Missing breadcrumb nth-child CSS rule.

Problem/Motivation

On documentation pages, breadcrumbs that reach 4 children in length currently have incomplete CSS rules, missing a rule for nth-child(4) background-color.

Steps to reproduce

Visit any page in documentation with 4 breadcrumb links.

Proposed resolution

Add the following CSS:

.breadcrumb span:nth-child(4) {
background-color: #064771;
}

Remaining tasks

Update CSS.

User interface changes

Update CSS.

API changes

None.

Data model changes

None.