body {
    margin: 0;
    padding: 0;
    font-size: 0.8125rem;
    font-weight: normal;
    line-height: 1.5;
    height: 100vh;
    background-color: #efefef;
}

h1, p, a {
    font-family: sans-serif;
}

.center {
    text-align: center;
}

.container {
    margin: 0 auto;
    padding: 0;
}

.responsive-image {
    max-width: 100%;
}

.thumbnails {
    padding: 0 1rem;
    display: flex;
    flex-wrap: wrap;
    flex-direction: row;
}

.thumb {
    width: calc(25% - 2rem);
    margin: 1rem;
    cursor: pointer;
}

.thumb img {
    display: block;
    /* border: 1px solid gray; */
}

.pages, .thumbnails {
    display: none;
}

.page {
    display: hidden;
    margin: 0;
    width: 100vw;
    height: 100vh;
    cursor: pointer;
    background-repeat: no-repeat;
    background-position: center center;
    background-attachment: fixed;
    -webkit-background-size: contain;
    -moz-background-size: contain;
    -o-background-size: contain;
    background-size: contain;
}

#btn-previous, #btn-next, #btn-thumbnails, #btn-zoom-in, #btn-zoom-out {
    background-color: rgba(0, 0, 0, 0.3);
    background-repeat: no-repeat;
    cursor: pointer;
    width: 40px;
    height: 50px;
    z-index: 1000;
    background-position-y: center;
    position: fixed;
    background-size: 30px 30px;
    border-radius: 5px;
    bottom: 10px;
}

#btn-thumbnails {
    margin-top: 0px;
    bottom: 70px;
    background-position: 50% 50%;
    right: 10px;
    background-size: 55px 55px;
}

#btn-previous {
    background-position: 35% 50%;
    left: 10px;
}

#btn-next {
    background-position: 65% 50%;
    right: 10px;
}

#btn-zoom-in {
    background-position: 60% 50%;
    left: 15px;
    top: 50px;
    height: 40px;
}

#btn-zoom-out {
    background-position: 60% 50%;
    left: 15px;
    top: 100px;
    height: 40px;
}

.shimmer {
    color: grey;
    display: inline-block;
    mask: linear-gradient(-30deg,#000 30%,#0005,#000 70%) right/300% 200%;
    -webkit-mask: linear-gradient(-30deg,#000 30%,#0005,#000 70%) right/300% 200%;
    background-repeat: no-repeat;
    animation: shimmer 2.5s infinite;
    background-size:contain;
    background-repeat:no-repeat;
    background-position:center;
    animation-timing-function: linear;
}

@-webkit-keyframes shimmer {
    100% { -webkit-mask-position:left }
}

@keyframes shimmer {
    100% { mask-position:left }
}