body {
    font-family: Arial, Helvetica, sans-serif;
    position: relative;
    display: block;
}

.header {
    margin-top: 3rem;
    margin-bottom: 3rem;
}

.header img {
    width: 100%;
    max-width: 100px;
    height: auto;
}

.logo {
    width: 100%;
    max-width: 350px;
    text-align: center;
}

.logo img {
    width: 100%;
    height: auto;
}

.text-center {
    text-align: center;
}

.os-list {
    display: flex;
    gap: 3rem;
    max-width: 980px;
    width: 100%;
    margin: 2rem auto;
}

.os-entry {
    padding: 1rem;
    width: 25%;
    border: 1px solid #ccc;
}

.os-entry:hover  {
    background-color: #104070;
    color: #fff;
}

.os-entry:hover a, .os-entry:hover h4 {
color: #fff;
}

.os-list h4 {
    font-size: 2rem;
    font-weight: bold;
}

.os-list a {
    text-decoration: none;
}

.footer {
    position: relative;
    bottom: -50px;
    width: 300px;
    margin: 0 auto;
    padding-bottom: 2rem;
}

.os-entry img {
    width: 100px;
    height: 100px;
}

@media (max-width:480px) {
    .os-list {
        display: block;
        padding-left: 1rem;
        padding-right: 1rem;
        width: 320px;
    }

    .os-entry {
        width: auto;
        margin-bottom: 2rem;
    }
}