Missing word wrapping rules?

Still testing this theme out but I think it’s missing word wrapping rules in the CSS. Text copy-pasted from elsewhere shows up fine but text typed into the post editor overflows. I added the following code in the CSS and everything works fine now:

.entry-content, .entry-summary, .page-content, .comment-content {
    -moz-hyphens: auto;
    word-wrap: break-word;
}