How the problem of an element size being too small for its content can be solved (box model)?

The overflow CSS shorthand property sets the desired behaviour for an element's overflow — i.e. when an element's content is too big to fit in its block formatting context — in both directions.

/* Keyword values */
overflow: visible;
overflow: hidden;
overflow: clip;
overflow: scroll;
overflow: auto;
overflow: hidden visible;

/* Global values */
overflow: inherit;
overflow: initial;
overflow: unset;

Source: https://developer.mozilla.org/en-US/docs/Web/CSS/overflow