Issue #2031641 by aburrows, lauriii, nlisgo, Pol, redsquid, tuutti, LewisNyman, akalata, agviu, kallehauge, _nolocation, rpayanm, saki007ster, mdrummond, RavindraSingh, brahmjeet789: Change active class to is-active

Issue #2309137 by longwave, sqndr | LewisNyman: Remove quotes from all background-image: url() properties.

Issue #1490402 by LewisNyman, nod_, mcjim, mdrummond, rteijeiro, jessebeach, Bojhan, ry5n: Redesign tabs and the content header.

Issue #1963886 by ry5n, jessebeach, dcrocks, Wim Leers: Use HiDPI icons in the toolbar to support scaling on different devices.

Issue #1938044 by hass, jessebeach, Dragan Eror: Fixed Prefix all toolbar classes to prevent theme clashes.

Issue #2015789 by fubhy, echoz, rteijeiro, LewisNyman, penyaskito: Remove language_css_alter() (RTL stylesheets) in favor of HTML 'dir' attribute.

Issue #1987066 by Kevin Morse, JohnAlbin, rteijeiro, echoz, ry5n: Rename files to match CSS file naming convention.

Issue #1940208 by pameeela, mgifford, echoz: Fixed Contrast for add & remove shortcut links on overlay not sufficient for WCAG - Regression.

Issue #1137920 by jessebeach, lewisnyman, tkoleary, Bojhan, webchick, benjifisher, nod_, sjbassett, kathryn531, effulgentsia, Everett Zufelt: fixed toolbar on small screen sizes and redesign toolbar for desktop.