header, section, footer {
    width: 1200px;
    margin-left: auto;
    margin-right: auto;
    font-family: 'Trebuchet MS', 'Lucida Sans Unicode', 'Lucida Grande', 'Lucida Sans', Arial, sans-serif;
}
header {
    height: 200px;
    background-color: rgb(19, 18, 18);
}
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
nav {
    width: 500px;
    margin-right: 10px;
    margin-top: 90px;
    font-size: 30px;
    float: right;
    text-align: center;
}
.menu-horizontal {
    list-style-type: none;
    display: flex;
    justify-content: space-around;
}
.menu-horizontal > li > a {
    display: block;
    padding: 15px 20px;
    color: darkorange;
    text-decoration: none;
}
.menu-horizontal > li > a:hover {
    background-color: rgb(90, 89, 89);
}
.menu-vertical {
    position: relative;
    display: none;
    list-style: none;
    width: 190px;
    text-align: center;
    background-color:rgb(19, 18, 18)
}
.menu-horizontal > li:hover .menu-vertical {
    display: block;
}
.menu-vertical li :hover {
    background-color: rgb(90, 89, 89);
}
.menu-vertical li a {
    display: block;
    color: darkorange;
    padding: 15px 15px 15px 20px;
    text-decoration: none;
}
#h_b2 {
    height: 180px;
    width: 440px;
    float: left;
    background-image: url(imagenes/logo-imagen.gif);
    background-size: cover;
    margin-left: 40px;
    margin-top: 10px;
}
section {
    height: 1100px;
    background-color: rgb(19, 18, 18);
    padding-top: 20px;
}
#s_b1 {
    height: 600px;
    width: 500px;
    padding-top: 180px;
    margin-left: 380px;
    position: absolute;
}
p {
    text-align: center;
    margin-left: 10px;
    padding-bottom: 5px;
    color: rgb(243, 101, 6);
    font-size: 30px;
    font-weight: bold;
}
footer {
    height: 150px;
    background-color: rgb(19, 18, 18);
}
#f_b1 {
    height: 90px;
    width: 300px;
    float: left;
    margin-top: 25px;
    margin-left: 10px;
}
#f_b2 {
    height: 90px;
    width: 300px;
    float: left;
    margin-top: 25px;
    margin-left: 60px;
}
#f_b3 {
    height: 90px;
    width: 300px;
    float: right;
    margin-top: 25px;
    margin-right: 60px;
}
.letras {
    color: darkorange;
    font-size: 20px;
    font-weight: 50px;
    text-align: center;
    padding: 5px;
}
h2 {
    text-align: center;
    color: white;
}

@media all and (max-width: 570px) {
    header, section, footer {
        width: 100%;
    }
    header {
        height: auto;
    }
    nav {
        width: 100%;
        margin-right: 0;
        margin-top: 0;
        font-size: 20px;
        float: none;
    }
    .menu-vertical {
        width: 100%;
    }
    section {
        height: 650px;
        background-color: rgb(19, 18, 18);
        background-image: none;
    }
    #h_b2 {
        width: 100%;
        float: none;
        margin-left: 0;
        margin-top: 0;
    }
    p {
        color: darkorange;
        text-align: left;
        font-size: 25px;
    }
    #s_b1 {
        height: auto;
        width: 100%;
        padding-top: 10px;
        margin-left: 0;
        position: absolute;
    }
    footer {
        height: auto;
    }
    #f_b1 {
        height: auto;
        width: 100%;
        float: none;
        margin-top: 0;
        margin-left: 0;
    }
    #f_b2 {
        height: auto;
        width: 100%;
        float: none;
        margin-top: 0;
        margin-left: 0;
    }
    #f_b3 {
        height: auto;
        width: 100%;
        float: none;
        margin-top: 0;
        margin-right: 0;
    }  
}