body {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Open Sans', sans-serif;
}

.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border: 1px solid red;
}

.logo {
    margin-left: 3rem;
}

.logo-img {
    width: 9.375rem;
}

.btn {
    padding: 0.6rem 2.81rem;
    margin: 1.5rem 1.25rem;
    border-radius: 1.5rem;
    border: none;
    background-color: #fff;
    box-shadow: 2px 1px 5px 0px #808080;
    cursor: pointer;
}

/* for Mobile  */

@media only screen and (max-width:400px) {

    .logo {
        margin-left: 1rem;
    }

    .logo-img {
        width: 6.375rem;
    }

    .btn {
        padding: 0.4rem 1rem;
        margin: 1.5rem 1.25rem;
    }
}