{{ $featured_image := .Param "featured_image" }}
{{ $featured_image := (trim $featured_image "/") | absURL }}
<header class="cover bg-top" style="background-image: url('{{ $featured_image }}');">
  <div>
    <div class="tc-l pv4 pv6-l ph3 ph4-ns">
      <h1 class="f2 f-subheadline-l fw3 white-90 mb0 lh-title">
        {{ .Title | default .Site.Title }}
      </h1>
      {{ with .Params.description }}
      <h2 class="fw1 f5 f3-l white-80 measure-wide-l center mt3">
        {{ . }}
      </h2>
      {{ end }}
    </div>
  </div>
</header>

{{ $featured_image := .Param "featured_image" }}
{{ $featured_image := (trim $featured_image "/") | absURL }}
<header class="cover bg-top" style="background-image: url('{{ $featured_image }}');">
  <div>
    <div class="tc-l pv4 pv6-l ph3 ph4-ns">
      <h1 class="f2 f-subheadline-l fw3 white-90 mb0 lh-title">
        {{ .Title | default .Site.Title }}
      </h1>
      {{ with .Params.description }}
      <h2 class="i fw1 f5 f3-l white-80 measure-wide-l center mt3">
        {{ . }}
      </h2>
      {{ end }}
    </div>
  </div>
</header>

Change description style to italics
Change description style to italics
