📚HTML
 
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>一个登录注册界面</title>
    <link rel="stylesheet" href="./style.css">
</head>
<body>
    <div class="container">
        
       <div class="login-box">
            <div class="apple-btn login-apple">
                <li class="red-btn"></li>
                <li class="yellow-btn"></li>
                <li class="green-btn"></li>
            </div>
            <div class="title">Login</div>
            <div class="input">
                <input type="text" id="login-user" placeholder="Input your username">
            </div>
            <div class="input">
                <input type="password" id="login-password" placeholder="Input your password">
            </div>
            <div class="btn login-btn">
                <span>登录</span>
            </div>
            <div class="change-box login-change">
                <div class="change-btn toSign">
                    <span>去注册</span>
                </div>
            </div>
       </div>
       
       <div class="sign-box">
            <div class="apple-btn sign-apple">
                <li class="red-btn"></li>
                <li class="yellow-btn"></li>
                <li class="green-btn"></li>
            </div>
            <div class="title">Sign</div>
            <div class="input">
                <input type="text" id="sign-user" placeholder="Have A Good Name?">
            </div>
            <div class="input">
                <input type="password" id="sign-password" placeholder="Keep Secret">
            </div>
            <div class="btn sign-btn">
                <span>注册</span>
            </div>
            <div class="change-box sign-change">
                <div class="change-btn toLogin">
                    <span>去登陆</span>
                </div>
            </div>
       </div>
    </div>
    <script src="./script.js"></script>
</body>
</html>
 
📚CSS
 
* {
    padding: 0px;
    margin: 0px;
}
html, body {
    height: 100%;
    width: 100%;
    background-image: linear-gradient(120deg, #A59ACA, #F7CDBC);
    overflow: hidden;
}
.container {
    position: absolute;
    height: 350px;
    width: 600px;
    background-color: rgba(255, 255, 255, .9);
    
    
    
    top: 50%;
    left: 50%;
    transform: translate(-50%, -30%);
    
    border-radius: 10px;
    box-shadow: 0px 0px 10px rgba(17, 39, 59, 0.8);
    border: 1px solid rgba(17, 39, 59, 1);
    overflow: hidden;
    
    box-sizing: border-box;
    
    opacity: 0;
    
    transition: 1s;
}
.container-show {
    transform: translate(-50%,-50%) ;
    opacity: 1;
}
.title {
    margin-top: 10px;
    position: relative;
    height: 40px;
    width: 100%;
    font-size: 30px;
    display: flex;
    justify-content: center;
    align-items: center;
    
    text-transform: uppercase;
    font-weight: 500;
    letter-spacing: 3px;
    transition: .4s;
}
.input {
    width: 400px;
    height: 45px;
    position: relative;
    margin: 40px auto;
}
input {
    position: relative;
    width: 100%;
    height: 100%;
    border: none;
    outline: none;
    padding-left: 15px;
    font-size: 16px;
    
    background-color: rgba(255, 255, 255, 0.4);
    
    border-radius: 45px;
    
    transition: .4s;
}
.btn {
    height: 50px;
    width: 160px;
    position: relative;
    margin: -10px auto;
    background-color: rgba(0, 0, 0, 0.1);
    border-radius: 20px;
    color: rgba(255, 255, 255, .4);
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    transition: .4s;
}
.change-box {
    position: absolute;
    
    height: 0px;
    width: 100%;
    
    clip-path: polygon(100% 50%, 50% 100%, 100% 100%);
    bottom: 0px;
    transition: .4s;
}
.change-btn {
    position: absolute;
    bottom: 30px;
    right: 40px;
    font-size: 20px;
    
    display: none;
    font-weight: 500;
}
.change-btn:hover {
    
    text-shadow: 0px 0px 3px rgba(200, 200, 200, .8);
    cursor: pointer;
}
.container:hover .title {
    
    font-size: 20px;
}
.container:hover input {
    
    transform: translate(0, -30%);
}
.container:hover .btn {
    
    height: 30px;
    width: 90px;
    transform: translate(0,-30%);
    font-size: 12px;
}
.container:hover .change-box {
    
    height: 200px;
}
.container:hover .change-btn {
    
    display: block;
}
.login-box {
    position: absolute;
    height: 100%;
    width: 100%;
    background-color: rgba(17, 39, 59, 0.8);
    transition: .4s;
    z-index: 1;
    
    transform-origin: 0 100%;
}
.login-box .title {
    color: white;
    text-shadow: 0px 0px 7px rgba(255, 255, 255, .9);
}
.login-box input:focus {
    box-shadow: 0 0 10px rgba(1,1,1, .8);
}
.login-box input {
    
    caret-color: white;
    color: rgba(255, 255, 255, 0.8);
}
.login-btn:hover {
    color: white;
    background-color: #57606f;
    box-shadow: rgba(0, 0, 0, 0.1);
    text-shadow: 0px 0px 2px rgba(0, 0, 0, 0.1);
}
.login-change {
    background-color: rgba(255, 255, 255, .8);
}
.sign-box {
    position: absolute;
    height: 100%;
    width: 100%;
    background-color: rgba(255, 255, 255, .8);
    transform-origin: 0 100%;
    
    transform: rotate(90deg);
    transition: .4s;
    z-index: 1;
}
.sign-box  .title {
    text-shadow: 0 0 10px rgba(200, 200, 200, .8);
    font-weight: 500;
}
.sign-box input {
    box-shadow: 0 0 3px black;
}
.sign-box .btn {
    color: black;
    background-color: #e1dddf;
    transition:.5s;
}
.sign-box .btn:hover {
    color: white;
    background-color: #4781C3;
}
.sign-change {
    background-color: rgba(17, 39, 59, 0.8);
}
.toLogin {
    color: white;
}
.apple-btn {
    position: absolute;
    height: 15px;
    width: 65px;
    top: 3px;
}
.apple-btn li{
    list-style: none;
    position: relative;
    height: 15px;
    width: 15px;
    border-radius: 15px;
    opacity: 0;
}
.login-apple li{
    left: 5px;
    float: left;
}
.sign-apple li {
    right: 5px;
    float: right;
}
.sign-apple {
    right: 5px;
}
li:nth-child(2) {
    margin: 0px 2px
}
.red-btn {
    background-color: #F03752;
    transition: .3s;
    transform: translate(0, -50%);
}
.yellow-btn {
    background-color: #F3993A;
    
    transition: .6s;
    transform: translate(0, -50%);
}
.green-btn {
    background-color: #108B96;
    transition: .9s;
    transform: translate(0, -50%);
}
.container:hover .red-btn {
    opacity: 1;
    transform: translate(0,0);
}
.container:hover .yellow-btn {
    opacity: 1;
    transform: translate(0,0);
}
.container:hover .green-btn {
    opacity: 1;
    transform: translate(0,0);
}
.animate_login {
    
    transform: rotate(-90deg);
}
.animate_sign {
    
    transform: rotate(0deg) !important;
}
 
📚JS
 
const getSelector = ele => {
    return typeof ele === "string" ? document.querySelector(ele) : "";
}
const containerShow = () => {
    var show = getSelector(".container")
    show.className += " container-show"
}
window.onload = containerShow;
((window, document) => {
    
    let toSignBtn = getSelector(".toSign"),
        toLoginBtn = getSelector(".toLogin")
        loginBox = getSelector(".login-box"),
        signBox = getSelector(".sign-box");
    toSignBtn.onclick = () => {
        loginBox.className += ' animate_login';
        signBox.className += ' animate_sign';
    }
    toLoginBtn.onclick = () => {
        loginBox.classList.remove("animate_login");
        signBox.classList.remove("animate_sign");
    }
})(window, document);