* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

#app {
  margin: 20px;
  text-align: center;
}
.head{
  text-align: left;
  font-size:20px;
  position: relative;
  width: 600px;
  margin: 0 auto;
  line-height: 1;
}
.head h1{
  display: inline;
  font-size: 20px;
}
.head p{
  display: inline;
  font-size: 16px;
  padding-left: 10px;
}
.head p span{
  padding: 0 5px;
  cursor: pointer;
  color: #19aaff;
  font-size: 16px;
}
.head .renovate{
  color: #d70000;
  font-weight: normal;
  position: absolute;
  right: 0;
  bottom:0;
  font-size: 16px;
  cursor: pointer;
}

.box {
  border: 2px solid #000;
  min-height: 200px;
  min-width: 600px;
  border-style: dashed;
  text-align: center;
  padding:20px;
  position: relative;
  z-index: 1;
  display: table;
  margin: 20px auto 0;
}
.box b{
  position: absolute;
  z-index: 1;
  top:0;
  left:0;
  right:0;
  text-align: center;
  line-height: 200px;
  font-weight: normal;
  color: #999;
}

.box .img {
  position: relative;
  display: table;
  margin: 0 auto;
  z-index: 2;
}

.box .img img {
  display: block;
}

.watermark {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 2;
  background: url(./watermark.png) center/ 20% auto;
  opacity: 0.2;
}