<svg width="1056" height="816" fill="none" xmlns="http://www.w3.org/2000/svg">
  <path fill="{color_background}" d="M0 0v816h1056V0z"/>
  <path transform="matrix(0 1 1 0 0 0)" fill="url(#a)" fill-opacity=".5" d="M0 0h816v1056H0z"/>
  <defs>
    <linearGradient id="a" x1="0" y1="0" x2="816" y2="1056" gradientUnits="userSpaceOnUse">
      <stop offset=".3" stop-color="{color_background}"/>
      <stop offset="1" stop-color="{color_accent}"/>
    </linearGradient>
  </defs>
</svg>