Pure CSS Flip Animated Login Form

<div class="flip-front">
                <h2>Welcome Back</h2>
                <form action="#">
                    <div class="input-group">
                        <input type="email" placeholder="Email Address" required>
                    </div>
                    <div class="input-group">
                        <input type="password" placeholder="Password" required>
                    </div>
                    <button type="submit" class="btn">Login</button>
                </form>
                <div class="switch-text">
                    Don't have an account? <label for="flip-toggle">Sign Up</label>
                </div>
            </div>

<div class="flip-back">
                <h2>Create Account</h2>
                <form action="#">
                    <div class="input-group">
                        <input type="text" placeholder="Full Name" required>
                    </div>
                    <div class="input-group">
                        <input type="email" placeholder="Email Address" required>
                    </div>
                    <div class="input-group">
                        <input type="password" placeholder="Create Password" required>
                    </div>
                    <button type="submit" class="btn">Register</button>
                </form>
                <div class="switch-text">
                    Already have an account? <label for="flip-toggle">Login here</label>
                </div>
            </div>

</div>
    </div>
</div>

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', sans-serif;
}

body {
    background: linear-gradient(135deg, 
                #667eea 0%, #764ba2 100%);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    overflow: hidden;
}

.main-container {
    perspective: 1000px; 
}

#flip-toggle {
    display: none; 
}

.flip-card {
    width: 380px;
    height: 380px;
    position: relative;
}

.flip-card-inner {
    position: relative;
    width: 100%;
    height: 100%;
    text-align: center;
    transition: transform 0.8s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    transform-style: preserve-3d; 
}

#flip-toggle:checked + .flip-card .flip-card-inner {
    transform: rotateY(180deg);
}

/* 3. Front and Back Faces */
.flip-front, .flip-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden; 
    background-color: #ffffff;
    border-radius: 20px;
    padding: 40px;
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.2);
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.flip-back {
    transform: rotateY(180deg);
}

h2 {
    color: #333;
    margin-bottom: 25px;
    font-size: 28px;
}

.input-group {
    margin-bottom: 20px;
    text-align: left;
}

input {
    width: 100%;
    padding: 12px 15px;
    border: 1px solid #ddd;
    border-radius: 8px;
    outline: none;
    transition: border-color 0.3s;
}

input:focus {
    border-color: #667eea;
}

.btn {
    width: 100%;
    padding: 12px;
    background: #667eea;
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: bold;
    cursor: pointer;
    transition: background 0.3s;
    margin-top: 10px;
}

.btn:hover {
    background: #764ba2;
}

.switch-text {
    margin-top: 25px;
    font-size: 14px;
    color: #666;
}

.switch-text label {
    color: #667eea;
    font-weight: bold;
    cursor: pointer;
    text-decoration: underline;
}

- CSS Flip Animated Login Form

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