:root {
    --board-size: min(80vh, 580px); /* Change to use viewport height instead of width for better scaling */
    --light-square: #f0d9b5;
    --dark-square: #b58863;
    --selected-square: rgba(255, 255, 0, 0.3);
    --possible-move-square: rgba(20, 150, 20, 0.3);
    --check-square: rgba(220, 20, 20, 0.4);
    --info-panel-width: 320px;
    --main-bg: #1a1a1a;
    --panel-bg: #282828;
    --text-color: #e0e0e0;
    --accent-color: #4c8c8e;
    --border-radius: 6px;
    --show-coords: none; /* 'block' to show coordinates, 'none' to hide */
    --show-possible-moves: block; /* Default to show */
    --show-last-move: block; /* Default to show */
}

html {
    height: 100%;
    overflow-y: auto;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    padding: 20px;
    background-color: var(--main-bg);
    color: var(--text-color);
    box-sizing: border-box;
    overflow-y: auto; /* Add overflow to ensure content is accessible */
}

.game-container {
    display: flex;
    flex-wrap: wrap;
    gap: 24px;
    justify-content: center;
    max-width: 1200px;
    margin-top: 20px;
    margin-bottom: 20px;
}

.board-container {
    background-color: #222;
    padding: 12px;
    border-radius: 8px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.25);
    max-height: 90vh; /* Ensure it doesn't exceed viewport height */
    display: flex;
    flex-direction: column;
}

.chess-board {
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.2);
    border-radius: 2px;
    overflow: hidden;
    aspect-ratio: 1 / 1; /* Maintain square aspect ratio */
}

.game-info {
    width: var(--info-panel-width);
    background-color: var(--panel-bg);
    padding: 20px;
    border-radius: var(--border-radius);
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.2);
    height: fit-content;
    max-height: calc(var(--board-size) + 24px);
    display: flex;
    flex-direction: column;
}

.game-info h2 {
    margin-top: 0;
    text-align: center;
    border-bottom: 1px solid var(--accent-color);
    padding-bottom: 10px;
    color: var(--accent-color);
    font-size: 1.6rem;
    font-weight: 500;
    letter-spacing: 1px;
}

.move-history {
    list-style: none;
    padding: 0;
    margin: 15px 0;
    height: calc(var(--board-size) - 220px);
    overflow-y: auto;
    border: 1px solid #444;
    border-radius: var(--border-radius);
    background-color: rgba(0, 0, 0, 0.15);
    scrollbar-width: thin;
    scrollbar-color: var(--accent-color) #444;
}

.move-history::-webkit-scrollbar {
    width: 8px;
}

.move-history::-webkit-scrollbar-track {
    background: #444;
    border-radius: 4px;
}

.move-history::-webkit-scrollbar-thumb {
    background-color: var(--accent-color);
    border-radius: 4px;
}

.move-history li {
    padding: 8px 10px;
    border-bottom: 1px solid #444;
    transition: background-color 0.2s ease;
    display: grid; /* Use grid for column layout */
    grid-template-columns: 30px 1fr 1fr; /* Turn # | White Move | Black Move */
    gap: 10px;
    align-items: center;
    font-size: 0.9rem;
}

.move-history li span.turn-number {
    text-align: right;
    color: #aaa;
    font-weight: normal;
}

.move-history li span.move {
    text-align: center;
    font-weight: 500;
    min-height: 1.2em; /* Ensure alignment even if empty */
}

.move-history li:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

.move-history li:last-child {
    border-bottom: none;
}

/* Style the last move entry differently */
.move-history li.last-move-entry {
    background-color: rgba(76, 140, 142, 0.15);
    font-weight: bold;
}

.game-status {
    margin-top: auto;
    padding: 12px;
    font-weight: bold;
    text-align: center;
    background-color: rgba(0, 0, 0, 0.2);
    border-radius: var(--border-radius);
    margin-bottom: 15px;
    letter-spacing: 0.5px;
}

#undo-button {
    padding: 12px;
    font-size: 1.1em;
    cursor: pointer;
    background-color: transparent;
    color: var(--text-color);
    border: 1px solid #555;
    border-radius: var(--border-radius);
    transition: all 0.3s ease;
    font-weight: 600;
    letter-spacing: 0.5px;
    margin-right: 8px;
}

#undo-button:hover {
    background-color: rgba(255,255,255,0.06);
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

#undo-button:active {
    transform: translateY(0);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.buttons-row {
    display: flex;
    gap: 8px;
    justify-content: center;
}

#reset-button {
    padding: 12px;
    font-size: 1.1em;
    cursor: pointer;
    background-color: var(--accent-color);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    transition: all 0.3s ease;
    font-weight: 600;
    letter-spacing: 0.5px;
}

#reset-button:hover {
    background-color: #75b9bb;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

#reset-button:active {
    transform: translateY(0);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

/* Responsive adjustments */
@media (max-width: 900px) {
    :root {
        --board-size: min(85vw, 85vh); /* Adjust for mobile */
    }
    
    body {
        align-items: flex-start; /* Align to top on mobile */
        padding: 10px;
    }

    .game-container {
        flex-direction: column;
        align-items: center;
        margin-top: 10px;
    }

    .board-container {
        max-height: none; /* Remove height constraint on mobile */
    }

    .game-info {
        width: calc(var(--board-size) + 24px);
        max-height: none;
    }

    .move-history {
        height: 180px;
    }
}

/* Toggle Switch */
.toggle-container {
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 10px 0;
}

.toggle-label {
    margin-right: 10px;
    font-size: 0.9rem;
}

.switch {
    position: relative;
    display: inline-block;
    width: 44px;
    height: 24px;
}

.switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #555;
    transition: 0.4s;
    border-radius: 24px;
}

.slider:before {
    position: absolute;
    content: "";
    height: 18px;
    width: 18px;
    left: 3px;
    bottom: 3px;
    background-color: white;
    transition: 0.4s;
    border-radius: 50%;
}

input:checked + .slider {
    background-color: var(--accent-color);
}

input:checked + .slider:before {
    transform: translateX(20px);
}

body.coords-visible {
    --show-coords: block;
}

/* Settings Container */
.settings-container {
    background-color: rgba(0, 0, 0, 0.1);
    padding: 12px;
    border-radius: var(--border-radius);
    margin-bottom: 15px;
}

.game-title {
    color: var(--accent-color);
    font-size: 1.7rem;
    font-weight: 500;
    text-align: center;
    margin: 0 0 15px 0;
    letter-spacing: 1px;
}