Codepen example of borders, radius, containers, anchoring model:

Codepen example of underline links:

See the Pen Link / ALL CAPS Styling by David Carmona (@dcarmona) on CodePen.

Codepen example of a responsive multi-column layout/breakpoints:

See the Pen 3-column Grid Sandbox by David Carmona (@dcarmona) on CodePen.

Codepen example of a in-line image alignment:

See the Pen Example by David Carmona (@dcarmona) on CodePen.