Summary

When $theme-site-margins-width receives custom values, it can cause the the content inside the alert component to overlap or become misaligned with the banner and other components. For example, setting $theme-site-margins-width: 1px results in the following:

Setting the value to $theme-site-margins-width: 15` results in the following:

And $theme-site-margins-width: 6`:

We should recalculate the padding and margins on this component so that they consistently align with the other components that use $theme-site-margins-width.