理想实现效果：

1.注册界面的实现

<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>注册界面</title><link rel="stylesheet" href="RESETCSS.css"><style>div{width: 300px;height: 350px;border: 1px solid grey;margin: 8px 0 0 8px;}span{border-bottom: 3px solid purple;padding-bottom: 3px;}a{text-decoration: none;float: right;padding-top: 3px;color: deepskyblue;}.first{width: 290px;height: 30px;border: 1px solid grey;border-radius: 5px;margin: 5px 4px;}.second{width: 200px;height: 30px;border: 1px solid grey;border-radius: 5px;margin: 5px 4px;}.third{width: 79px;height: 30px;border: 1px solid blue;border-radius: 5px;color: blue;}.fourth{width: 79px;height: 30px;border: 1px solid blue;border-radius: 5px;vertical-align: middle;background-image: url("https://ss1.bdstatic.com/70cFvXSh_Q1YnxGkpoWK1HF6hhy/it/u=1378353400,959510337&fm=26&gp=0.jpg");background-size: 79px 30px;}.zc{width: 290px;height: 30px;border: 1px solid grey;border-radius: 5px;margin: 5px 4px;background-color: skyblue;color: white;}</style></head><body><div><form action=""><span>请注册</span><a href="">立即登录&lt;</a><hr><input type="text" class="first" placeholder="请输入手机号"><br><input type="text" class="second" placeholder="请输入短信验证码"><input type="button" class="third" value="发送验证码"><br><input type="text" class="first" placeholder="请输入用户名"><br><input type="password" class="first" placeholder="请输入密码"><br><input type="password" class="first" placeholder="请再次输入密码"><br><input type="text" class="second" placeholder="请输入图形验证码"><input type="button" class="fourth"><br><input type="submit" class="zc" value="立即注册"><br></form></div></body></html>

效果如下：

2.登录界面的实现

<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>登录</title><style>div{width: 200px;height: 180px;border: 1px solid grey;padding: 8px 8px;}.reg{border-bottom: 3px solid purple;padding-bottom: 6px;}a{float: right;text-decoration: none;color: skyblue;}.first{width: 200px;height: 25px;border: 1px solid grey;border-radius: 2px;margin: 5px 0;}.second{font-size: 9px;position: relative;bottom: 4px;}.pwd{float: right;font-size: 10px;margin: 3px;}.reg2{width: 200px;height: 25px;border: 1px solid grey;border-radius: 2px;margin: 5px 0;background-color: skyblue;color: white;}</style></head><body><div><form action=""><span class="reg">请登录</span><a href="">立即注册&lt;</a><hr><input type="text" class="first" placeholder="请输入手机号"><br><input type="password" class="first" placeholder="请输入密码"><br><input type="checkbox"><span class="second">七天内自动登录</span><a href="" class="pwd">忘记密码?</a><br><input type="submit" class="reg2" value="登录"></form></div></body></html>