function getStylesheet() {
  var currentTime = new Date().getHours();
  if (0 <= currentTime&&currentTime < 6) {
    document.write("<link rel='stylesheet' href='times/night.css' type='text/css'>");
  }
  if (6 <= currentTime&&currentTime < 10) {
    document.write("<link rel='stylesheet' href='times/morning.css' type='text/css'>");
  }
  if (10 <= currentTime&&currentTime < 18) {
    document.write("<link rel='stylesheet' href='times/day.css' type='text/css'>");
  }
  if (18 <= currentTime&&currentTime < 22) {
    document.write("<link rel='stylesheet' href='times/evening.css' type='text/css'>");
  }
  if (22 <= currentTime&&currentTime <= 24) {
    document.write("<link rel='stylesheet' href='times/night.css' type='text/css'>");
  }
}
getStylesheet();