$(document).ready(function(){
var cores =['red','green','blue','yellow','#ff4d94','cyan'];
var x = 0;
$("#c1_1_button").click(function(){
$("#c1_1").css("background-color",cores[x]);
x=x+1;
if (x == cores.length){x=0};
});
$("#c2_1_button").click(function(){
$("#c2_1").css("background-color",cores[x]);
x=x+1;
if (x == cores.length){x=0};
});
$("#c3_1_button").click(function(){
$("#c3_1").css("background-color",cores[x]);
x=x+1
if (x == cores.length){x=0};
});
$("#c4_1_button").click(function(){
$("#c4_1").css("background-color",cores[x]);
x=x+1
if (x == cores.length){x=0};
});
});