body {
    margin: 0;
    padding: 0;
}

a {
    text-decoration: none;
}

#wrapper {
    width: 100%;
    height: 100vh;
    position: absolute;
    top: 0;
    background: radial-gradient(ellipse at center, rgba(255,255,255,1) 0%,rgba(1,1,1,0.4) 100%);
    background-position: center;
}

.frame {
    width: 50%;
    height: 50%;
    background-color: red;
    float: left;
    overflow: hidden;
    position: relative;
    z-index: 89;
    opacity: 0;
    transition:opacity 2s linear;
    background-position: center;
}

.frame:nth-of-type(1) {
    background-image: url(IMG/HEADER-EVENTI.jpg);
}

.frame:nth-of-type(2) {
    background-image: url(IMG/HEADER-SERVIZI.jpg); 
}

.frame:nth-of-type(3) {
    background-image: url(IMG/HEADER-CONSULENZA.jpg); 
}

.frame:nth-of-type(4) {
    background-image: url(IMG/HEADER-PRODOTTI.jpg); 
}

#freccia_blu {
    margin-top: -30%;
}

.testo {
    color: white;
    margin: 0;
    text-align: center;
    font-style: italic;
    margin-top: 25vh;
    margin-right: 10%;
    margin-left: 10%;
    font-size: 1.5em;
    text-shadow: 2px 2px 2px black;
}

.bottone {
    margin-bottom: 2vh;
    color: white;
    padding-left: 12px;
    padding-right: 12px;
    padding-top: 8px;
    padding-bottom: 6px;
    border-radius: 2px;
    text-shadow: none;
    font-style: normal;
}

#bottone_rosso {
    background: red;
}

#bottone_blu {
    background: blue;
}

#bottone_verde {
    background: green;
}

#bottone_arancione {
    background: orange;
}

#bottone_rosso:hover {
    color: red;
    background: white;
}

#bottone_blu:hover {
    color: blue;
    background: white;
}

#bottone_verde:hover {
    color: green;
    background: white;;
}

#bottone_arancione:hover {
    color: orange;
    background: white;
}

.area_bottone {
    width: 100%;
    text-align: center;
}

#testo_lungo {
    padding-top: 17%;
}

#logo_spazio {
    max-width: 480px;
    position: absolute;
    top: 50%;
    left: 50%;
    margin-top: -240px;
    margin-left: -240px;
}

#logo_spazio img {
    float: left;
    position: relative;
    z-index: 95;
    cursor: pointer;
}

.compari {
    opacity: 1;
}

    #freccia_rossa {
        width: 65.20%;
        height: 34.80%;
    }
    #freccia_arancione {
        width: 34.80%;
        height: 65.20%;
    }
    #freccia_blu {
        width: 34.80%;
        height: 65.20%;
    }
    #freccia_verde {
        width: 65.20%;
        height: 34.80%;
}

#cerchio_bianco {
    width: 300px;
    height: 300px;
    background-image: url("http://www.fabiosartoni.com/wp-content/uploads/2016/05/logo_eventi_e_comunicazione_140.jpg");
    background-repeat: no-repeat;
    background-position: 40% 44%;
    background-color: white;
    border-radius: 50%;
    position: absolute;
    z-index: 94;
    top: 22%;
    left: 22%;
}

/*-- Ottimizzazione testo per il responsive --*/


@media screen and (max-width: 1920px) {
    .frame:first-child p {
        margin-top: 18vh;
    }
    .frame:nth-of-type(2) p {
        margin-top: 18vh;
    }
}

@media screen and (max-width: 556px) {
    .testo {
        font-size: 0;
    }
    .bottone {
        font-size: 18px;
    }
}

@media screen and (max-width: 1450px) {
    .testo {
        font-size: 1.2em;
    }
}

@media screen and (max-height: 820px) {
    .testo {
        font-size: 0;
    }
    .bottone {
        font-size: 18px;
    }
}

@media screen and (min-width: 557px) and (max-width: 820px) {
    .testo {
        font-size: 0;
    }
    .bottone {
        font-size: 22px;
    }
}

/*-- Ottimizzazione logo --*/

@media screen and (max-width: 970px) {
    #logo_spazio {
        max-width: 280px;
        margin-left: -140px;
        margin-top: -140px;
    }
    #cerchio_bianco {
        width: 150px;
        height: 150px;
        background-size: 50%;
        background-position: 54% 53%;
    }
}
    
@media screen and (max-width: 660px) {
    #logo_spazio {
        max-width: 180px;
        margin-left: -90px;
        margin-top: -90px;
    }
    #cerchio_bianco {
        width: 100px;
        height: 100px;
        background-position: 51% 49%;
    }
}

/*-- Ottimizzazione Chrome --*/

@media and (-webkit-min-device-pixel-ratio:0) {
#logo_spazio {
    height: 475px !important;
    }
}

@media screen and (-webkit-min-device-pixel-ratio:0) {
#logo_spazio {
    height: 475px !important;
    }
}

@media and (-webkit-min-device-pixel-ratio:0) and (min-width: 661px) and (max-width: 970px) {
#logo_spazio {
    height: 278px !important;
    }
}

@media screen and (-webkit-min-device-pixel-ratio:0) and (min-width: 661px) and (max-width: 970px) {
#logo_spazio {
    height: 278px !important;
    }
}

@media and (-webkit-min-device-pixel-ratio:0) and (max-width: 660px) {
#logo_spazio {
    height: 177px !important;
    }
}


@media screen and (-webkit-min-device-pixel-ratio:0) and (max-width: 660px) {
#logo_spazio {
    height: 177px !important;
    }
}