*{
  box-sizing: border-box;
}

body{
  margin: 0;
}

header{
  margin:0;
}

.system-title{
  background-color: #555555;
  color: white;
  text-align: center;
  padding:10px;
}

.system-img{
  margin: 20px auto;
  width:500px;
  margin-bottom:30px;
}

.system-img img{
  width:100%;
}


.select-area{
  margin: 0 auto;
  padding:30px;
  display: flex;
  flex-direction: column;
  width:600px;
  border-radius: 10px;
  border:5px solid #555555;
}

.select-area select{
  font-size: 20px;
  width:100%;
  margin-bottom:50px;
  text-align: center;
  padding-top: 10px;
  padding-bottom: 10px;
}

#go-btn{
  width:100%;
  text-align: center;
  font-weight: bold;
  font-size: 20px;
}

.btn{
  background-color: rgb(114, 208, 208);
  display: inline-block;
  padding:8px 10px;
  box-shadow:0 5px #00b6b6;
  opacity:0.8;
  border-radius: 15px;
}

.btn:hover{
  cursor:pointer;
  opacity: 1;
}

.btn:active{
  background-color: aqua;
  box-shadow:none;
}