme script that is always incuded, but is specified here to make sure it is 
 # listed in the html before browser-support.js, which uses it. 
-# html_js_files = ['scripts/browser-support.js']
+html_js_files = ['scripts/browser-support.js']
 html_context = {'default_mode': 'auto'}  # use the system/browser light/dark theme setting
 # html_favicon = '_static/favicons/favicon.svg'
 html_sourcelink_suffix = ''