body {
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: #f4f7f6;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

.login-card {
    background: white;
    padding: 40px;
    border-radius: 10px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    width: 100%;
    max-width: 350px;
    text-align: center;
}

.login-card h2 { margin-bottom: 10px; color: #333; }
.login-card p { color: #777; font-size: 14px; margin-bottom: 25px; }

.input-group { margin-bottom: 15px; }

input {
    width: 100%;
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 5px;
    box-sizing: border-box; /* สำคัญ: เพื่อไม่ให้ input ทะลุขอบ */
    font-size: 16px;
}

.btn-login {
    width: 100%;
    padding: 12px;
    background-color: #007bff;
    border: none;
    color: white;
    border-radius: 5px;
    cursor: pointer;
    font-size: 16px;
    transition: background 0.3s;
}

.btn-login:hover { background-color: #0056b3; }

.error-box {
    margin-top: 15px;
    padding: 10px;
    background-color: #ffebee;
    color: #c62828;
    border-radius: 5px;
    font-size: 14px;
}