body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f4f4f9;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}
.container {
    text-align: center;
    padding: 2rem;
    background: white;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}
h1 { color: #333; }
.spinner {
    border: 4px solid #f3f3f3;
    border-top: 4px solid #3498db;
    border-radius: 50%;
    width: 30px;
    height: 30px;
    animation: spin 2s linear infinite;
    margin: 20px auto;
}
@keyframes spin { 0% { transform: rotate(0deg); } 100% { transform: rotate(360deg); } }