body {
  font-family: Arial, sans-serif;
  background: #f5f5f5;
  margin: 0;
  padding: 0;
}

.container {
  max-width: 800px;
  margin: 50px auto 0 auto;
  padding: 20px;
  background: #fff;
  border-radius: 10px 10px 0 0;
  box-shadow: 0 2px 6px rgba(0,0,0,0.2);
  display: flex;
  flex-direction: column;
}

.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
}

h1 {
  font-size: 2.5rem;
  background: linear-gradient(270deg, #00cfff, #ff66b3, #9b59b6);
  background-size: 600% 600%;
  background-clip: text;              /* 標準プロパティ（追加） */
  -webkit-background-clip: text;      /* WebKit用（既存） */
  -webkit-text-fill-color: transparent;
  color: transparent;                 /* フォールバック（追加推奨） */
  animation: gradientMove 10s ease infinite;
  margin: 0;
}

@keyframes gradientMove {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

.lang-switch select {
  padding: 0.5rem 1rem;
  font-size: 1rem;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

textarea {
  display: block;
  width: 100%;
  margin: 10px 0;
  padding: 10px 20px;
  font-size: 1rem;
  border-radius: 5px;
  border: 1px solid #ccc;
  resize: both;
  box-sizing: border-box;
}

.button-group {
  display: flex;
  justify-content: flex-end;
  margin-bottom: 10px;
}

button {
  padding: 10px 20px;
  font-size: 1rem;
  border: none;
  border-radius: 5px;
  background: #007bff;
  color: #fff;
  cursor: pointer;
}

button:hover {
  background: #0056b3;
}

h2 {
  margin-top: 30px;
  padding-bottom: 5px;
  border-bottom: 2px solid #007bff;
  color: #333;
}

p {
  line-height: 1.6;
  color: #555;
}

kbd {
  display: inline-block;
  padding: 2px 6px;
  font-family: monospace;
  font-size: 0.9em;
  color: #333;
  background-color: #f4f4f4;
  border: 1px solid #ccc;
  border-radius: 3px;
  box-shadow: 0 1px 0 rgba(0,0,0,0.2);
}

/* フッター */
.footer {
  max-width: 800px;
  margin: 0 auto 50px auto;
  background-color: #003366;
  color: #fff;
  text-align: center;
  padding: 20px;
  border-radius: 0 0 10px 10px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.2);
}

.footer a {
  color: #00cfff;
  text-decoration: none;
  margin: 0 5px;
}

.footer a:hover {
  text-decoration: underline;
}