/* Baseline CSS Variables for Dark/Light Mode */
:root {
    --bg-color: #f4f4f9;
    --text-color: #333333;
    --card-bg: #ffffff;
    --primary-color: #007bff;
    --primary-hover: #0056b3;
    --border-color: #dddddd;
    --modal-bg: rgba(0, 0, 0, 0.6);
    --highlight-color: rgba(255, 255, 51, 0.5);
    --check-color: rgba(255, 0, 0, 0.6);
    --transition-speed: 0.3s;
}

[data-theme="dark"] {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --card-bg: #1e1e1e;
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --border-color: #333333;
    --modal-bg: rgba(0, 0, 0, 0.8);
    --highlight-color: rgba(255, 215, 0, 0.4);
    --check-color: rgba(255, 51, 51, 0.7);
}

/* Global Styles */
body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    transition: background-color var(--transition-speed), color var(--transition-speed);
    margin: 0;
    padding: 20px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

.game-container {
    background: var(--card-bg);
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
    width: 100%;
    max-width: 500px; 
    transition: background-color var(--transition-speed);
    margin-bottom: 20px;
    position: relative;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    gap: 10px;
}

h1 { margin: 0; font-size: 1.5rem; flex-grow: 1; }

.icon-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-color);
    padding: 5px 10px;
    font-size: 1rem;
    cursor: pointer;
    border-radius: 6px;
    transition: background-color 0.2s;
    font-weight: bold;
}

.icon-btn:hover { background-color: rgba(0,0,0,0.05); }
[data-theme="dark"] .icon-btn:hover { background-color: rgba(255,255,255,0.1); }

#board { width: 100%; margin-bottom: 20px; border-radius: 4px; overflow: hidden; }

.highlight-square {
    box-shadow: inset 0 0 0 50px var(--highlight-color);
}

.in-check {
    box-shadow: inset 0 0 0 50px var(--check-color) !important;
}

.controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 10px;
    flex-wrap: wrap;
}

button.primary-btn, select {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 10px 15px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: bold;
    transition: background-color 0.2s, transform 0.1s, opacity 0.2s;
    flex: 1;
    min-width: 120px;
    outline: none;
}

button.primary-btn:active { transform: scale(0.98); }
select { background-color: var(--card-bg); color: var(--text-color); border: 1px solid var(--border-color); cursor: pointer;}
button.primary-btn:hover { background-color: var(--primary-hover); }

select:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    background-color: var(--border-color);
}

#status-container {
    margin-top: 15px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px;
    background-color: rgba(0,0,0,0.05);
    border-radius: 6px;
}

[data-theme="dark"] #status-container { background-color: rgba(255,255,255,0.05); }

.ai-thinking {
    font-size: 0.9rem;
    color: var(--primary-color);
    font-style: italic;
    visibility: hidden;
}
.ai-thinking.active { visibility: visible; }

footer { text-align: center; font-size: 0.85rem; opacity: 0.7; }

/* Footer Link Styles */
footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: bold;
    transition: color 0.2s;
}

footer a:hover {
    color: var(--primary-hover);
    text-decoration: underline;
}

/* Modal Styles */
#promotionModal {
    display: none;
    position: absolute;
    top: 0; left: 0; width: 100%; height: 100%;
    background: var(--modal-bg);
    border-radius: 12px;
    z-index: 1000;
    justify-content: center;
    align-items: center;
    backdrop-filter: blur(3px);
}

.modal-content {
    background: var(--card-bg);
    padding: 20px;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 10px 25px rgba(0,0,0,0.2);
}

.modal-content h3 { margin-top: 0; margin-bottom: 15px; }

.promo-pieces { display: flex; gap: 10px; justify-content: center; }

.promo-btn {
    background: var(--bg-color);
    border: 2px solid var(--border-color);
    color: var(--text-color);
    font-size: 2.5rem;
    cursor: pointer;
    padding: 10px 15px;
    border-radius: 8px;
    transition: all 0.2s;
    line-height: 1;
}

.promo-btn:hover { border-color: var(--primary-color); transform: scale(1.05); }

/* Toast Styles */
#toast {
    visibility: hidden;
    min-width: 250px;
    background-color: var(--primary-color);
    color: #fff;
    text-align: center;
    border-radius: 8px;
    padding: 12px 20px;
    position: fixed;
    z-index: 2000;
    left: 50%;
    bottom: 20px;
    transform: translateX(-50%);
    font-size: 1rem;
    font-weight: bold;
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
    opacity: 0;
    transition: opacity 0.3s, bottom 0.3s;
}

#toast.show { visibility: visible; opacity: 1; bottom: 40px; }