.top_block {margin: 0 auto;width:1080px;text-align:center;}
.top_block ul {list-style: none;padding:0;margin:0}
.top_block li {float: left;padding:0;margin:0}

@media screen and (max-width: 1000px) {
body { min-width:768px;}
.top_block {width: 760px;}
}

@media screen and (max-width: 788px) {
body { min-width:620px;}
.top_block {width: 610px;}
}

@media screen and (max-width: 620px) {
body { min-width:500px;}
.top_block {width: 490px;}
}

@media screen and (max-width: 520px) {
body { min-width:300px;}
.top_block {width: 300px;}
}