Creating max-width images is not dependent on the display, so setting it is redundant. Cleans up the comments and implementation of the mixin as well.
Fixes#20767
* Fixes#20775 without adding extra width and an important flag
* Since we're now getting the extend, we don't need the extra position relative
* rerrange
* getting min-height from the extend already
- Rather than mix multiple properties in our color utilities, this splits all color and all background utils into separate classes.
- Adds new .text-white class to help lighten text color for darker backgrounds
- Restores two-mixin approach to generating semantic grid columns (now with 'make-col-ready' and 'make-col')
- Removes need for .col-xs-12 by restoring the mass list of all grid tier classes to set position, min-height, and padding
- Adds an initial 'width: 100%' to flexbox grid column prep (later overridden by the column sizing in 'flex' shorthand or 'width') to prevent flexbox columns from collapsing in lower viewports
Refs #19990
Continues the degruntification process.
Also removes mq4-hover-shim for now,
since it doesn't yet implement the standard PostCSS plugin interface.
- Remove background-color from header and footer in inverse cards (fixes#19841)
- Update border override for header and footer in cards; only need to declare a new color
- Update the selector for targetting blockquote footers in cards
- Both classes do about the same thing, but with different names
- Clarifies docs for .m-x-auto requiring a fixed width block element for it to work
- Add missing heading for clearfix section in docs (unrelated)
- Flexbox responsive behavior fixed with specific .col-{breakpoint} classes now added
- Dropped the make-col mixin in favor of a column-basics placeholder that we can extend across our grid infrastructure
- Updated docs to use required .col-xs-12 (as a safeguard for when folks enable flexbox mode--this isn't necessary in default grid mode)
- Update flexbox grid docs to include responsive docs, tweak some other bits too
- Rename -height to -height-base to match other vars
- Drop use of -height across the board and rely on it to be inherited
- Adjust padding of .dropdown-header to account for different line-height of h6 heading element (this needs refactoring for variables and rems also)
