#visual-under { position: relative; }

#circle {
  -webkit-border-radius: 50%;
  border-radius: 50%;
  position: absolute;
  top: 44px;
  right: 0;
  bottom: 0;
  left: 0;
  margin: auto;
  background: rgba( 0, 0, 0, .8 );

}
#logo {
  position: absolute;
  top: 44px;
  right: 0;
  bottom: 0;
  left: 0;
  margin: auto;
background: transparent url( ../images/logo-markw.png ) no-repeat center center;
  background-size: 60% 60%;
}

@media (max-width: 768px) {

    #visual-under {
        width: 100%;
        height: 50vh;
        min-height: 360px;
    }
    #circle {
        width: 160px;
        height: 160px;
    }
    #logo {
        width: 160px;
        height: 160px;
  background: transparent url( ../images/logo-markw.png ) no-repeat center center;
  background-size: 70% 70%;
    }

} /* end -768px */

@media (min-width: 769px) {

    #visual-under {
        width: 100%;
        height: 50vh;
        min-height: 480px;
    }
    #circle {
        width: 240px;
        height: 240px;
    }
    #logo {
        width: 240px;
        height: 240px;
  background: transparent url( ../images/logo-markw.png ) no-repeat center center;
  background-size: 60% 60%;
    }

} /* 769px- */