* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Arial', sans-serif;
  background-color: #f4f7fa;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.login-container {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100%;
}

.login-box {
  background-color: #fff;
  padding: 40px;
  border-radius: 10px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
  width: 100%;
  max-width: 400px;
  text-align: center;
}

h2 {
  margin-bottom: 20px;
  font-size: 24px;
  color: #333;
}

.textbox {
  margin-bottom: 20px;
  position: relative;
}

.textbox input {
  width: 100%;
  padding: 15px;
  border: 1px solid #ccc;
  border-radius: 5px;
  font-size: 16px;
  color: #333;
}

.textbox input:focus {
  border-color: #4CAF50;
  outline: none;
}

.button-container {
  margin-top: 20px;
}

.btn {
  width: 100%;
  padding: 15px;
  background-color: #4CAF50;
  color: #fff;
  border: none;
  border-radius: 5px;
  font-size: 16px;
  cursor: pointer;
}

.btn:hover {
  background-color: #45a049;
}

.other-options {
  margin-top: 20px;
}

.other-options a {
  display: block;
  text-decoration: none;
  color: #007bff;
  font-size: 14px;
  margin-top: 10px;
}

.other-options a:hover {
  text-decoration: underline;
}

/* レスポンシブデザイン */
@media (max-width: 600px) {
  .login-box {
    padding: 20px;
  }
  
  h2 {
    font-size: 20px;
  }
  
  .textbox input {
    padding: 12px;
    font-size: 14px;
  }
  
  .btn {
    font-size: 14px;
  }
}