CSS ////////////////////////////////////////////////////////////////////////////////////////////////
.form-container {
    padding: 15vh 1vh;
    background-color: #cccccc;
}

form{
    margin-right: auto;
    margin-left: auto;
    width: 40vw;
    background-color: rgba(90, 99, 86, 0.56);
    border: 1px solid black;
    padding: 5vw 20vw;
    border-radius: 10px;
}

form div {
    display: flex;
    justify-content: space-between;
    width: 100%;
    margin-bottom: .5vw;
}

form div label {
    font-weight: bold;
    font-style: italic;
}

form div input {
    background-color: #868389;
    border: 1px solid black;
    border-radius: 5px;
    padding: 5px;
}

form .button-container{
    justify-content: center;
}

form .button-container button {
    background-color: #868389;
    border: 1px solid black;
    border-radius: 15%;
    padding: 5px;
}

@media only screen and (max-width: 600px) {
    form  {
        padding: 5vw 5vw;
        width: 50vw;
    }

    form div input {
        width: 10vw;
    }
}

HTML ////////////////////////////////////////////////////////////////////////////////

    <section class="form-container">
        <form>
            <div>
                <label for="imie">Imię: </label>
                <input id="imie" placeholder="Imię..." type="text">
            </div>
            <div>
                <label for="nazwisko">Nazwisko: </label>
                <input id="nazwisko" placeholder="Nazwisko..." type="text">
            </div>
            <div class="button-container">
                <button>Wyślij</button>
           </div>
        </form>
    </section>