.mask-top-left {
  -webkit-mask: url("data:image/svg+xml;utf8,<svg viewBox='0 0 200 112.5' xmlns='http://www.w3.org/2000/svg'><path fill='black' d='M100,12v6c0,6.6-5.4,12-12,12H12C5.4,30,0,35.4,0,42v58.5c0,6.6,5.4,12,12,12h176c6.6,0,12-5.4,12-12V12c0-6.6-5.4-12-12-12h-76C105.4,0,100,5.4,100,12z'/></svg>") no-repeat center / contain;
          mask: url("data:image/svg+xml;utf8,<svg viewBox='0 0 200 112.5' xmlns='http://www.w3.org/2000/svg'><path fill='black' d='M100,12v6c0,6.6-5.4,12-12,12H12C5.4,30,0,35.4,0,42v58.5c0,6.6,5.4,12,12,12h176c6.6,0,12-5.4,12-12V12c0-6.6-5.4-12-12-12h-76C105.4,0,100,5.4,100,12z'/></svg>") no-repeat center / contain;
}