.logo {
    max-width:80px
}
.nav-link {
    color : #fffff !important;
    font-size: 16pt !important;
}
.main {
     width: 100vw;
     height: calc(100vh );
     /*background: url('../images/main.png');
     background-size:cover;
     background-repeat:no-repeat;
     filter: brightness(80%);
     background-attachment: fixed;*/
}
.fullscreen-bg {
    overflow: hidden;
    z-index: -100;
    position: relative;
    height: 100%;
    width: 100%;
    padding-top:45%;
}

.fullscreen-bg__video {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
}
.overlay {
    background: rgba(0,0,0,0.6);
    position: absolute;
    top:0;
    left:0;
    width: 100%;
    height: 100%;
    z-index: 4;
}
.overlay h1 {
    text-align:center;
    color:#fff;
    font-size: 70px;
    margin-top:17%;
}


.logo {
    max-width: 40px;
}
.nav-link {
    color: #ffffff !important;
    font-size: 16pt !important;
}
.main {
    width: 100vw;
    height: calc(100vh);
    background: url('../images/main_back.png');
    background-size: cover;
    background-repeat: no-repeat;

    background-attachment: fixed;
}
#study {
    background-color: #404040;
}
.min {
    width: 250px;
    height: 250px;
    background-color: #404040;
    display: inline-block;
    transition: 1s;
}
.max {
    width: 500px;
    height: 500px;
    background-color: #404040;
    display: inline-block;
    transition: 1s;
}
.btn-menu {
    padding-top: 5rem;
}
.fnt-btn {
    font-size: 24pt;
}
#btn1 {
    position : absolute;
    left: 10px;
}
#btn2 {
    position : absolute;
    left: 270px;
}
#btn3 {
    position : absolute;
    left: 780px;
}