.tile {
  background-size: cover;
  height: 350px;
  position: relative;
}
    
    #pet1 {
    background-image: url("../assets/images/petrietce/Petrie\ Tce.jpg");

    }
    
    #pet2 {
    background-image: url("../assets/images/petrietce/Petrie\ Tce\ 1.jpg");

    }
    
    #pet3 {
    background-image: url("../assets/images/petrietce/Petrie\ Tce\ 2.jpg");

    }

    #pet4 {
    background-image: url("../assets/images/petrietce/Petrie\ Tce\ 3.jpg");

    }

    #pet5 {
      background-image: url("../assets/images/petrietce/Petrie\ Tce\ 4.jpg");

      }

    #pet6 {
      background-image: url("../assets/images/petrietce/AJ5319.jpg");
    }

    #pet7 {
      background-image: url("../assets/images/petrietce/AJ5363.jpg");
    }

    #pet8 {
      background-image: url("../assets/images/petrietce/AJ5385.jpg");
    }

    #pet9 {
      background-image: url("../assets/images/petrietce/AJ5432.jpg");
    }

    #pet10 {
      background-image: url("../assets/images/petrietce/AJ5456.jpg");
    }

    #pet11 {
      background-image: url("../assets/images/petrietce/AJ5493.jpg");
    }

    #pet12 {
      background-image: url("../assets/images/petrietce/AJ5536.jpg");
    }

    #pet13 {
      background-image: url("../assets/images/petrietce/AJ5588_89_90.jpg");
    }

    #pet14 {
      background-image: url("../assets/images/petrietce/AJ5595.jpg");
    }

    #pet15 {
      background-image: url("../assets/images/petrietce/AJ5627.jpg");
    }

    #pet16 {
      background-image: url("../assets/images/petrietce/AJ5641.jpg");
    }

    #pet17 {
      background-image: url("../assets/images/petrietce/AJ5659.jpg");
    }

    #pet18 {
      background-image: url("../assets/images/petrietce/AJ5789.jpg");
    }

    #pet19 {
      background-image: url("../assets/images/petrietce/AJ5801.jpg");
    }

    @media only screen and (max-width: 350px) {
        .cover-heading {
            font-size: 3em;
        }
      
        .navbar-brand {
          width:50%;
        }
      
        .masthead-brand {
          width:50%;
          height:50%;
        }
      
        .inner img {
          width: 120px;
        }
      }