:root {
    /* Color Scheme Variables */
    --surface: #edeff1;
    --surface-low: #e5e7eb;
    --surface-high: #d1d5db;
    --text-main: #1f2937;
    --text-subtle: #4b5563;
    --queen-color: #000000;
    --mark-color: #000000;
    --overlay-bg: rgba(240, 240, 240, 0.85);
    --icon-color: #1f2937;
    --message-success: #16a34a;
    --message-error: #dc2626;

    /* Layout Variables */
    --tile-size: 48px;
    --grid-line-width: 2px;
    --grid-line-color: rgba(0,0,0,0.03);
    --region-border-line-width: 1px;
    --region-border-color: rgba(0.7,0.7,0.7,0.9);
    --board-border-color: #cccecf;

}

.dark {
    --surface: #1f2937;
    --surface-low: #111827;
    --surface-high: #374151;
    --text-main: #f9fafb;
    --text-subtle: #9ca3af;
    --overlay-bg: rgba(0, 0, 0, 0.65);
    --icon-color: #cfcfcf;
    --message-success: #22c55e;
    --message-error: #ef4444;

    --grid-line-width: 1px;
    --grid-line-color: rgba(0,0,0,0.1);
    --region-border-line-width: 1px;
    --region-border-color: rgba(0.7,0.7,0.7,0.9);
    --board-border-color: #425065;

}

body {
    font-family: 'Poppins', sans-serif;
    background: var(--surface-high);
    color: var(--text-main);
    transition: background-color .3s, color .3s;
}

.game-container {
    background: var(--surface);
    transition: background-color .3s;
}

#loading-overlay {
    background: var(--overlay-bg);
    backdrop-filter: blur(4px);
    transition: opacity .3s;
}
#loading-overlay.hidden {
    opacity: 0;
    pointer-events: none;
}

/* Base styles for all buttons */
.btn {
    transition: background-color .2s, transform .1s, box-shadow .2s;
}
.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,.1);
}
.btn:active {
    transform: translateY(0) scale(.98);
    box-shadow: none;
}
.btn:disabled {
    opacity: .5;
    cursor: not-allowed;
    box-shadow: none;
    transform: none;
}

.theme-icon {
    color: var(--icon-color);
    transition: color 0.3s;
}

.tile {
    width: var(--tile-size);
    height: var(--tile-size);
    display: flex;
    justify-content: center;
    align-items: center;
    font-weight: bold;
    border: var(--grid-line-width) solid var(--grid-line-color);
    cursor: pointer;
    user-select: none;
    /* Add 'filter' to the transition for a smooth hover effect */
    transition: background-color .15s, transform .1s, filter .15s;
}
.tile:hover {
    /* This darkens the tile's existing color by 10% */
    filter: brightness(90%);
}
.tile.queen::after {
    content: "♕";
    font-size: 28px;
    color: var(--queen-color);
}
.tile.marked::after {
    content: "⛌";
    font-size: 20px;
    color: var(--mark-color);
}
.tile.given-queen {
    pointer-events: none;
    opacity: .8;
    background: rgba(0,0,0,.05) !important;
}

#message {
    opacity: 0;
    transform: translateY(10px);
    transition: opacity .3s, transform .3s;
}
#message.show {
    opacity: 1;
    transform: none;
}
#message.success { color: var(--message-success); }
#message.error   { color: var(--message-error); }

#rules-overlay {
    background: var(--overlay-bg);
    backdrop-filter: blur(4px);
}

.rule-img {
    background: #d1d5db;
}

.dark .rule-img {
    background: #374151;
}

.grid {
    border: 2px solid var(--board-border-color);
}