仅在桌面上滚动淡入淡出

Question

我的目标是仅在dekstop上查看页面时，才通过CSS将淡出效果赋予3个元素。所以我尝试了即使在移动设备上也可以使用的代码，我不知道为什么width函数不起作用。你能帮我吗？

this.specVars = { 
  taxinfoFormHelpTitle4 : 'title 4', 
  taxinfoFormHelpTitle5 : 'title 5', 
  taxinfoFormHelpTitle6 : 'title 6', 
  cityMissing : 'error city', 
  rgba_000000 : "rgba(0, 0, 0, 1)", //Black 
  rgba_000000_0 : "rgba(0, 0, 0, 0)", //Transparent 
  rgba_222222 : "rgba(34, 34, 34, 1)", //Dark gray 
  rgba_2ba6cb : "rgba(43, 166, 203, 1)", 
  rgba_336699 : "rgba(51, 102, 153, 1)", //Blue 
  bold : "700" };
var colors = this.specVars;

var keys = Object.keys(colors);

for (var key of keys){

  if(colors[key].includes('rgba') && colors[key].includes(', 1)')){

    colors[key]= colors[key].replace(', 1)', ')');

    colors[key] = colors[key].replace('rgba', 'rgb');

  };
}

console.log(colors)