.bg_pattern {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background-color: #ffffff;
  opacity: 0.4;
  z-index: -1;
}
.Polka_v2 {
  background-image:  radial-gradient(#ffc107 2px, transparent 2px), radial-gradient(#ffc107 2px, #ffffff 2px);
  background-size: 40px 40px;
  background-position: 0 0,20px 20px;
}

body {
  background-color: #f0ebeb;
  color: rgb(142, 53, 9);
  margin: 2rem;
}

#page {
  margin: 0 auto;
  width: 900px;
}
#main {
  float: left;
  width: 900px;
}

footer {
  clear: both;
}

.image-box {
  width: 100%;
  background-color: white;
  text-align: center;
}

.image-box img {
  display: inline-block;
}

nav li {
  display: block;
  width: 130px;
  margin: 0 10px;
}

nav ul {
  display: flex;
  justify-content: center;
}

nav a {
  font-size: 18px;
  color: white;
  font-weight: bold;
  display: block;
  background: url(gray2.png) repeat-x bottom;
  line-height: 1.0;
  padding: 6px 0;
  border-radius: 8px;
  text-align: center;
  text-decoration: none;
  transition: background 0.3s ease, transform 0.2s ease;
  box-shadow: 0 2px 10px rgba(0,0,0,0.2);
}

nav a:hover {
  background-color: royalblue;
  transform: translateY(-2px); 
}

nav #current a {
  border-color: rgb(10, 48, 162);
  border-style: solid;
  border-width: 1px;
  background: linear-gradient(rgb(141, 164, 233),royalblue);
}

section {
  border-radius: 16px;
  background-color: white;
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
  padding-top: 20px;
  margin: 1rem;
  padding-bottom: 10px;
}

p {
  color: rosybrown;
  margin: 1rem;
}

h2 {
  font-family:"Yu Gothic", "游ゴシック", YuGothic, "游ゴシック体";
  font-size: 20pt;
  text-align: center;
  font-weight: bold;
  background-color: white;
  line-height: 0px;
}

h4 {
  font-family:"Yu Gothic", "游ゴシック", YuGothic, "游ゴシック体";
  color: rosybrown;
  font-size: 9pt;
  text-align: center;
  font-weight: normal;
  line-height: 1.5;
}

h5 {
  font-family:"Yu Gothic", "游ゴシック", YuGothic, "游ゴシック体";
  font-size: 12pt;
  text-align: center;
  font-weight: normal;
}

h3 {
  font-family:"Yu Gothic", "游ゴシック", YuGothic, "游ゴシック体";
  font-size: 14pt;
  border: rgb(142, 53, 9);
  border-width: 0px 0px 1px 0px;
  border-style: dashed;
  padding-left: 10px;
  margin: 1rem;
}

section a {
  padding-left: 10px;
}