<!DOCTYPE html>编程狮(w3cschool.cn)name="viewport" content="width=device-width, initial-scale=1"rel="stylesheet" href="https://7npmedia.w3cschool.cn/w3.css"class="w3-xxlarge"class="w3-container w3-black w3-text-blue-grey"黑底蓝灰字.class="w3-container w3-gray w3-text-blue-grey"灰底蓝灰字.class="w3-container w3-text-blue-grey"白底蓝灰字.