body {
  font-family: "Segoe UI", sans-serif;
  background: #f0f2f5;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
}

.auth-card {
  background: white;
  padding: 30px;
  border-radius: 12px;
  box-shadow: 0 10px 25px rgba(0,0,0,0.1);
  width: 360px;
}

/* タブのデザイン */
.tab-group {
  display: flex;
  background: #eee;
  border-radius: 8px;
  padding: 4px;
  margin-bottom: 25px;
}

.tab-group button {
  flex: 1;
  padding: 10px;
  border: none;
  background: none;
  cursor: pointer;
  border-radius: 6px;
  transition: 0.3s;
  font-weight: bold;
  color: #666;
}

.tab-group button.active {
  background: white;
  color: #0078d4;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

form { display: flex; flex-direction: column; gap: 15px; }
input { padding: 12px; border: 1px solid #ddd; border-radius: 6px; font-size: 1rem; }

.btn-primary { background: #0078d4; color: white; border: none; padding: 12px; border-radius: 6px; cursor: pointer; font-weight: bold; }
.btn-success { background: #28a745; color: white; border: none; padding: 12px; border-radius: 6px; cursor: pointer; font-weight: bold; }

.auth-footer { margin-top: 20px; text-align: center; font-size: 0.9em; color: #666; }
.auth-footer a { color: #0078d4; text-decoration: none; font-weight: bold; }

.status-msg { text-align: center; margin-top: 15px; font-weight: bold; }