[Павел Турченко]

var Num = document.body.clientWidth;
var width = +Num;
var display1 = document.getElementById("price").style.display;
       if (display1 == "none" && width >= 979) {
        	document.getElementById("myModal").style.height = 870 + "px";
        } else if (display1 == "none" && width < 979) {
        	document.getElementById("myModal").style.height = 1210 + "px";
       	};
 	document.getElementById("site").onclick = function height_modal(){
        	if (display1 == "none" && width >= 979) {
        		document.getElementById("price").style.display = "block";
                document.getElementById("myModal").style.height = 1010 + "px";
            } else if (display1 == "block" && width >= 979) {  
            	document.getElementById("price").style.display = "none";             
                document.getElementById("myModal").style.height = 870 + "px";
            } else if (display1 == "none" && width < 979) {
            	document.getElementById("price").style.display = "block";
                document.getElementById("myModal").style.height = 1330 + "px";
            } else if (display1 == "block" && width < 979) {
            	document.getElementById("price").style.display = "none"; 
                document.getElementById("myModal").style.height = 1210 + "px";
            }
        	};

в общем решил вот такой аброкадаброй...