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

html, body {
    height: 100%;
    overflow: hidden;
}

.background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    transition: opacity 0.5s ease-in-out;
    z-index: -1;
}

.background.hidden {
    opacity: 0;
}

.background.visible {
    opacity: 1;
}

.sakura {
    position: absolute;
    top: -50px;
    color: pink;
    font-size: 12px;
    animation: fall linear forwards;
    pointer-events: none;
    user-select: none;
}

@keyframes fall {
    to {
        transform: translateY(110vh) rotate(360deg);
        opacity: 0;
    }
}