html, body {
  font-family: Verdana,sans-serif;
  font-size: 15px;
  line-height: 1.5;
}
#content {
  margin: auto;
  width: 800px;
  padding: 10px;
  
/*   https://www.cssmatic.com/box-shadow */
-webkit-box-shadow: -7px 7px 19px 2px rgba(0,0,0,0.3);
-moz-box-shadow: -7px 7px 19px 2px rgba(0,0,0,0.3);
box-shadow: -7px 7px 19px 2px rgba(0,0,0,0.3);
  
/*   https://www.cssmatic.com/border-radius */
  border-radius: 10px 10px 10px 10px;
-moz-border-radius: 10px 10px 10px 10px;
-webkit-border-radius: 10px 10px 10px 10px;
border: 0px solid #000000;
}
.slide {
  text-align: left;
  display: inline-block;
  width: 800px;
}
li {
  margin-bottom: 10px
}
.dalej, #brakdanych {
  float: right;
}
.overflow {
  height: 200px;
}
body {
/*   https://stackoverflow.com/questions/826782/how-to-disable-text-selection-highlighting */
    -webkit-touch-callout: none; /* iOS Safari */
    -webkit-user-select: none;   /* Safari */
    -khtml-user-select: none;    /* Konqueror HTML */
    -moz-user-select: none;      /* Firefox */
    -ms-user-select: none;       /* Internet Explorer/Edge */
    user-select: none;           /* Non-prefixed version, currently supported by Chrome and Opera */
}
img {
/*   https://stackoverflow.com/questions/7439042/css-js-to-prevent-dragging-of-ghost-image */
  -webkit-user-drag: none;
  -khtml-user-drag: none;
  -moz-user-drag: none;
  -o-user-drag: none;
  user-drag: none;
}
.pic {
  position: relative;
  display: inline-block;
  overflow: hidden;
}
.diff {
  position: absolute;
/*   border: 1px solid; */
  border-radius: 10px 10px 10px 10px;
  -moz-border-radius: 10px 10px 10px 10px;
  -webkit-border-radius: 10px 10px 10px 10px;
}
.diff.done{
  border: 5px ridge red;
/*   border: 2px;
  border-style: dotted; */
}
.missclick {
  position: absolute;
  width: 100%;
  height: 100%;
  left: 0px;
  top: 0px;
  background-color: #ffffff;
  opacity: .9;
  display: none;
  text-align: center;
  overflow: auto;
  vertical-align: middle;
  font-size: 40px;
  padding-top: 20%;
}