/* Modern Reset */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    /* Premium Palette (Slate & Blue) */
    --bg-gradient: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    --text-color: #1e293b;
    --text-muted: #64748b;
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;

    /* Elegant Board Colors */
    --sq-light: #e2e8f0;
    /* Soft Blue-White */
    --sq-dark: #64748b;
    /* Cool Slate Blue */
    --sq-highlight: rgba(59, 130, 246, 0.5);
    /* Professional Blue Highlight */
    --sq-last-move: rgba(251, 191, 36, 0.4);
    /* Gentle Amber/Gold for last move */

    /* Glassmorphism */
    --panel-bg: rgba(255, 255, 255, 0.65);
    --panel-border: 1px solid rgba(255, 255, 255, 0.5);
    --backdrop-blur: 12px;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --board-shadow: 0 20px 25px -5px rgb(0 0 0 / 0.2), 0 8px 10px -6px rgb(0 0 0 / 0.1);

    --border-radius: 16px;
    --font-main: 'Outfit', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

body.dark-mode {
    --bg-gradient: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
    --text-color: #f1f5f9;
    --text-muted: #94a3b8;

    --sq-light: #334155;
    /* Dark Slate */
    --sq-dark: #1e293b;
    /* Darker Slate */
    --sq-highlight: rgba(59, 130, 246, 0.4);

    --panel-bg: rgba(30, 41, 59, 0.7);
    --panel-border: 1px solid rgba(255, 255, 255, 0.1);

    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.3);
    --board-shadow: 0 20px 25px -5px rgb(0 0 0 / 0.5), 0 8px 10px -6px rgb(0 0 0 / 0.4);
}

body {
    font-family: var(--font-main);
    background: var(--bg-gradient);
    background-attachment: fixed;
    /* Parallax-ish */
    color: var(--text-color);
    transition: color 0.3s;
    display: flex;
    justify-content: center;
    align-items: center;
    /* Center Vertically too */
    min-height: 100vh;
    padding: 20px;
}

.app-container {
    width: 100%;
    max-width: 550px;
    /* Slightly constrained for elegance */
    padding: 24px;
    display: flex;
    flex-direction: column;
    gap: 20px;
    background: var(--panel-bg);
    backdrop-filter: blur(var(--backdrop-blur));
    -webkit-backdrop-filter: blur(var(--backdrop-blur));
    border: var(--panel-border);
    border-radius: 24px;
    box-shadow: var(--shadow-lg);
}

/* Header */
.main-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    /* Subtle separator */
    padding-bottom: 15px;
    margin-bottom: 5px;
}

.logo {
    font-size: 1.6rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, var(--text-color) 0%, var(--text-muted) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.icon-btn {
    background: transparent;
    border: 1px solid rgba(0, 0, 0, 0.1);
    color: var(--text-color);
    cursor: pointer;
    padding: 8px;
    border-radius: 12px;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

body.dark-mode .icon-btn {
    border-color: rgba(255, 255, 255, 0.1);
}

.icon-btn:hover {
    background: rgba(0, 0, 0, 0.05);
    transform: translateY(-1px);
}

body.dark-mode .icon-btn:hover {
    background: rgba(255, 255, 255, 0.05);
}

.sun-icon {
    display: block;
}

.moon-icon {
    display: none;
}

body.dark-mode .sun-icon {
    display: none;
}

body.dark-mode .moon-icon {
    display: block;
}

/* Game Area */
.game-area {
    display: flex;
    flex-direction: column;
    gap: 16px;
    align-items: center;
    width: 100%;
}

.player-info {
    display: flex;
    align-items: center;
    gap: 12px;
    width: 100%;
    padding: 12px 16px;
    background: rgba(255, 255, 255, 0.4);
    border-radius: 16px;
    /* Soft neumorphic/glass feel */
}

body.dark-mode .player-info {
    background: rgba(0, 0, 0, 0.2);
}

.avatar {
    font-size: 1.4rem;
    background: var(--bg-color);
    /* Fallback */
    background: linear-gradient(135deg, #e0e7ff 0%, #e2e8f0 100%);
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 14px;
    box-shadow: var(--shadow-sm);
}

body.dark-mode .avatar {
    background: linear-gradient(135deg, #334155 0%, #1e293b 100%);
}

.info {
    display: flex;
    flex-direction: column;
    line-height: 1.3;
}

.name {
    font-weight: 700;
    font-size: 0.95rem;
}

.captures {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* Board */
.board-container {
    position: relative;
    width: 100%;
    aspect-ratio: 1;
    border-radius: 12px;
    box-shadow: var(--board-shadow);
    padding: 8px;
    /* Frame */
    background: rgba(255, 255, 255, 0.8);
    /* Frame color Light */
}

body.dark-mode .board-container {
    background: rgba(30, 41, 59, 0.8);
}

.chessboard {
    width: 100%;
    height: 100%;
    display: grid;
    grid-template-columns: repeat(8, 1fr);
    grid-template-rows: repeat(8, 1fr);
    border-radius: 6px;
    overflow: hidden;
}

.square {
    width: 100%;
    height: 100%;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
}

.square.light {
    background-color: var(--sq-light);
}

.square.dark {
    background-color: var(--sq-dark);
}

.square.selected {
    position: relative;
}

.square.selected::before {
    content: '';
    position: absolute;
    inset: 0;
    background-color: var(--sq-highlight);
    z-index: 1;
    /* Below piece */
}

.square.last-move {
    position: relative;
}

.square.last-move::before {
    content: '';
    position: absolute;
    inset: 0;
    background-color: var(--sq-last-move);
    z-index: 1;
}

/* Pieces */
.piece {
    width: 100%;
    height: 100%;
    background-size: 85%;
    /* Slightly smaller for cleaner look */
    background-repeat: no-repeat;
    background-position: center;
    cursor: grab;
    z-index: 10;
    transition: transform 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
    /* Bouncy pop */
    filter: drop-shadow(0 4px 6px rgba(0, 0, 0, 0.3));
    /* Enhanced 3D shadow */
}

.piece:hover {
    transform: translateY(-3px);
    /* Hover lift */
}

.piece:active {
    cursor: grabbing;
    transform: scale(1.1) translateY(-5px);
}

/* Dots / Rings */
.valid-move::after {
    content: '';
    position: absolute;
    width: 14%;
    /* Refined dot */
    height: 14%;
    background-color: rgba(0, 0, 0, 0.2);
    border-radius: 50%;
    z-index: 5;
}

.valid-capture::after {
    content: '';
    position: absolute;
    width: 100%;
    height: 100%;
    box-shadow: inset 0 0 0 4px rgba(0, 0, 0, 0.2);
    /* Inset ring for elegance */
    border-radius: 0;
    /* Square highlight or round? Let's use inset ring on square */
    /* Or keeping the corner triangles? No, ring is cleaner. */
}

/* Let's try corner markers for capture instead? No, circle validation is standard. */
.valid-capture::after {
    width: 85%;
    height: 85%;
    border: 4px solid rgba(0, 0, 0, 0.2);
    border-radius: 50%;
    background: transparent;
}


/* Controls */
.controls-panel {
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: 16px;
    align-items: center;
    margin-top: 10px;
}

.status-box {
    text-align: center;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-color);
    padding: 8px 16px;
    background: rgba(0, 0, 0, 0.05);
    border-radius: 20px;
}

body.dark-mode .status-box {
    background: rgba(255, 255, 255, 0.05);
}

.action-buttons {
    display: flex;
    gap: 12px;
    width: 100%;
}

.btn {
    flex: 1;
    /* Stretch buttons */
    padding: 12px 20px;
    border-radius: 12px;
    font-weight: 600;
    border: none;
    cursor: pointer;
    font-family: inherit;
    transition: all 0.2s ease;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 0.95rem;
}

.btn:active {
    transform: scale(0.98);
}

.btn.primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-hover) 100%);
    color: white;
    box-shadow: 0 4px 6px -1px rgba(37, 99, 235, 0.3);
}

.btn.primary:hover {
    box-shadow: 0 10px 15px -3px rgba(37, 99, 235, 0.4);
    transform: translateY(-1px);
}

.btn.secondary {
    background: transparent;
    color: var(--text-color);
    border: 1px solid rgba(0, 0, 0, 0.1);
}

body.dark-mode .btn.secondary {
    border-color: rgba(255, 255, 255, 0.1);
}

.btn.secondary:hover {
    background: rgba(0, 0, 0, 0.05);
}

body.dark-mode .btn.secondary:hover {
    background: rgba(255, 255, 255, 0.05);
}


/* Modal */
.modal {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(4px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    border-radius: 24px;
    /* Match container */
}

.hidden {
    display: none;
}

.modal-content {
    background: var(--panel-bg);
    padding: 30px;
    border-radius: 20px;
    text-align: center;
    box-shadow: var(--shadow-lg);
    border: var(--panel-border);
}

.promotion-options {
    display: flex;
    gap: 16px;
    margin-top: 20px;
}

.promo-btn {
    font-size: 2.5rem;
    background: transparent;
    border: 1px solid rgba(0, 0, 0, 0.1);
    border-radius: 12px;
    padding: 10px;
    cursor: pointer;
    color: var(--text-color);
    transition: all 0.2s;
}

.promo-btn:hover {
    transform: translateY(-2px);
    background: rgba(0, 0, 0, 0.05);
    box-shadow: var(--shadow-md);
}

@media (max-width: 480px) {
    .app-container {
        padding: 16px;
        border-radius: 0;
        min-height: 100vh;
        max-width: 100%;
        box-shadow: none;
    }

    body {
        padding: 0;
    }

    .logo {
        font-size: 1.4rem;
    }
}