html{
    height:100%;
}
body{
    margin:0;
    padding:0;
    height:100%;
    width:100%;
    display:table;
}
.main {
    width: 100%;
    height: 100%;
    background-image: url('Images/main-bg.png');
    background-repeat: no-repeat;
    background-size: contain;
    background-position: center center;
    text-align: center;
    display: table-cell;
    vertical-align: middle;
}
.item {
    width: CALC(100% - 30px);
    height: CALC(100% / 3 - 15px);
    display: block;
    background: #49454a;
    /*border: 1px solid black;*/
    border-radius: 20px;
    opacity: 0.85;
    text-decoration: none;
    margin: auto auto;
    border: 5px solid #fff;
}
    .item > span {
        background: none;
        font-family: 'Larsseit Bold';
        font-size: 60px;
        color: #fff;
        text-align: center;
        line-height: CALC(100% / 3 + 150px);
    }
.insaat:hover {
    background-image: url('Images/insaat.jpg');
    background-repeat: no-repeat;
    background-position:0px 0px;
    background-size: cover;
    cursor: pointer;
}
.bilgisayar:hover {
    background-image: url('Images/bilgisayar.jpg');
    background-repeat: no-repeat;
    background-position: 0px 0px;
    background-size: cover;
    cursor: pointer;
}
.yazilim:hover {
    background-image: url('Images/yazilim.jpg');
    background-repeat: no-repeat;
    background-position: 0px 0px;
    background-size: cover;
    cursor: pointer;
}

@media screen and (min-width: 900px) {
    body {
        display: block;
    }

    .main {
        display: block;
    }
    .item {
        width: CALC((100% - 600px) / 3);
        height: CALC(100% - 4px);
        display: inline-block;
        background: #49454a;
        /*border: 1px solid black;*/
        border-radius: 20px;
        transform: skewX(-10deg);
        opacity: 0.85;
        text-decoration: none;
        margin:0;
        border:0;
    }
        .item > span {
            position: absolute;
            top: 0;
            left: CALC(50% + 47px);
            background: none;
            transform-origin: 0 0;
            transform: rotate(90deg);
            font-family: 'Larsseit Bold';
            font-size: CALC(100% * 3);
            color: #fff;
            text-align: center;
            line-height: 2;
            padding-left:25px;
        }
    .insaat:hover {
        background-image: url('Images/insaat.jpg');
        background-repeat: no-repeat;
        background-position: -200px 0px;
        background-size: cover;
        cursor: pointer;
    }
    .bilgisayar:hover {
        background-image: url('Images/bilgisayar.jpg');
        background-repeat: no-repeat;
        background-position: -300px 0px;
        background-size: cover;
        cursor: pointer;
    }
    .yazilim:hover {
        background-image: url('Images/yazilim.jpg');
        background-repeat: no-repeat;
        background-position: -350px 0px;
        background-size: cover;
        cursor: pointer;
    }
}