/* ================================
   Puzzle Board - Swap Style
   ================================ */

.puzzle-board {
    display: grid;
    gap: 0;
    background: transparent;
    padding: 0;
    border-radius: 8px;
}

.puzzle-cell {
    position: relative;
    cursor: grab;
    transition: filter 0.15s ease;
    background: transparent;
    /* Prevent subpixel rendering gaps */
    background: transparent;
    border-radius: 0;
    box-sizing: border-box;
    /* Borders moved to ::after to prevent layout shifts */
    --puzzle-border-width: 5px;
    --puzzle-border-color: white;
}

/* Borders are now drawn on a pseudo-element overlay */
.puzzle-cell::after {
    content: '';
    position: absolute;
    /* Expanded by 1px to fix sub-pixel rounding errors/gaps */
    top: -1px;
    left: -1px;
    right: -1px;
    bottom: -1px;
    width: calc(101% + 2px);
    height: calc(101% + 2px);
    box-sizing: border-box;
    pointer-events: none;
    z-index: 10;

    /* Solid white border inside the element */
    border: var(--puzzle-border-width) solid var(--puzzle-border-color);
}

/* Hover effect is now applied via JavaScript to highlight entire group */
.puzzle-cell.group-hover {
    filter: brightness(1.15);
}

.puzzle-cell:active {
    cursor: grabbing;
}

/* Being dragged - invisible on board */
.puzzle-cell.being-dragged {
    opacity: 0;
}

/* Dragging clone style */
.puzzle-cell.dragging {
    cursor: grabbing;
    transform: scale(1.08);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5), 0 0 20px rgba(241, 196, 15, 0.6);
    border: 3px solid #f1c40f !important;
    border-radius: 4px;
    z-index: 1000;
}

/* Drop target highlight */
.puzzle-cell.drop-target {
    box-shadow: 0 0 25px rgba(46, 204, 113, 0.8), inset 0 0 10px rgba(46, 204, 113, 0.3);
    transform: scale(1.05);
}

/* Seamless merge - hide borders between connected pieces */
.puzzle-cell.merged-right::after {
    border-right: none;
}

.puzzle-cell.merged-bottom::after {
    border-bottom: none;
}

.puzzle-cell.merged-left::after {
    border-left: none;
}

.puzzle-cell.merged-top::after {
    border-top: none;
}

.cell-piece {
    /* STRICT alignment: 100% to match the border exactly */
    width: 100%;
    height: 100%;
    max-width: none;
    display: block;
    pointer-events: none;
}

/* Animating clone during swap */
.puzzle-cell.animating {
    cursor: default;
    transform: scale(1.05);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.4);
    border-radius: 4px;
}



/* Merge Animation */
.puzzle-cell.merge-pulse {
    animation: mergePulse 0.4s ease-out;
    z-index: 200;
}

@keyframes mergePulse {
    0% {
        filter: brightness(1);
        transform: scale(1);
    }

    50% {
        filter: brightness(1.3) drop-shadow(0 0 10px rgba(255, 255, 255, 0.6));
        transform: scale(1.03);
    }

    100% {
        filter: brightness(1);
        transform: scale(1);
    }
}

/* ================================
   Puzzle Solved - Hide all borders
   ================================ */

.puzzle-solved .puzzle-cell::after {
    border-color: transparent !important;
}

.puzzle-solved .corner-fix {
    display: none !important;
}

/* ================================
   Corner Fixes for Inner Angles
   ================================ */

.corner-fix {
    position: absolute;
    width: var(--puzzle-border-width);
    height: var(--puzzle-border-width);
    background: var(--puzzle-border-color);
    z-index: 20;
    display: none;
    pointer-events: none;
}

.puzzle-cell.fix-tr .corner-fix.tr,
.puzzle-cell.fix-tl .corner-fix.tl,
.puzzle-cell.fix-br .corner-fix.br,
.puzzle-cell.fix-bl .corner-fix.bl {
    display: block;
}

.corner-fix.tr {
    top: -1px;
    right: -1px;
}

.corner-fix.tl {
    top: -1px;
    left: -1px;
}

.corner-fix.br {
    bottom: -1px;
    right: -1px;
}

.corner-fix.bl {
    bottom: -1px;
    left: -1px;
}

/* ================================
   Hint Animations
   ================================ */

.puzzle-cell.hint-glow {
    animation: hintGlow 0.3s ease-in-out;
    z-index: 300;
}

@keyframes hintGlow {
    0% {
        filter: brightness(1);
        box-shadow: 0 0 0 rgba(241, 196, 15, 0);
    }

    50% {
        filter: brightness(1.4);
        box-shadow: 0 0 30px rgba(241, 196, 15, 0.8), 0 0 60px rgba(241, 196, 15, 0.4);
    }

    100% {
        filter: brightness(1.2);
        box-shadow: 0 0 20px rgba(241, 196, 15, 0.6);
    }
}

.puzzle-cell.hint-success {
    animation: hintSuccess 0.6s ease-out;
    z-index: 250;
}

@keyframes hintSuccess {
    0% {
        filter: brightness(1);
        transform: scale(1);
    }

    30% {
        filter: brightness(1.5) drop-shadow(0 0 15px rgba(46, 204, 113, 0.8));
        transform: scale(1.08);
    }

    100% {
        filter: brightness(1);
        transform: scale(1);
    }
}