body {
    margin: 0;
    padding: 0;
    color: rgba(255, 255, 255, 0.87);
    background-color: #0f0f0f;
}

#app {
    width: 100%;
    height: 100vh;
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
}

/* Landscape-orientation prompt. Hidden by default; only shown on touch devices
   in portrait (see media query below), where the landscape board would be
   unplayably letterboxed. */
#rotate-overlay {
    display: none;
    position: fixed;
    inset: 0;
    z-index: 1000;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 24px;
    padding: 32px;
    text-align: center;
    background-color: #0f0f0f;
    color: rgba(255, 255, 255, 0.87);
    font-family: system-ui, -apple-system, sans-serif;
    font-size: 20px;
}

#rotate-overlay .rotate-icon {
    font-size: 64px;
    animation: rotate-hint 2s ease-in-out infinite;
}

@keyframes rotate-hint {
    0%, 100% { transform: rotate(-25deg); }
    50% { transform: rotate(65deg); }
}

@media (orientation: portrait) and (pointer: coarse) {
    #app { display: none; }
    #rotate-overlay { display: flex; }
}