@IanS Well, that's pretty odd. There appears to be a class in one of your content element divs in the header type pages that is targeted by script to become nearly opaque when you scroll down the page. Why this class is necessary at all is a bit of a mystery and why it extends from the top of the page header to the bottom of the page is equally a mystery. Did someone modify the default html code in the page header for this theme? This behavior doesn't make any sense.
You can fix this with a minor code change to the page header but, if the code was in fact altered in some way or you implemented a dodgy plugin, you'll first want to reverse those changes.
To eliminate the opacity/scroll issue, you should simply eliminate the class from the affected header div. To do this, in the Site Editor, click on "Theme" in the top navigation bar then click the "Edit HTML/CSS" button at the bottom of the left-hand sidebar. This will take you to the Code Editor.
- In the left-hand sidebar, you'll see the "Header Type" section right at the top. Look for "header.html" below that title and click on it.
- The html code for that page header type will appear in the window in the right pane. Click on the magnifying glass icon at the top of the window and enter the search term below:
<div class="wsite-elements wsite-not-footer wsite-header-elements">
- Delete the last class "wsite-header-elements" from that div (highlighted in red above).
- Save the change (click the blue Save button in the upper-right corner) and then republish your site.
