Clarify media query using .02px and bump from callout to warning

site/content/docs/4.3/layout/breakpoints.md

@@ -173,7 +173,7 @@ These mixins take those declared breakpoints, subtract `.02px` from them, and us
 // No media query since the xxl breakpoint has no upper bound on its width
 {{< /highlight >}}
 
-{{< callout info >}}
+{{< callout warning >}}
 {{< partial "callout-info-mediaqueries-breakpoints.md" >}}
 {{< /callout >}}
 

site/layouts/partials/callout-info-mediaqueries-breakpoints.md

-Note that since browsers do not currently support [range context queries](https://www.w3.org/TR/mediaqueries-4/#range-context), we work around the limitations of [`min-` and `max-` prefixes](https://www.w3.org/TR/mediaqueries-4/#mq-min-max) and viewports with fractional widths (which can occur under certain conditions on high-dpi devices, for instance) by using values with higher precision for these comparisons.
+**Why subtract .02px?** Browsers don't currently support [range context queries](https://www.w3.org/TR/mediaqueries-4/#range-context), so we work around the limitations of [`min-` and `max-` prefixes](https://www.w3.org/TR/mediaqueries-4/#mq-min-max) and viewports with fractional widths (which can occur under certain conditions on high-dpi devices, for instance) by using values with higher precision.