#lecture {
  background-image: url(../image/IMG_2486.jpg);
  background-size: cover;
  background-position: center top;
  background-repeat: no-repeat;
  min-height: 90vh;
}

.main-nav {
  max-width: 1500px;
  display: flex;
  justify-content: flex-end;
  padding: 10px 4%;
  background: white;
  box-shadow: 0 0.5rem 1rem rgba(0, 0, 0, 0.1);
  opacity: 0.9;
}

.main-nav li {
  margin-left: 36px;
  font-size: 20px;
  color: skyblue;
}

/* --------------------------- */

#lecture-detail {
  margin: -50px 40px 0px 40px;
  background: #fafafa;
  padding: 40px 20px 90px 20px;
}

#lecture-detail img {
  width: 450px;
  margin-right: 40px;
}

#lecture-detail .container p {
  padding: 20px 20px 20px 0px;
  font-size: 30px;
}

.detail {
  background: #fff;
  margin-top: -40px;
}

time {
  font-size: 1.2rem;
  position: absolute;
  left: 70%;
  margin-bottom: 20px;
}

.titlebar h2,
h3 {
  position: absolute;
  top: 20px;
  left: 50px;
}

#lecture-detail .titlebar {
  margin-bottom: 0;
}

.lecture-container {
  margin: 40px;
  padding: 40px;
}

@media only screen and (max-width: 660px) {
  #lecture {
    background-image: url(../image/IMG_2486.jpg);
    background-size: cover;
    background-position: top;
    background-repeat: no-repeat;
    min-height: 30vh;
  }

  .titlebar h2 {
    position: absolute;
    top: 20px;
    left: 50px;
  }

  .titlebar {
    margin: 0;
    padding: 10px;
  }

  .main {
    margin: 0 5px;
    padding: 50px 10px;
  }

  .main-nav {
    display: none;
  }

  #lecture-detail {
    margin: -30px 10px 0 10px;
    background: #fafafa;
    padding: 0;
    padding: 40px 0px 90px 0px;
  }

  time {
    margin: 10px 0;
    left: 60%;
  }

  .lecture-container {
    margin: 0px;
    padding: 20px 0;
    margin: 30px;
  }

  .lecture-container p {
    font-size: large;
  }

  .detail {
    background: #fff;
    padding-bottom: 30px;
  }
}

@media screen and (min-width: 481px) and (max-width: 1024px) {
  #lecture {
    background-image: url(../image/IMG_2486.jpg);
    background-size: cover;
    background-position: top;
    background-repeat: no-repeat;
    min-height: 30vh;
  }

  .detail {
    margin-top: -40px;
  }

  .main-nav {
    display: none;
  }

  .main {
    margin: 0;
  }

  .main h2 {
    color: #fafafa;
    font-size: 2.5rem;
    transform: translateY(50%);
  }

  .lecture-container {
    font-size: 1.5rem;
  }

  footer {
    padding: 20px 20px;
    margin: 0 5px;
    position: fixed;
    bottom: 0;
    width: 100%;
  }
}