body {
  font-family: "Yu Gothic", "游ゴシック", sans-serif;
  margin: 0;
  background-color: #fff;
  color: #333;
  overflow-x: hidden;
  font-family: "游ゴシック体", YuGothic, "游ゴシック Medium", "Yu Gothic Medium", "游ゴシック", "Yu Gothic", sans-serif;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 20px;
}

.logo {
  text-align: center;
  margin: 5em auto 2em;
}

.logo img {
  max-width: 100%;
  height: auto;
}

.responsive-logo {
  width: 30%;
  height: auto;
  display: block;
  margin: 0 auto;
}

h1.title {
  font-size: 32px;
  color: #000;
  position: relative;
  display: inline-block;
  margin-top: 2em;
  margin-bottom: 1em;
}

h1.title::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -6px;
  width: 100%;
  height: 2px;
  background: linear-gradient(to right, #35c5f3, #7f79d3, #e65da8);
  border-radius: 45px;
}

h2.subtitle {
  font-size: 18px;
  color: #000;
  margin-top: 2em;
}

.subtitle.underline {
  border-bottom: 1px solid #000;
  padding-bottom: 0.3em;
  display: inline-block;
}

p, li {
  font-size: 16px;
  line-height: 2.0;
}

ul, ol {
  padding-left: 1.2em;
}


.fixed-button {
  position: fixed;
  top: 1em;
  right: 1em;
  background-color: #35c5f3;
  color: white;
  padding: 1.0em 1.5em;
  border: none;
  border-radius: 45px;
  text-decoration: none;
  z-index: 1000;
  transition: opacity 0.3s ease;
}

.fixed-button:hover {
  opacity: 0.7;
}

.red-text {
  color: red;
}


@media (max-width: 600px) {
  body {
    overflow-x: hidden;
  }



  .fixed-button {
    font-size: 16px;
    font-weight: bold;
    padding: 0.5em 1.3em;

  }

  .responsive-logo {
    width: 50%;
  }



  h1.title {
    font-size: 18px;
  }

  h2.subtitle {
    font-size: 16px;
  }

  p, li {
    font-size: 14px;
  }

  .logo {
    margin-top: 6em;
  }
}