header {
  width: 100%;
  border: solid #627D98;
  /*position: fixed;*/
}

.nav {
  /*background-color: #D9E2EC;*/
  padding: 0px;
  display: flex;
  height: 50px;

}

.title {
  padding-left: 40px;
  margin-top: 12px;
}

h1 {
  font-size: 16px;
  padding: 0;
  margin: 0;
}

.nav-child {
  display: flex;
  padding-left: 240px;

}

.nav-grandchild {
  padding-left: 100px;
  margin-top: 12px;
}

.nav-grandchild a {
  color: #627D98;
}

/*
.hamburger{
  display: none;
}
  */
@media screen and (min-width: 1200px) {
  .off-screen-menu {
    display: none;
  }

  a {
    text-decoration: none;
    /*color: #627D98;*/
  }

  body {
    margin: 0px;
    height: 100%;
    
  }

  hr {
    margin: 0px;
  }

  main {
    height: 1600px;
    border: solid #627D98;
  }

  .main-first {
    height: 600px;
    border: solid #627D98;

  }
}

/* ↓ watching Youtube */
@media screen and (max-width: 1200px) {
  .off-screen-menu a {
    color: azure;
  }

  .off-screen-menu li {
    list-style: none;
    padding-left: 0;
  }

  .nav-child {
    display: none;
  }

  .off-screen-menu {
    background-color: rgb(34, 37, 49);
    height: 100vh;
    width: 100%;
    max-width: 450px;
    position: fixed;
    top: 0;
    right: -450px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    font-size: 3rem;
    transition: .3s ease;
  }

  .off-screen-menu.active {
    right: 0;
  }

  .hamburger {
    height: 50px;
    width: 50px;
    margin-left: auto;
    position: relative;
  }

  .hamburger span {
    height: 5px;
    width: 100%;
    background-color: #6F86FF;
    border-radius: 25px;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    transition: .3s ease;
  }

  .hamburger span:nth-child(1) {
    top: 25%;
  }

  .hamburger span:nth-child(3) {
    top: 75%;
  }

  .hamburger.active span:nth-child(1) {
    top: 50%;
    transform: translate(-50%, -50%) rotate(45deg);
  }

  .hamburger.active span:nth-child(2) {
    opacity: 0;
  }

  .hamburger.active span:nth-child(3) {
    top: 50%;
    transform: translate(-50%, -50%) rotate(-45deg);
  }
}