Overlay + WET theme: Changed overlay header background colour to #2E5274 so stands out more against background
Merge pull request #4073 from pjackson28/changeoverlayheadercolour

Overlay + WET theme: Changed overlay header background colour to #2E5274 so stands out more against background
Updated build version to v4.0.0-b1-development
Merge pull request #4074 from patheard/optimize-toggle

Toggle: changed aria init to function call
WET theme: Cleaned up appearance of mobile panel
Merge pull request #4076 from pjackson28/cleanupwetthememobilepanelappearance

WET theme: Cleaned up appearance of mobile panel
WET theme: Removed h1 font-size override (fixes #3905)
Merge pull request #4077 from pjackson28/removedwetthemeh1fontoverride

WET theme: Removed h1 font-size override
WET theme: Cleaned up the appearance of the secondary menu
Merge pull request #4078 from pjackson28/wetthemecleanedupsecmenu

WET theme: Cleaned up the appearance of the secondary menu
WET theme: Added ability to include/exclude various page sections using front matter
WET theme: Removed font-size override for site menu sub-menu links
Merge pull request #4079 from pjackson28/cleanupdefaulthbslogic

WET theme: Added ability to include/exclude various page sections using front matter
Merge pull request #4080 from pjackson28/removesitemenusubmenufontsizewettheme

WET theme: Removed font-size override for site menu sub-menu links
Details/summary polyfill: Moved demo CSS to demos CSS file and added left padding to the summary of example 2
Merge pull request #4081 from pjackson28/addedemorepaddingdetailssummaryexample

Details/summary polyfill: Moved demo CSS to demos CSS file and added left padding to the summary of example 2
[CSS] Fixed the discrepency in button heights on Firefox.
[CSS] Removed underline for button links.
Tabs / Toggle: Fixed overly greedy selectors in Tabs and Toggle that interfered with nested details element
Merge pull request #4086 from pjackson28/fixnesteddetails

Tabs / Toggle: Fixed overly greedy selectors in Tabs and Toggle that interfered with nested details element