body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: #f2f2f2;
    padding: 0;
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    box-sizing: border-box;
}

.container {
    background: #fff;
    box-shadow: 0px 0px 25px 0px rgba(0, 0, 0, 0.1);
    padding: 40px;
    border-radius: 10px;
}

#result {
    font-size: 1.2em;
    font-weight: bold;
    color: #444;
    margin-bottom: 20px;
    text-align: center;
}

#header {
    font-size: 2em;
    font-weight: bold;
    color: #444;
    margin-bottom: 20px;
    text-align: center;
}

input[type="datetime-local"],
button {
    display: block;
    width: 100%;
    border: 1px solid #ddd;
    margin: 10px 0;
    padding: 15px;
    box-sizing: border-box;
}

button {
    background-color: #4CAF50;
    color: white;
    cursor: pointer;
    border: none;
    transition: all 0.3s ease-in-out;
}

button:hover {
    background-color: #45a049;
}

button:active {
    transform: scale(0.98);
}

@media only screen and (max-width: 600px) {
    .container {
        width: 80%;
    }
}