span,
p,
h2,
h3 {
  margin: 0;
  padding: 0;
}
html{
  font-size: 62.5%;
}
* {
  box-sizing: border-box;
}
body {
  font-family:
    -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP",
    "Hiragino Kaku Gothic ProN", "ヒラギノ角ゴ ProN W3", Meiryo, sans-serif;
  text-align: center;
  padding: 6rem;
  background: #ffffff;
  color: #2c3e50;
  display: flex;
  flex-direction: column;
  margin: auto;
  align-items: center;
}

.announcement-box {
  font-size: 1.2em;
  max-width: 700px;
  width: 100%;
  padding: 6rem;
  border: 3px solid #2c3e50;
  background: #ffffff;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
}
.event-title h1{
  font-size: 2.4em;
  font-weight: bold;
  color: #2c3e50;
  margin-bottom: 40px;
  padding-bottom: 20px;
  border-bottom: 2px solid #2c3e50;
  letter-spacing: 0.1em;
}
.main-message {
  font-size: 2.4em;
  font-weight: bold;
  color: #2c3e50;
}
.thank-you-en {
  font-size: 2.2em;
  color: #666;
  margin-bottom: 40px;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Arial, sans-serif;
  font-style: italic;
  letter-spacing: 0.05em;
}
.notice p{
  font-size: 1.2em;
  line-height: 2;
  margin: 30px 0;
  color: #444;
}
.closing-message p{
  font-size: 1.2em;
  margin-top: 40px;
  padding-top: 30px;
  border-top: 1px solid #ddd;
  color: #555;
  line-height: 1.8;
}
.link {
  margin: 20px;
  font-size: 1.2em;
}
.link a {
  text-decoration: underline;
  color: #0000FF;
}
@media screen and (max-width:770px) {
  html {
    font-size: 50%;
  }
  body{
    padding: 1.2rem;
    position:absolute;
    place-self: center;
    inset: 0;
  }
  .main-message {
    font-size: 1.7em;
  }
}