.form-group {
        margin-bottom: 20px;
    }

    label {
        display: block;
        font-weight: bold;
        margin-bottom: 5px;
    }

    input[type="text"],
    input[type="email"],
    input[type="tel"],
    textarea {
        width: 100%;
        padding: 10px;
        border: 1px solid #ccc;
        border-radius: 5px;
    }

    input[type="text"]:invalid,
    input[type="email"]:invalid,
    input[type="tel"]:invalid,
    textarea:invalid {
        border: 1px solid #ff0000;
    }

    input[type="text"]:valid,
    input[type="email"]:valid,
    input[type="tel"]:valid,
    textarea:valid {
        border: 1px solid #00cc00;
    }

    input[type="submit"] {
        background-color: #0077cc;
        color: #fff;
        padding: 10px 20px;
        border: none;
        border-radius: 5px;
        cursor: pointer;
    }

    input[type="submit"]:hover {
        background-color: #0055aa;
    }

    .success {
        color: #00cc00;
        font-weight: bold;
    }

    .error {
        color: #ff0000;
        font-weight: bold;
    }