div#theatre {
    width: 100vw;
    height: 100vh;
    font-size: max(16px,min(24px,3vw));
    position: absolute;
    color: rgba(255,255,255, 0.3);
    text-shadow: 0 0 2px yellow , 0 0 4px black,0 0 6px white;
}

@-moz-document url-prefix() {
    div#theatre {
        text-shadow: 0 0 1px yellow , 0 0 3px black,0 0 9px white;
    }
}

/* For backwards compatibility 
---------------------------------------*/
@media screen and (min-width: 800px) {
    div#theatre {
        font-size: 24px;
    }
}

@media screen and (max-width: 800px) and (min-width: 550px) {
    div#theatre {
        font-size: 3vw;
    }
}

@media screen and (max-width: 550px) {
    div#theatre {
        font-size: 16px;
    }
}
/*---------------------------------------*/

div#theatre #background-img {
    width: 100%;
    height: 100%;
    position: fixed;
    z-index: 100;
    background-size: cover;
    filter: brightness(20%);

    /* To avoid flickering brightness transition */
    -webkit-transform-style: preserve-3d;
    -webkit-backface-visibility: hidden;
    transform-style: preserve-3d;
    backface-visibility: hidden;
    /* ----------------------------- */
}

div#theatre #history {
    position: relative;
    z-index: 200;
    text-align: left;
    text-shadow: 0 0 1px #12ff00, 0 0 3px black, 0 0 4px black;
}

div#theatre #curtain-left, div#theatre #curtain-right {
    content: '';
    position: absolute;
    z-index: 300;
    top: -30px;
    bottom: -30px;
    width: 61%;
    transition: all 4s ease-out;
    transform: rotate(0deg);
    background-color: #A90505;
    background-image: linear-gradient(90deg,  transparent 10%, rgba(255,255,255,.25) 50% ,transparent 65% );
    background-repeat: repeat;
    box-shadow: 0 0 10px #555 ,inset 0 -60px  60px -30px  rgba(255,255,255, 0.5), inset 0 90px  60px -30px  rgba(0,0,0, 0.5);
    background-size: 80px;
}

#curtain-left { left: -10% }

#curtain-right { right: -10% }

#theatre.open #curtain-left {
    transform: rotate(15deg);
}

#theatre.open #curtain-right {
    transform: rotate(-15deg);
}

#theatre.open #curtain-left, #theatre.open #curtain-right {
    width: 0;
    background-size: 1px;
    transition: all 4s ease;
}

#theatre.open #background-img {
    filter: brightness(100%);
    transition: all 4s ease;
}