body {
  margin: 0;
}

.loader {
  position: fixed;
  width: 100%;
  height: 100vh;
  background-color: #000;
  z-index: 555;
  top: 0;
  left: 0;
  text-align: center;
  padding: 30px;
}

.loader .txt {
  font-size: 40px;
  font-weight: bold;
  margin-bottom: 30px;
  color: #fff;
  font-family: "Noto Sans JP";
}

.page_title {
  background: #000;
  color: white;
  padding: 5px;
  margin: 0px;
  font-weight: bold;
}

.contents {
  max-width: 1500px;
  margin: 0 auto;
  display: flex;
}

pre {
  font-size: 16px;
}

#nav {
  width: 230px;
  background-color: #008080;
  position: fixed;
  overflow: scroll;
  height: 100vh;
}

#nav ul li {
  color: #fff;
  line-height: 2;
  padding: 10px;
  border-bottom: solid;
}

#nav ul li:hover {
  cursor: pointer;
  background: #8fbc8f;
}

#main_contents {
  width: calc(100% - 230px);
  background-color: #f8f8ff;
  padding: 15px;
  margin-left: 230px;
  height: 500vh;
}

.answer_code {
  width: auto;
  background: #fff;
  padding: 10px;
  margin-top: 30px;
  border: solid 2px #008080;
}

.answer_code .answer_code_inner {
  width: auto;
  border: none;
  background: #f0f8ff;
  padding: 5px;
}

.answer_code .answer_code_inner span {
  color: #4169e1;
  font-size: 14px;
  font-weight: bold;
}