body {
  font-family: "Helvetica Neue", "メイリオ", "Arial", "Meiryo", "Hiragino kaku Gothic Pro", "ヒラギノ角ゴ Pro", sans-serif;
}

.header{
  background-color:black;
}

.header a{
  color: white;
}

.footer a{
  color: white;
}
.main {
  display:flex;
}
.menu{
  flex: 0;
  margin-right: 30px;
}
.mcolor{
    background-color: ;
}
.mcontents{
  flex: 1;
  margin-right:0;
  color: black;
}
.menu2{
  flex: 0.5;
  margin-right:30px;
}
a:hover {
   opacity: 0.75;
}
a {text-decoration: none}

a {color: black;}

h1{
  font-size:150%;
  color: #000000;
  background-color: #696969;
}
h2{
  font-size:130%;
  color: #000000;
  background-color: #d3d3d3;
}
.box {
  width: 780px;
  height: 300px;
  overflow-y: scroll;
}
.footer {
  background-color: black;
  color: white;
  padding-bottom: 10px;
}
.area {
  width: 500px;
  margin: auto;
  flex-wrap: wrap;
  display: flex;
}
 
.tab_class {
  width: calc(100%/5);
  height: 50px;
  background-color: black;
  color: white;
  line-height: 50px;
  font-size: 15px;
  text-align: center;
  display: block;
  float: left;
  order: -1;
}
 
input[name="tab_name"] {
  display: none;
}
 
input:checked + .tab_class {
  background-color: forestgreen;
  color: white;
}
 
.content_class {
  display: none;
  width: 100%;
}
 
input:checked + .tab_class + .content_class {
  display: block;
}