.overlay-image {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    animation: fadeIn 3s ease-in-out forwards;
}

@keyframes fadeIn {
    0% {
        opacity: 0;
        transform: translate(-50%, -50%) scale(0.5);
    }

    100% {
        opacity: 1;
        transform: translate(-50%, -50%) scale(0.9);
    }
}

.win-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.7);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.win-content {
    background: white;
    padding: 30px;
    border-radius: 10px;
    text-align: center;
    animation: popin 0.4s ease-out;
}

.win-modal.hidden {
    display: none;
}
.tile {
    display: block; /* prevents inline whitespace gaps */
    width: 150px;
    height: 150px;
    vertical-align: top;
}
.tile.active {
    outline: 3px solid #4CAF50; /* Green border */
    box-shadow: 0 0 10px #4CAF50;
    transform: scale(1.00);
    transition: transform 0.2s;
}
#puzzle {
    display: grid;
    grid-template-columns: repeat(3, 100px);
    gap: 0; /* row & column gap */
    margin-top: 0px;
    margin-bottom: 0px;
}
@keyframes popin {
    from {
        transform: scale(0.9);
        opacity: 0;
    }

    to {
        transform: scale(1);
        opacity: 1;
    }
}

.vertical-bar {
    width: 5px;
    padding: 0; /* remove Bootstrap gutter */
    margin: 5px 0px 5px 30px;
    background-color: var(--skyBlue);
}
.horizontal-bar {
    background-color: var(--skyBlue);
    height: 4px;
    width: 100%;
    margin: 40px 0px 40px 0px;
}