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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #0d1b2a 0%, #1b263b 50%, #0d1b2a 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #e0e1dd;
}

.login-container {
    width: 100%;
    max-width: 400px;
    padding: 20px;
}

.login-box {
    background: rgba(13, 27, 42, 0.8);
    border: 1px solid #415a77;
    border-radius: 12px;
    padding: 40px 30px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.5);
}

h1 {
    font-size: 2.5rem;
    text-align: center;
    color: #4a9eff;
    margin-bottom: 10px;
    font-weight: 700;
    letter-spacing: 2px;
}

.subtitle {
    text-align: center;
    color: #778da9;
    font-size: 0.9rem;
    margin-bottom: 30px;
}

.error-message {
    background: rgba(220, 53, 69, 0.2);
    border: 1px solid #dc3545;
    color: #ff6b6b;
    padding: 12px;
    border-radius: 6px;
    margin-bottom: 20px;
    font-size: 0.9rem;
}

.form-group {
    margin-bottom: 20px;
}

label {
    display: block;
    margin-bottom: 8px;
    color: #778da9;
    font-size: 0.9rem;
    font-weight: 500;
}

input[type="text"],
input[type="password"] {
    width: 100%;
    padding: 12px 15px;
    background: rgba(27, 38, 59, 0.6);
    border: 1px solid #415a77;
    border-radius: 6px;
    color: #e0e1dd;
    font-size: 1rem;
    transition: all 0.3s;
}

input[type="text"]:focus,
input[type="password"]:focus {
    outline: none;
    border-color: #4a9eff;
    box-shadow: 0 0 0 3px rgba(74, 158, 255, 0.1);
}

.btn-login {
    width: 100%;
    padding: 14px;
    background: linear-gradient(135deg, #4a9eff 0%, #3182ce 100%);
    border: none;
    border-radius: 6px;
    color: white;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    margin-top: 10px;
}

.btn-login:hover {
    background: linear-gradient(135deg, #3182ce 0%, #2563eb 100%);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(74, 158, 255, 0.4);
}

.btn-login:active {
    transform: translateY(0);
}

.confidential {
    text-align: center;
    color: #415a77;
    font-size: 0.75rem;
    margin-top: 30px;
    font-style: italic;
}

/* レスポンシブ */
@media (max-width: 480px) {
    .login-box {
        padding: 30px 20px;
    }
    
    h1 {
        font-size: 2rem;
    }
}