html,body {
    height: 100%;
    background-color: #000;
    padding: 0;
    margin: 0;
    perspective: 1100px;
    overflow: hidden;
}

.container {
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: background 1s;
    transform-style: preserve-3d;
    will-change: transform, filter, opacity;
}

#entrer {
    width: 100px;
    height: 50px;
    background-color: #a40df6;
    border: none;
    border-radius: 5px;
    font-size: 20px;
    cursor: pointer;
    color: white;
}

.glucks {
    background-image: url('glucksmann.gif');
    background-size: 100% 100%;
    background-repeat: no-repeat;
    width: 100%;
    height: 100%;
    transform-origin: center center;
    animation: glucks-entry 1s cubic-bezier(0.2, 0.8, 0.2, 1) both;
}

@keyframes glucks-entry {
    0% {
        opacity: 1;
        clip-path: inset(49% 49% 49% 49%);
        transform: translateZ(-420px) rotateY(-24deg) rotateX(14deg) scale(0.2);
        filter: brightness(1.4) contrast(1.2);
    }
    55% {
        clip-path: inset(35% 35% 35% 35%);
        transform: translateZ(80px) rotateY(10deg) rotateX(-6deg) scale(1.15);
        filter: brightness(1.15) contrast(1.1);
    }
    100% {
        clip-path: inset(0 0 0 0);
        transform: translateZ(0) rotateX(0) rotateY(0) scale(1);
        filter: none;
    }
}