body {
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.container {
    background: #f0f0f0;
    border: 8px solid #000;
    box-shadow: 
        0 0 0 2px #fff,
        0 0 0 10px #000,
        8px 8px 0 0 rgba(0,0,0,0.3);
    padding: 40px;
    width: 100%;
    max-width: 480px;
    position: relative;
    animation: slideIn 0.5s ease-out;
}