ログイン/サインアップコンポーネント

<div class="flex items-center justify-center min-h-screen bg-gray-100 dark:bg-gray-900">
    <div class="bg-white dark:bg-gray-800 rounded-lg shadow-lg p-8 max-w-sm w-full">
        <h2 class="text-2xl font-semibold text-center text-gray-800 dark:text-gray-200 mb-6">Welcome</h2>
        <form>
            <div class="mb-4">
                <label class="block text-gray-700 dark:text-gray-300 mb-2" for="username">Username</label>
                <input type="text" id="username" class="border border-gray-300 dark:border-gray-700 rounded-lg w-full py-2 px-3 bg-gray-50 dark:bg-gray-700 focus:outline-none focus:ring focus:ring-blue-500" placeholder="Enter your username" required>
            </div>
            <div class="mb-4">
                <label class="block text-gray-700 dark:text-gray-300 mb-2" for="password">Password</label>
                <input type="password" id="password" class="border border-gray-300 dark:border-gray-700 rounded-lg w-full py-2 px-3 bg-gray-50 dark:bg-gray-700 focus:outline-none focus:ring focus:ring-blue-500" placeholder="Enter your password" required>
            </div>
            <div class="mb-6">
                <button type="submit" class="w-full bg-blue-500 hover:bg-blue-600 text-white font-bold py-2 rounded-lg">Login</button>
            </div>
            <div class="text-center mb-4">
                <span class="text-gray-600 dark:text-gray-400">Or</span>
            </div>
            <div class="mb-6">
                <button type="button" class="w-full bg-gray-200 dark:bg-gray-700 text-gray-800 dark:text-gray-200 font-bold py-2 rounded-lg">Signup</button>
            </div>
            <div class="text-center">
                <img class="rounded-full w-16 h-16 mx-auto" src="https://randomuser.me/api/portraits/men/1.jpg" alt="User Avatar">
            </div>
            <p class="text-center text-gray-500 dark:text-gray-400 mt-4">Need help? <a href="#" class="text-blue-500 hover:underline">Contact us</a></p>
        </form>
    </div>
</div>
<style>
@media (prefers-color-scheme: dark) {
    input:focus {
        background-color: #4A5568;
    }
    button {
        transition: background-color 0.3s;
    }
}
</style>