body {
  font-family: 'Helvetica Neue', sans-serif;
  font-size: 16px; /* PC用フォントサイズ */
  line-height: 1.7;
  color: #333;
  margin: 0;
  padding: 0;
}

/* スマホ向けにフォントサイズを少し小さくする */
@media (max-width: 768px) {
  body {
  font-size: calc(14px + 0.5vw);
  line-height: 1.7;
}
}

.container {
  max-width: 800px;
  width: 90%;
  margin: 2rem auto;
  background: #fff;
  padding: 2rem;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}


.container {
  max-width: 800px;
  margin: 2rem auto;
  background: #fff;
  padding: 2rem;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
  line-height: 1.7;
}

h1, h2, h3, h4 {
  color: #2c3e50;
  margin-top: 1.5em;
  margin-bottom: 0.5em;
}

h1 {
  font-size: 2em;
  border-bottom: 2px solid #eee;
  padding-bottom: 0.3em;
}

h2 {
  font-size: 1.5em;
  border-left: 4px solid #3ea46e;
  padding-left: 0.5em;
}

h3 {
  font-size: 1.2em;
}

p {
  margin: 1em 0;
}

ul, ol {
  margin-left: 2em;
  margin-bottom: 1em;
}

pre, code {
  background-color: #f6f8fa;
  border: 1px solid #ddd;
  border-radius: 4px;
  padding: 0.5em;
  font-family: Menlo, Monaco, Consolas, monospace;
  font-size: 0.95em;
  overflow-x: auto;
  display: block;
}

pre {
  background-color: #f0f0f0;
  padding: 1em;
}

a {
  color: #3ea46e;
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

footer {
  margin-top: 60px;
  padding-top: 20px;
  border-top: 1px solid #ddd;
  font-size: 0.9em;
  color: #777;
}

/* ヘッダー */
.site-header {
  background-color: #3ea46e;
  padding: 1rem 0;
  color: white;
  margin-bottom: 2rem;
  box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

/* ヘッダー内の container は白くしない */
.site-header .container {
  background: transparent;
  box-shadow: none;
  padding: 0 1rem;
}

/* ヘッダーの文字 */
.site-header h1 {
  margin: 0;
  font-size: 1.5rem;
}

.site-header a {
  color: white;
  text-decoration: none;
}

.site-header a:hover {
  text-decoration: underline;
}

/* 記事本文のボックス */
.article-box {
  background-color: #fff;
  border-radius: 8px;
  padding: 2rem;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
  margin-bottom: 2rem;
}

button {
  all: unset;
  background-color: #3ea46e !important;
  color: white !important;
  padding: 0.5em 1.2em !important;
  border-radius: 6px !important;
  font-size: 1rem !important;
  cursor: pointer !important;
  display: inline-block;
  text-align: center;
  transition: background-color 0.2s ease !important;
}


button:hover {
  background-color: #329a60;
}

table {
  border-collapse: collapse;
  width: 100%;
  margin: 1.5rem 0;
  font-size: 0.95rem;
}

th, td {
  border: 1px solid #ccc;
  padding: 0.6em;
  text-align: left;
  background-color: #fff;
}

th {
  background-color: #f0f0f0;
  font-weight: bold;
}


<style>
.share-button {
  background-color: #1DA1F2;
  color: white;
  width: 42px;
  height: 42px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  font-size: 20px;
  transition: transform 0.2s ease;
}

.share-button:hover {
  transform: scale(1.2);
}

.share-button.facebook {
  background-color: #4267B2;
}

.hidden-button {
  position: fixed;
  bottom: 10px;
  left: 10px;
  width: 40px;
  height: 40px;
  background: transparent;
  border: none;
  cursor: pointer;
  z-index: 1000;
  display: block; /* ← これが重要 */
}