The page https://superset.wmcloud.org/superset/welcome/ has misplaced </head> and <body>-HTML Tags, causing my browser to show nothing
This is how the source of the page looks like:
…
<input
type="hidden"
name="csrf_token"
id="csrf_token"
value="<removed some longish string>"
>
</head>
<body >
…So, there is an <input>-Tag within the <head> section, where it sure should not be.

