Issue #3405153 by Nitin shrivastava, sijumpk, smustgrave, larowlan: Contexual links should never be bold, unless the theme explicitly makes it so

Issue #3343212 by markconroy, andy-blum, bnjmnm, longwave, alexpott, lauriii, codexmas, harsha012, rpayanm, occupant, Mukeysh, leahtard, joelpittet: Update Core CSS to use double-colon for pseudo elements

Issue #2209063 by bnjmnm, Sam152, tarekdj, lauriii, Wim Leers, LewisNyman, quietone: Fix the flicker of the "active" icons when a high-latency user clicks on toolbar items

Issue #2866810 by BrightBold, harsha012, joelpittet: Update stylelint rule function-comma-space-after to be consistent with Drupal's CSS standards

Issue #2866809 by BrightBold: Update stylelint rule declaration-colon-space-after to be consistent with Drupal's CSS standards

Revert "Issue #2570681 by juanse254, AndreaD, giancarlosotelo, lucastockmann, edurenye: when admin toolbar-oriented vertically a div is over the options"

This reverts commit 2acfed87.

Issue #2570681 by juanse254, AndreaD, giancarlosotelo, lucastockmann, edurenye: when admin toolbar-oriented vertically a div is over the options

Issue #2078803 by Wim Leers, aspilicious, wmortada, Sumit kumar, mrjmd, John Cook: Change contextual links background color to match the styleguide

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

Needs more discussion.

This reverts commit b983fad1.

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

Issue #1879386 by LewisNyman, jessebeach, Wim Leers, tkoleary: Increase target size of contextual links on touch devices.

Issue #2054055 by seanr: Bartik inappropriately styles all links in the footer, rather than links inside blocks in the footer, breaking contextual links in the process.

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 #1847314 by oresh, jessebeach, mattimck, nod_: Fixed Reduce the dependency on JavaScript for the toolbar to display properly.

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

Issue #1363112 by mparker17, mgifford, tlattimore, Jacine, dcmouyard, bowersox, ry5n, ahdiaz: Simplify names of 'element-x' helper classes.

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