*{
    box-sizing: border-box;
    font-family: Arial, Helvetica, sans-serif;
    margin: 0;
    padding: 0;
}
header {
    background-color: rgb(60, 78, 114);
    height: 70px;
    width: 100%;
}
.menu-icon{display: none;}
#check{display: none;}
.menu{
    float: right;
    margin: 0 10px 0 0;
    top: 25px;
    right: 100px;
    position: absolute;
}
.menu a{
    color: #fff;
    text-decoration: none;
    font-size: 14px;
    margin-right: 30px;
}
.marca {
    color: #fff;
    font-size: 20px;
    display: block;
    position: absolute;
    top: 22px;
    left: 100px;
}
.imagen{
    display: flex;
    padding: 10px;
    justify-content: center;
}
.tema{
    margin: 20px 0 0 0;
    font-size: 22px;
    font-weight: bold;
}
.division{
    border-top: 1px solid #c0c0c0;
    height: 1px;
    padding: 0;
    margin: 20px 0;
    width: 100%;
}
.imagen img{
    height: 340px;
    width: 700px;
}
.contenido{
    display: flex;
    margin: auto;
    flex-wrap: wrap;
    position: relative;
    justify-content: center;
    align-items: center;
    width: 46%;
}
.contenido h1, h2{
    font-size: 20px;
    margin: 20px 0;
}
@media screen  and (max-width: 640px){
    .marca{left: 34%;}
    .imagen img{width: 400px;}
    .contenido{width: 95%;}
}
@media screen and (max-width: 800px) {
    #check:checked ~ .menu{left: 0;}      
    .menu{
        background: #fff;
        top: 69px;
        left: -100%;
        transition: all 0.8s ease;
        overflow-y: scroll;
        overflow: -moz-scrollbars-vertical;
        width: 100%;
        height: 100vh;
        z-index: 200;
    }
    .menu a{
        color: #000;
        display: block;
        border-bottom: 1px solid #000;
        box-sizing: border-box;
        text-transform: uppercase;
        font-size: 0.8rem;
        padding: 2px 0 0 0;
        padding-left: 30px;
        line-height: 65px;
        height: 70px;
        width: 100%;
    } 
    .menu-icon{
        cursor: pointer;
        display: block;
        float: left;
        left: 5%;
        margin: 20px 5px; 
        position: absolute;
    }
}