Issue #2829185 by vaplas, Jo Fitzgerald, anmolgoyal74, chipway, gaurav.kapoor, mark_fullmer, amit.drupal, cilefen, longwave, xjm, wturrell, anavarre: Fix spelling errors in Drupal core comments

(cherry picked from commit 2dabd1de)

Issue #2866801 by harsha012, joelpittet, BrightBold, droplet, Akshay kashyap, arunkumark, bmx269: Update stylelint rules color-hex-length to be consistent with Drupal's CSS standards

Issue #2939940 by bmx269, joelpittet: Update stylelint rules color-hex-case 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

Issue #2878548 by alexpott, droplet, Cottser, idebr, joelpittet, xjm, martin107: Fix CSS whitespace issues

Revert "Issue #2486453 by LewisNyman, sqndr, heatherwoz, hylid, yoroy, Bojhan: Set maximum width on Seven"

This reverts commit a70a74fc.

Issue #2486413 by Manjit.Singh, vinmassaro, LewisNyman: Seven's primary tabs have incorrect spacing on narrow screens

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 #2337379 by skippednote, BarisW, derjochenmeyer, herom, ChandeepKhosa, kiliweb, sqndr, Palashvijay4 | LewisNyman: Rename 'branding' to 'content-header'.