* {
    margin: 0;
    padding: 0;
    box-sizing: border-box
}
.header_Expo {
    text-align: center;
}
.header_Expo .contenu_header {
    margin: 0 auto;
    padding-top: 15px;
    width: 960px;
    color: #ecf0f1
}
.header_Expo h2 {
    margin-bottom: 10px;
    font-size: 3.5em;
    font-weight: 700;
    line-height: 1em
}
.header_Expo p {
    margin-bottom: 20px
}
.header_Expo a {
    padding: 5px 10px;
    /*display: inline-block;*/
    color: #f1c40f;
    text-decoration: none;
    border: 2px solid #f1c40f;
    border-radius: 6px
}

@media screen and (max-width: 960px) {
    .header_Expo .contenu_header {
        margin: 0;
        width: 100%
    }
}