* {
  box-sizing: border-box;
}

/* bodyタグ (html全体のレイアウト) */
body {
  margin: 0;
  background-color: #f0f8ff;
  height: 100%;
  font-family: 'Zen Kaku Gothic Antique', sans-serif;
}


/* headerタグ*/
header {
  position: sticky;
  /*headerをページ上部に固定*/
  height: 60px;
  width: 100%;
  padding: 0px 15px;
  background-color: #f1f1f1;
  top: 0;
  z-index: 10;
  display: flex;
}

/* a hover */
a:hover {
  text-decoration: none;
  cursor: pointer;
}

/* title基本 */
.title {
  font-size: calc(17px + 0.7vw);
  position: relative;
  display: inline-block;
  font-weight: bold;
  border-bottom: solid 3px #d5d5d5;
  margin: 0 auto 20px;
  padding: 5px 0 5px 0;
}

.title::after {
  position: absolute;
  content: " ";
  display: block;
  border-bottom: solid 3px #deb887;
  bottom: -3px;
  width: 10%;
}

/* logo */
.logo {
  font-size: 25px;
  position: absolute;
}

/* ナビゲーション */
nav {
  margin: 0 0 0 auto;
  font-family: 'Zen Kaku Gothic Antique', sans-serif;
}

ul {
  display: flex;
  /*横並び*/
  list-style: none;
  padding: 0;
  margin: 0;
}

header a {
  color: #000000;
  text-decoration: none;
  display: block;
  line-height: 60px;
  padding: 0 1.3vw;
  position: relative;
}

.top-nav {
  font-size: calc(0.4vw + 14px);
}

.top-nav::after {
  position: absolute;
  left: 0;
  content: '';
  width: 100%;
  height: 2px;
  background: #000000;
  bottom: -1px;
  transform: scale(0, 1);
  transform-origin: center top;
  transition: transform 0.3s;
}

.top-nav:hover::after {
  transform: scale(1, 1);
}
.announcement {
  text-align: center;
  width: 80%;
  margin: 40px auto 60px;
}
.announcement .students-only{
  margin: 0;
  font-size: calc(12px + 0.25vw);
  color: red;
}

.page {
  text-align: left;
  margin: 15px;
  border-bottom: dotted 3px #000000;
}

.page .time {
  font-size: calc(16px + 0.35vw);
  margin: 0;
}

.page a {
  color: #000000;
}

.page h3 {
  margin: 0 0 20px;
  font-size: calc(18px + 0.2vw)
}
.announcement p{
  margin: 12px;
  font-size: calc(14px + 0.25vw);
}
.back {
  margin: 20px auto 0;
  text-align: left;
}

.back a {
  color: #000;
  font-size: calc(14px + 0.4vw);
  text-decoration: none;
  margin: 20px;
  padding-left: 20px;
}

.dli-chevron-round-left {
  display: inline-block;
  vertical-align: middle;
  color: #333;
  line-height: 1;
  top: -2.5px;
  left: -15px;
  position: relative;
  width: 0.8em;
  height: 0.8em;
  transform: translateX(25%) rotate(-45deg);
}

.dli-chevron-round-left::before,
.dli-chevron-round-left::after {
  content: '';
  position: absolute;
  background: currentColor;
  border-radius: 0.15em;
}

.dli-chevron-round-left::before {
  top: 0;
  left: 0;
  right: 0;
  height: 2.2px;
}

.dli-chevron-round-left::after {
  top: 0;
  left: 0;
  bottom: 0;
  width: 2.2px;
}

.main {
  padding: 10px;
  margin: 40px auto;
  width: 75%;
  height: auto;
  text-align: center;
}

.main .title {
  margin-bottom: 30px;
}

.main .time {
  font-size: 22px;
  margin: 0;
  position: relative;
  text-align: center;
  top: -20px;
}
.main .students-only{
  font-size: 20px;
  margin: 0;
  position: relative;
  text-align: center;
  top: -20px;
  color: red;
}
.text-box h3 {
  font-size: 20px;
  margin: 18px auto 10px;
  padding: 0;
}

.text-box {
  margin: auto;
  padding: 5px 15px;
}

.text-box h4 {
  text-align: left;
  margin: 0;
}

.text-box p {
  margin: 0 auto 30px;
  font-size: calc(13.5px + 0.3vw);
  text-align: left;
}

.text-box .name {
  text-align: right;
}
.iframe-wrapper{
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  overflow: hidden;
}
.iframe-wrapper iframe{
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

footer {
  background-color: #778899;
  width: 100%;
  text-align: center;
  margin: 0 auto;
  padding: 20px;
}

footer .text1 {
  margin: 0 auto;
  padding: 10px 0 5px;
  width: 85%;
}

footer .text2 {
  margin: 0 auto;
  padding: 5px 0;
  width: 85%;
}

footer h4 {
  font-size: 24px;
  margin: 0 auto;
  font-weight: normal;
}

footer p {
  margin: 20px auto 10px;
  padding: 0;
  font-size: 16.5px;
}

footer a {
  color: #000;
}


/* レイアウト崩れるやつ(スマホレイアウト 指定) */
@media screen and (max-width: 490px) {
  .logo {
    font-size: calc(12px + 2.3vw);
  }

  .main {
    width: 90%;
  }

  footer p {
    font-size: 15px;
  }
}