[Bug] Embedded widget CSS breaks on sites with DOM sanitizing tools

[sanason]

First noticed on a site using a Salesforce Aura + Lightning Web Components (LWC) frontend framework. LWC implements Lightning Web Security Sanitization, which rewrites our <style> tag so that, for instance:

<style>
.fba-modal-dialog .usa-alert--success .usa-alert__body > * {
    margin-left: 2.5rem;
}
</style>

becomes

<style>
  .fba-modal-dialog .usa-alert--success .usa-alert__body &gt; *{
    margin-left:2.5rem;
  }
</style>