/* === 共通：リセット & ベース設定 === */
body {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* === 共通：ヘッダー === */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 60px;
  background-color: rgba(255, 255, 255, 0.8);
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
  z-index: 9999;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 0 20px;
  box-sizing: border-box;
}

.header-inner {
  max-width: 1500px;
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.site-logo img {
  height: 50px;
}

.sns-links {
  display: flex;
  justify-content: flex-end;
  align-items: center;
}

.sns-icon {
  margin-left: 20px;
  color: #000;
  font-size: 24px;
  text-decoration: none;
}

/* === 共通：404エラーページ === */
.error-404.not-found {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  /*background-color: #f4f4f4;*/
  font-family: 'Arial', sans-serif;
}

.error-message {
  max-width: 400px;
  width: 90%;
  padding: 30px;
  background-color: #fff;
  border-radius: 8px;
  box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
  text-align: center;
}

.error-icon {
  margin-bottom: 20px;
}

.error-icon img {
  width: 80px;
  height: 80px;
  margin-bottom: 20px;
}

.error-message h1 {
  font-size: 28px;
  color: #333;
  margin-bottom: 20px;
  font-weight: 600;
}

.error-message p {
  font-size: 16px;
  color: #555;
  margin-bottom: 30px;
}

.error-message .back-home {
  display: inline-block;
  padding: 12px 25px;
  background-color: #000;
  color: #fff;
  font-size: 16px;
  text-decoration: none;
  border-radius: 30px;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
  transition: background-color 0.3s ease, transform 0.2s ease;
}

.error-message .back-home:hover {
  background-color: #333;
  transform: translateY(-2px);
}

/* === レスポンシブ対応 === */
@media (max-width: 768px) {
  .site-header {
    height: 50px;
    padding: 0 15px;
  }

  .header-inner {
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
  }

  .site-logo img {
    height: 40px;
  }

  .sns-links {
    justify-content: flex-end;
  }

  .error-message {
    padding: 25px;
  }

  .error-message h1 {
    font-size: 24px;
  }

  .error-message p {
    font-size: 14px;
  }

  .error-message .back-home {
    padding: 10px 20px;
    font-size: 14px;
  }
}

@media (max-width: 480px) {
  .site-header {
    padding: 0 10px;
  }

  .site-logo img {
    height: 40px;
  }

  .sns-links {
    margin-top: 0;
  }

  .error-message {
    padding: 20px;
  }

  .error-message h1 {
    font-size: 22px;
  }

  .error-message p {
    font-size: 12px;
  }

  .error-message .back-home {
    padding: 8px 16px;
    font-size: 12px;
  }
}