/* The banner belongs to the header and never covers the navigation. */
.site-banner-cell {
  vertical-align: middle;
}

.site-banner {
  box-sizing: border-box;
  width: 100%;
  max-width: 728px;
  margin: 0 auto;
  padding: 0;
  border: 0;
  background: transparent;
}

.site-banner:empty {
  display: none;
}

.site-banner img,
.site-banner iframe {
  display: block;
  max-width: 100%;
  margin: 0 auto;
  border: 0;
}

.site-banner img {
  height: auto;
}