section#principal {
    background-color: #51626D;
    color: #fff;
    margin-top: -2px;
    background-image: url(../img/education_videos/education_videos_bg@1x.png);
    background-position: 50% bottom;
    background-repeat: no-repeat;
    background-size: 100%;
    background-size: 1400px;
    padding: 70px 0 50px;
}
.container {
    padding-right: 15px;
    padding-left: 15px;
    margin-right: auto;
    margin-left: auto;
}
.header_icon{
    width: 150px;
}
#principal h1 {
    margin: 0;
    color: #fff;
    text-shadow: none;
    text-shadow: 0 1px 10px rgba(0,0,0,0.7);
    margin-top: -20px;
}
#principal p {
    padding-top: 10px;
    font-weight: 300;
    margin: 0 auto;
    display: block;
    text-align: center;
    max-width: 100%;
    text-shadow: 0 1px 10px rgba(0,0,0,0.7);
}
#principal a {
    color: #a7d201;
}
.centrar{
    margin: 0 auto;
}
.video_box{
    max-width: 350px;
    margin:0 auto;
    padding: 0 10px;
}
.video_box a{
    border-radius: 4px;
    position: relative;
    width: 100%;
    display: block;
    background-color: #151D21;
    height: 154px;
    background-repeat: no-repeat;
    overflow: hidden;
    background-size: 300px;
}

.video_box:hover a{
    box-shadow: 0px 1px 10px rgba(0,0,0,0.6);
    opacity: 0.95;
}
.video_box_image{
    position: relative;
}
.video_box_image img{
    width: 79px;
    margin: 50px auto 0;
    display: block;
    border-radius: 12px;
    overflow: hidden;
}

.video_box:hover .video_box_image img{
    box-shadow: 0px 1px 12px rgba(0,0,0,0.9);
}

.video_box h2{
    text-decoration: none;
    font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
    text-shadow: 0 1px 6px rgba(0,0,0,0.9);
    margin-top: 10px;
}
.video_box_content {
    max-width: 350px;
    margin:0 auto 20px;
    padding: 0 10px;
    position: relative;
    display: block;
}
.video_box_content .date {
    font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
    font-size: 1em;
    color: #888;
    padding: 2px 0 4px;
    font-size: 0.8em;
    float: right;
}
.video_name{
    font-size: 18px;
    color: #FFFFFF;
    display: block;
}
.description p{
    font-size: 1em;
    color: #383838;
    margin-bottom: 30px;
    text-align: justify;
    padding: 0 0px;
    line-height: 1.4em;
}


.introduction a{
    background-image: url(../img/education_videos/introduction@1x.png);
}
.sources a{
    background-image: url(../img/education_videos/sources@1x.png);
}
.datasets a{
    background-image: url(../img/education_videos/datasets@1x.png);
}
.models1 a{
    background-image: url(../img/education_videos/models1@1x.png);
}
.models2 a{
    background-image: url(../img/education_videos/models2@1x.png);
}
.ensembles a{
    background-image: url(../img/education_videos/ensembles@1x.png);
}
.logisticregression a{
    background-image: url(../img/education_videos/logistic_regression@1x.png);
}
.predictions a{
    background-image: url(../img/education_videos/predictions@1x.png);
}
.supervisedvsunsupervised a{
    background-image: url(../img/education_videos/supervisedvsunsupervised@1x.png);
}
.clustering a{
    background-image: url(../img/education_videos/clustering@1x.png);
}
.association a{
    background-image: url(../img/education_videos/association@1x.png);
}
.anomalydetection a{
    background-image: url(../img/education_videos/anomalydetection@1x.png);
}
.topicmodels a{
    background-image: url(../img/education_videos/topicmodels@1x.png);
}
.timeseries a{
    background-image: url(../img/education_videos/timeseries@1x.png);
}
.flatline a{
    background-image: url(../img/education_videos/flatline@1x.png);
}
.evaluations a{
    background-image: url(../img/education_videos/evaluations.png);
}
.deepnets a{
    background-image: url(../img/education_videos/deepnets.png);
}
.organizations a{
    background-image: url(../img/education_videos/organizations.png);
}
.optiml a{
    background-image: url(../img/education_videos/optiml.png);
}


.video_box_image span{
    height: 30px;
    width: 30px;
    display: block;
    font-size:19px;
    border-radius: 50%;
    background: rgba(255,255,255,0.30);
    font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
    font-weight: 600;
    color: #151D21;
    position: absolute;
    right: 14px;
    top: 14px;
    padding: 5px 4px;
}

.video_box_image:hover span{
    background: rgba(255,255,255,0.80);
}
.video_box_content span{
    padding: 5px 18px 5px 20px;
    margin-bottom: 10px;
    margin-top: 5px;
}
.see_slide{
    padding-top: 2px;
}
.see_slide a{
    width: 26px;
    height: 20px;
    background-size: 24px;
    background-image: url(../img/certifications/icon_cer_resource_slides.png);
    display: block;
    vertical-align: middle;
    background-repeat: no-repeat;
    float: left;
    margin: 3px 8px 0 0;
}

a.hash.icon {
    vertical-align: middle;
    background: none;
    display: block;
}
a.hash .icon-link {
    background: url(../img/icon_link.png) no-repeat scroll left 47% rgba(0,0,0,0);
    height: 20px;
    width: 26px;
    background-size: 24px;
    display: block;
    margin-top: 0;
}
a.youku{
    background: url(../img/documentation/youku_logo.png) no-repeat scroll left 47% rgba(0,0,0,0) !important;
    height: 22px;
    width: 30px;
    background-size: 22px !important;
    display: block;
    margin-top: 2px;
    border-right: 1px solid #ddd;
}
@media screen and (max-width: 768px){
    section#principal {
        background-size: 200%;
        padding: 40px 0 40px;
    }
    .header_icon{
        width: 120px;
    }
    #principal h1 {
        margin-top: -10px;
        font-size: 1.5em;
    }
    #principal p {
        font-size: 0.78em;
        line-height: 1.35em;
        text-align: justify;
        max-width: 95%;
    }
    .description p {
        font-size: 1em;
        color: #383838;
        margin-bottom: 35px;
        text-align: justify;
        padding: 0 0px;
        line-height: 1.35em;
    }
}
@media
(-webkit-min-device-pixel-ratio: 2),
(min-resolution: 192dpi) {
    .introduction a{
        background-image: url(../img/education_videos/introduction@2x.png);
    }
    .sources a{
        background-image: url(../img/education_videos/sources@2x.png);
    }
    .datasets a{
        background-image: url(../img/education_videos/datasets@2x.png);
    }
    .models1 a{
        background-image: url(../img/education_videos/models1@2x.png);
    }
    .models2 a{
        background-image: url(../img/education_videos/models2@2x.png);
    }
    .ensembles a{
        background-image: url(../img/education_videos/ensembles@2x.png);
    }
    .logisticregression a{
        background-image: url(../img/education_videos/logistic_regression@2x.png);
    }
    .predictions a{
        background-image: url(../img/education_videos/predictions@2x.png);
    }
    .supervisedvsunsupervised a{
        background-image: url(../img/education_videos/supervisedvsunsupervised@2x.png);
    }
    .clustering a{
        background-image: url(../img/education_videos/clustering@2x.png);
    }
    .association a{
        background-image: url(../img/education_videos/association@2x.png);
    }
    .anomalydetection a{
        background-image: url(../img/education_videos/anomalydetection@2x.png);
    }
    .topicmodels a{
        background-image: url(../img/education_videos/topicmodels@2x.png);
    }
    .timeseries a{
        background-image: url(../img/education_videos/timeseries@2x.png);
    }
    .flatline a{
        background-image: url(../img/education_videos/flatline@2x.png);
    }
    .evaluations a{
        background-image: url(../img/education_videos/evaluations.png);
    }
    .deepnets a{
        background-image: url(../img/education_videos/deepnets@2x.png);
    }
    .section#principal {
        background-image: url(../img/education_videos/education_videos_bg@2x.png);
    }
    .see_slide a{
        background-image: url(../img/certifications/icon_cer_resource_slides@2x.png);
    }
    .organizations a{
        background-image: url(../img/education_videos/organizations@2x.png);
    }
    .optiml a{
        background-image: url(../img/education_videos/optiml@2x.png);
    }
}