* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: "Microsoft YaHei", sans-serif;
    background: linear-gradient(120deg, #3498db, #8e44ad);
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.login-container {
    background: rgba(255, 255, 255, 0.9);
    padding: 40px;
    border-radius: 10px;
    box-shadow: 0 15px 25px rgba(0, 0, 0, 0.2);
    width: 400px;
}

.login-box h2 {
    text-align: center;
    color: #2c3e50;
    margin-bottom: 30px;
}

.input-group {
    position: relative;
    margin-bottom: 30px;
}

.input-group input {
    width: 100%;
    padding: 10px 0;
    font-size: 16px;
    color: #2c3e50;
    border: none;
    border-bottom: 2px solid #2c3e50;
    outline: none;
    background: transparent;
    transition: 0.3s;
}

.input-group label {
    position: absolute;
    top: 0;
    left: 0;
    padding: 10px 0;
    font-size: 16px;
    color: #2c3e50;
    pointer-events: none;
    transition: 0.3s;
}

.input-group input:focus ~ label,
.input-group input:valid ~ label {
    top: -20px;
    color: #3498db;
    font-size: 12px;
}

.input-group input:focus,
.input-group input:valid {
    border-bottom: 2px solid #3498db;
}

button {
    width: 100%;
    padding: 12px;
    background: #3498db;
    color: #fff;
    border: none;
    border-radius: 5px;
    font-size: 16px;
    cursor: pointer;
    transition: 0.3s;
}

button:hover {
    background: #2980b9;
    transform: translateY(-2px);
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.login-box {
    animation: fadeIn 0.8s ease-out;
}