metamask-extension/ui/app/css/itcss/components/header.scss

.app-header {
  align-items: center;
  visibility: visible;
  background: rgb(239, 239, 239);
  padding-top: 1.5vh;
  height: 12vh;
  max-height: 60px;
  position: relative;
  z-index: 12;
  padding: 6px 8px;
  // background: #EFEFEF; // $gallery

  @media screen and (max-width: 575px) {
    position: fixed;
    height: 34px;
    width: 100%;
    box-shadow: 0px 2px 2px 1px rgba(0, 0, 0, 0.08);
    z-index: 30;
  }
}

.app-header h1 {
  font-family: 'Montserrat Regular';
  text-transform: uppercase;
  color: #22232C; // $shark
}

h2.page-subtitle {
  font-family: 'Montserrat Regular';
  text-transform: uppercase;
  color: #AEAEAE;
  font-size: 1em;
  margin: 12px;
}

.network-component-wrapper {
  display: flex;
  flex-direction: row;
  align-items: center;

  @media screen and (min-width: 576px) {
    margin-bottom: 1.8em;
  }
}

.left-menu-wrapper {
  display: flex;
  flex-direction: row;
  align-items: center;

  @media screen and (min-width: 576px) {
    margin-bottom: 1.8em;
  }
}