html, body{
  width: 100%;
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Helvetica Neue", "Noto Sans Japanese", "ヒラギノ角ゴ ProN W3", Hiragino Kaku Gothic ProN, Arial, Meiryo, sans-serif;
}
*{
  box-sizing: border-box;
}
#header{
  background-color: #50505e;
  height: 100px;
  float: top;
}
.header-inner{
  width: 94%;
  margin: 0 3%;
  float: top;
  height: 100%;
}

a {
  text-decoration: none;
  color: inherit;
}

@media screen and (max-width: 600px){
  header img{
    display: none;
  }
  .header-inner{
    width: 100%;
    margin: 0;
    hight: 20%;
  }
 .header-title{
    font-size: 24px;
/*    margin-top:00px;*/
    width: 90%;
    margin: -20 20px;
  }
 .discription-text{
    font-size: 30px;
  }
  .lesson-content{
    float: top;
    width: 90%;
    margin: 10px 5%;
  }
  .copyright{
    padding: 40px 10px;
  }
}

@media (max-width: 768px) {
  .row {

  }
}

@media (min-width: 768px) {
  .row {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
  }
}

.header-title{
/*  width: 310px; */
  padding: 32px;
  padding-top: 40px;
  padding-bottom: 5px;
  font-size: 28px;
  font-family: 'Avenir Next';
  color: #fff;
  float: left;
}
#header img{
  height: 100px;
  float: left;
  opacity: 0.7;
}
.discription{
  background-image: url('../pics/grund-data-bg.jpg');
  background-size: cover;
  background-repeat: no-repeat;
  overflow: auto;
  padding: 0 50px;
  font-family: 'Avenir Next';
  float: top;
}
.discription-text{
  font-weight: bolder;
  font-size: 45px;
  line-height: 45px;
  margin: 0 30px;
  padding-top: 35px;
  opacity: 0.6;
}
.row {
  width:100%;
  float:left;
}
.lesson-content{
  height: auto;
  overflow: auto;
  width: 90%;
  margin: 35px 3%;
  background-color: white;
  box-shadow: 10px 10px 10px 5px rgba(0, 0, 0, 0.3);
  float: left;
}
.lesson-content:hover{
  opacity: 0.7;
  transition: 300ms ease;
}

.lesson-content-title{
  margin: 5px 30px;
  font-size: 20px;
  font-weight: bold;
}
.lesson-content-img{
  margin: 0 auto;
  margin-top: 30px;
  width: 80%;
  height: 120px;
  padding-bottom: 35px;
  border-bottom: 1px solid;
}
.lesson-content-img img{
  display: block;
  margin: auto;
  max-height: 100%;
}
.lesson-content-level-wrap{
  height: 15px;
  width:  100%;
  padding:  0 25px;
  font-size: 10px;
}
.content-level{
  background-color: #EEE;
  width: 23%;
  text-align: center;
  font-weight: bold;
  margin: 1px 1%;
  float: left;
  border-radius: 2px;
}
.level-a1{background-color: #69b;}
.level-a2{background-color: #69b;}
.level-b1{background-color: #fc7;}
.level-b2{background-color: #eb7;}
.level-c1{background-color: #F77;}
.level-c2{background-color: #d77;}

.lesson-content-description{
  padding: 10px 30px;
  font-size: 13px;
  float: left;
}
footer{
  height: 150px;
  background-color: #50505e;
  width: 100%;
  color: #bbc;
  font-family: 'Avenir Next';
}
.copyright{
  padding: 30px 30%;
  font-weight: lighter;
  font-size: 13px;
}