@media(max-width:1000px){
    nav ul li::before{
        content: "";
        width: 15px;
        height: 15px;
        display: block;
        float: left;
        margin: 2px 5px 0 0;
    }
    nav ul li:nth-child(1)::before{
        background: url('../images/home.png') no-repeat;
        background-size: cover;
    }
    nav ul li:nth-child(2)::before{
        background: url('../images/pdf.png') no-repeat;
        background-size: cover;
    }
    nav ul li:nth-child(3)::before{
        background: url('../images/people.png') no-repeat;
        background-size: cover;
    }
    nav ul li:nth-child(4)::before{
        background: url('../images/people.png') no-repeat;
        background-size: cover;
    }
    nav ul li:nth-child(5)::before{
        background: url('../images/register.png') no-repeat;
        background-size: cover;
    }
    nav ul li:nth-child(6)::before{
        background: url('../images/paper.png') no-repeat;
        background-size: cover;
    }
    nav ul li:nth-child(7)::before{
        background: url('../images/hotel.png') no-repeat;
        background-size: cover;
    }
    nav ul li:nth-child(8)::before{
        background: url('../images/down.png') no-repeat;
        background-size: cover;
    }
    nav ul li:nth-child(9)::before{
        background: url('../images/contact.png') no-repeat;
        background-size: cover;
    }
}