html,
body {
    margin: 0;
    padding: 0;
    font-family: Arial, sans-serif;
    font-size: 20px;
    line-height: 30px;
}

body {
    background-color: #051a4d;
    color: #ddd;
}

body.content {
    background-color: #eee;
    width: 100%;
}

.flex {
    padding: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.flex>div {
    width: 50%;
}

h1 {
    line-height: 42px;
}
.br {
    border-right: 1px solid #ddd;
}

.flex>div:first-child {
    padding-right: 50px;
}

.pl-50 {
    padding-left: 50px;
}

.button {
    display: inline-block;
    padding: 10px 20px;
    background-color: #53bafc;
    color: #fff;
    text-decoration: none;
    border-radius: 5px;
    margin-top: 20px;
}

footer {
    width: 500px;
    margin: 75px auto;
    text-align: center;
}

footer img {
    height: 50px;
}

footer ul {
    display: flex;
    gap: 25px;
    list-style: none;
    padding: 0;
    margin: 0;
    justify-content: center;
    font-size: 10px;
}

footer a {
    color: #ddd;
    text-decoration: none;
}
footer.content a {
    color: #333;
}

header {
    background-color: #051a4d;

}
.main {
    padding: 50px;
    color: #333;
}

.topic  {
    width: 75%;
    margin: 50px auto;

}

@media screen and (max-width: 720px) {
    .flex {
        flex-direction: column;
        padding: 25px;
    }
    .flex-rev {
        flex-direction: column-reverse;
    }
    .flex>div {
        width: 100%;
    }
    .flex>div:first-child {
        padding-right: 0;
    }
    .pl-50 {
        padding-left: 0;
    }   

    header img {
        width: 100%;
    }
    .main {
        padding: 20px;
        font-size: 18px;
    }
    .main h1 {
        
        font-size: 28px;
        line-height: 36px;
    }
    .topic {
        padding: 0;
        width: inherit;
    }

    .topic img {
        width: 100%;
    }
    .w-400 {
        width: 100%;
    }
    footer {
        width: 100%;
    }
    .content {
        font-size: 18px;
    }
    .logo {
        width: 100%;
    }
    .content h1 {
        font-size: 26px;
    }
}