#contents {
  width: 1200px;  
}

#thumbnail {
  max-width: 100%;
  width: 800px;
  margin-left: auto;
  margin-right: auto;
  margin-bottom: 60px;
}

#Diagram {
  max-width: 100%;
  width: fit-content;
  margin-left: auto;
  margin-right: auto;
}

#explanation,
#DiagramExplanation,
#UseCase,
#Commentary,
#Policy,
#HowToUse{
    width: calc(100% - 10px);
    margin-left: auto;
    margin-right: auto;
    overflow-wrap: break-word;
}

#userinput {
  margin: 0px 0px 0px 5px;
  width: 250px;
}

h3{
  padding: 0.4em 0.5em;/*文字の上下 左右の余白*/
  color: #494949;/*文字色*/
  background: #f4f4f4;/*背景色*/
  border-left: solid 5px #7db4e6;/*左線*/
  border-bottom: solid 3px #d7d7d7;/*下線*/
}

@media screen and (max-width:1023px) {
  #thumbnail {
      max-width: 100%;
      width: fit-content;
  }
}