a {
  color: #fffacd;
}

h1 {
  font-size: 1.75rem;
  font-weight: 700;
  color: #e6edf3;
  border-bottom: 2px solid #3b82f6;
  padding-bottom: 0.4em;
  margin: 1.5em 0 0.8em;
}

h2 {
  font-size: 1.4rem;
  font-weight: 600;
  color: #d1d5db;
  background: #252542;
  border-left: 4px solid #3b82f6;
  padding: 0.5em 0.8em;
  margin: 1.3em 0 0.6em;
  border-radius: 0 4px 4px 0;
}

h3 {
  font-size: 1.15rem;
  font-weight: 600;
  color: #c9d1d9;
  border-bottom: 1px solid #4b5563;
  padding-bottom: 0.3em;
  margin: 1.2em 0 0.5em;
}

h4 {
  font-size: 1rem;
  font-weight: 600;
  color: #9ca3af;
  position: relative;
  padding-left: 1em;
  margin: 1em 0 0.4em;
}
h4::before {
  content: "›";
  position: absolute;
  left: 0;
  color: #3b82f6;
  font-weight: bold;
}

/* #site_header 内の h1 はリセット */
#site_header h1 {
   all: revert;
}

#page-top {
    position: fixed;
    bottom: 20px;
    right: 20px;
}

/***トップへ戻るボタン***/
#page-top {
    display: block;
    font-weight: bold;
    padding: .7em;
    text-align: center;
    background: #fff; /*背景色*/
    color: #666; /*文字色*/
    transition: .3s;
}
/***マウスオーバー時***/
#page-top:hover {
    background: #666; /*背景色*/
    color: #fff; /*文字色*/
}
/***トップへ戻るボタンここまで***/