@import url('https://fonts.googleapis.com/css2?family=Noto+Serif+JP:wght@400;700&display=swap');
        
        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }

        html, body {
            height: 100%;
            overflow-x: hidden;
        }

        body {
            font-family: 'Noto Serif JP', serif;
            background: #2c2416;
            background-image: 
                repeating-linear-gradient(
                    0deg,
                    transparent,
                    transparent 50px,
                    rgba(0,0,0,0.1) 50px,
                    rgba(0,0,0,0.1) 51px
                ),
                repeating-linear-gradient(
                    90deg,
                    transparent,
                    transparent 50px,
                    rgba(0,0,0,0.1) 50px,
                    rgba(0,0,0,0.1) 51px
                );
            min-height: 100%;
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            padding: 10px;
            color: #1a1a1a;
        }

        /* ===== MENU SCREEN ===== */
        .menu-screen {
            background: linear-gradient(145deg, #e8d4a8 0%, #d4b896 100%);
            padding: 40px 50px;
            border-radius: 8px;
            box-shadow: 
                0 15px 50px rgba(0,0,0,0.5),
                inset 0 1px 0 rgba(255,255,255,0.3),
                0 0 0 4px #8b7355,
                0 0 0 8px #6b5344;
            text-align: center;
            max-width: 400px;
            width: 90%;
        }

        .menu-title {
            font-size: 2.5rem;
            margin-bottom: 5px;
            color: #2c1810;
            text-shadow: 2px 2px 0 rgba(255,255,255,0.3);
        }

        .menu-subtitle {
            font-size: 1rem;
            color: #5a4a3a;
            margin-bottom: 30px;
            letter-spacing: 2px;
        }

        .menu-section {
            margin-bottom: 20px;
            text-align: left;
        }

        .menu-section h3 {
            font-size: 0.95rem;
            color: #4a3a2a;
            margin-bottom: 10px;
            border-bottom: 2px solid #8b7355;
            padding-bottom: 5px;
        }

        .option-group {
            display: flex;
            gap: 10px;
        }

        .option-btn {
            flex: 1;
            padding: 12px 15px;
            font-family: 'Noto Serif JP', serif;
            font-size: 0.95rem;
            border: 2px solid #8b7355;
            background: #f5e6d3;
            color: #2c1810;
            border-radius: 5px;
            cursor: pointer;
            transition: all 0.2s ease;
        }

        .option-btn:hover {
            background: #e8d4a8;
        }

        .option-btn.selected {
            background: #2c1810;
            color: #f5e6d3;
            border-color: #2c1810;
        }

        .sub-settings {
            display: none;
            margin-top: 12px;
            padding: 12px;
            background: rgba(0,0,0,0.05);
            border-radius: 5px;
        }

        .sub-settings.visible {
            display: block;
        }

        .sub-settings label {
            display: block;
            margin-bottom: 8px;
            color: #4a3a2a;
            font-size: 0.9rem;
        }

        .clock-input {
            display: flex;
            align-items: center;
            gap: 10px;
        }

        .clock-input input {
            width: 70px;
            padding: 8px;
            font-family: 'Noto Serif JP', serif;
            font-size: 1rem;
            border: 2px solid #8b7355;
            border-radius: 5px;
            background: #f5e6d3;
            text-align: center;
        }

        .start-btn {
            width: 100%;
            padding: 15px 30px;
            font-family: 'Noto Serif JP', serif;
            font-size: 1.2rem;
            font-weight: bold;
            border: none;
            background: linear-gradient(145deg, #2c1810 0%, #1a0f0a 100%);
            color: #f5e6d3;
            border-radius: 5px;
            cursor: pointer;
            transition: all 0.3s ease;
            box-shadow: 0 4px 15px rgba(0,0,0,0.3);
            margin-top: 15px;
        }

        .start-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 6px 20px rgba(0,0,0,0.4);
        }

        /* ===== GAME SCREEN ===== */
        .game-screen {
            display: none;
            flex-direction: column;
            align-items: center;
            width: 100%;
            max-width: 100vw;
            height: 100%;
            padding: 5px;
        }

        .game-screen.active {
            display: flex;
        }

        .menu-screen.hidden {
            display: none;
        }

        .game-header {
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 15px;
            margin-bottom: 8px;
            flex-wrap: wrap;
            width: 100%;
        }

        .player-panel {
            display: flex;
            align-items: center;
            gap: 10px;
            padding: 8px 15px;
            background: linear-gradient(145deg, #e8d4a8 0%, #d4b896 100%);
            border-radius: 8px;
            box-shadow: 0 3px 10px rgba(0,0,0,0.3);
            transition: all 0.3s ease;
        }

        .player-panel.active {
            transform: scale(1.05);
            box-shadow: 0 0 20px rgba(255,200,100,0.5);
        }

        .player-panel.thinking {
            animation: pulse 1s ease-in-out infinite;
        }

        @keyframes pulse {
            0%, 100% { box-shadow: 0 0 20px rgba(255,200,100,0.5); }
            50% { box-shadow: 0 0 30px rgba(255,200,100,0.8); }
        }

        .player-panel.timeout {
            background: linear-gradient(145deg, #c9a8a8 0%, #b89696 100%);
        }

        .player-stone {
            width: 28px;
            height: 28px;
            border-radius: 50%;
            box-shadow: 2px 2px 6px rgba(0,0,0,0.4);
            flex-shrink: 0;
        }

        .player-stone.black {
            background: radial-gradient(circle at 30% 30%, #4a4a4a, #0a0a0a);
        }

        .player-stone.white {
            background: radial-gradient(circle at 30% 30%, #ffffff, #c0c0c0);
            border: 1px solid #999;
        }

        .player-info {
            display: flex;
            flex-direction: column;
            align-items: flex-start;
        }

        .player-name {
            font-weight: bold;
            color: #2c1810;
            font-size: 0.9rem;
            line-height: 1.2;
        }

        .player-score {
            font-size: 0.75rem;
            color: #5a4a3a;
        }

        .player-timer {
            font-size: 1.1rem;
            font-weight: bold;
            color: #2c1810;
            font-family: 'Courier New', monospace;
            margin-left: 5px;
        }

        .player-timer.warning {
            color: #c0392b;
        }

        .game-title {
            font-size: 1.4rem;
            color: #f5e6d3;
            text-shadow: 2px 2px 4px rgba(0,0,0,0.5);
            display: none;
        }

        .instruction {
            font-size: 0.85rem;
            color: #d4c4a8;
            margin-bottom: 8px;
            text-align: center;
            max-width: 400px;
        }

        /* ===== GAME BOARD ===== */
        .board-container {
            display: flex;
            align-items: center;
            justify-content: center;
            width: 100%;
            padding: 5px;
        }

        .mega-board {
            display: grid;
            gap: 4px;
            background: #8b7355;
            padding: 6px;
            border-radius: 5px;
            box-shadow: 
                0 8px 30px rgba(0,0,0,0.5),
                inset 0 1px 0 rgba(255,255,255,0.1),
                0 0 0 3px #6b5344,
                0 0 0 6px #4a3a2a;
            width: min(95vw, 70vh, 500px);
            height: min(95vw, 70vh, 500px);
        }

        .mega-board.size-3 {
            grid-template-columns: repeat(3, 1fr);
            grid-template-rows: repeat(3, 1fr);
        }

        .mega-board.size-4 {
            grid-template-columns: repeat(4, 1fr);
            grid-template-rows: repeat(4, 1fr);
        }

        .mini-board {
            display: grid;
            gap: 0;
            background: #d4b896;
            padding: 2px;
            border-radius: 2px;
            transition: all 0.3s ease;
            position: relative;
            box-shadow: inset 0 0 8px rgba(0,0,0,0.2);
        }

        .mini-board.size-3 {
            grid-template-columns: repeat(3, 1fr);
            grid-template-rows: repeat(3, 1fr);
        }

        .mini-board.size-4 {
            grid-template-columns: repeat(4, 1fr);
            grid-template-rows: repeat(4, 1fr);
        }

        .mini-board.active {
            background: #c9a86c;
            box-shadow: 
                inset 0 0 8px rgba(0,0,0,0.2),
                0 0 15px rgba(255,200,100,0.6);
        }

        .mini-board.won-black {
            background: #3a3a3a;
        }

        .mini-board.won-white {
            background: #f0f0f0;
        }

        .mini-board.draw {
            background: #a0968a;
        }

        .mini-board-overlay {
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            display: flex;
            align-items: center;
            justify-content: center;
            pointer-events: none;
            border-radius: 2px;
            z-index: 10;
            grid-column: 1 / -1;
            grid-row: 1 / -1;
        }

        .overlay-stone {
            width: 60%;
            height: 60%;
            border-radius: 50%;
            box-shadow: 3px 4px 10px rgba(0,0,0,0.5);
            display: none;
        }

        .mini-board.won-black .overlay-stone {
            display: block;
            background: radial-gradient(circle at 30% 30%, #4a4a4a, #0a0a0a);
        }

        .mini-board.won-white .overlay-stone {
            display: block;
            background: radial-gradient(circle at 30% 30%, #ffffff, #c0c0c0);
            border: 1px solid #999;
        }

        .mini-board.draw .mini-board-overlay::after {
            content: '—';
            font-size: 1.5rem;
            color: #5a4a3a;
        }

        /* ===== CELLS (Intersections) ===== */
        .cell {
            width: 100%;
            height: 100%;
            background: #d4b896;
            border: none;
            cursor: pointer;
            display: flex;
            align-items: center;
            justify-content: center;
            transition: all 0.15s ease;
            position: relative;
            padding: 0;
        }

        /* Grid lines */
        .cell::before {
            content: '';
            position: absolute;
            background: #8b7355;
            width: 1px;
            height: 100%;
            left: 50%;
            transform: translateX(-50%);
        }

        .cell::after {
            content: '';
            position: absolute;
            width: 100%;
            height: 1px;
            top: 50%;
            transform: translateY(-50%);
            background: #8b7355;
        }

        .mini-board.active .cell:not(.taken):not(.disabled) {
            background: #c9a86c;
        }

        .cell:hover:not(.taken):not(.disabled) {
            background: #bfa060;
        }

        .cell.taken, .cell.disabled {
            cursor: not-allowed;
        }

        .stone {
            width: 80%;
            height: 80%;
            border-radius: 50%;
            z-index: 1;
            box-shadow: 1px 1px 3px rgba(0,0,0,0.4);
            transition: transform 0.15s ease;
        }

        .stone.black {
            background: radial-gradient(circle at 30% 30%, #4a4a4a, #0a0a0a);
        }

        .stone.white {
            background: radial-gradient(circle at 30% 30%, #ffffff, #c0c0c0);
            border: 1px solid #aaa;
        }

        .cell:not(.taken):not(.disabled):hover .ghost-stone {
            opacity: 0.4;
        }

        .ghost-stone {
            position: absolute;
            width: 80%;
            height: 80%;
            border-radius: 50%;
            opacity: 0;
            z-index: 1;
            pointer-events: none;
            transition: opacity 0.15s ease;
        }

        .ghost-stone.black {
            background: radial-gradient(circle at 30% 30%, #4a4a4a, #0a0a0a);
        }

        .ghost-stone.white {
            background: radial-gradient(circle at 30% 30%, #ffffff, #c0c0c0);
            border: 1px solid #aaa;
        }

        /* ===== GAME MESSAGE ===== */
        .game-message {
            padding: 10px 20px;
            border-radius: 5px;
            font-size: 1.1rem;
            font-weight: bold;
            text-align: center;
            background: linear-gradient(145deg, #e8d4a8 0%, #d4b896 100%);
            box-shadow: 0 3px 10px rgba(0,0,0,0.3);
            color: #2c1810;
            opacity: 0;
            transition: opacity 0.3s ease;
            margin-top: 8px;
        }

        .game-message.visible {
            opacity: 1;
        }

        /* ===== BUTTONS ===== */
        .buttons {
            display: flex;
            gap: 8px;
            margin-top: 10px;
            flex-wrap: wrap;
            justify-content: center;
            padding-bottom: 10px;
        }

        .game-btn {
            padding: 10px 20px;
            font-family: 'Noto Serif JP', serif;
            font-size: 0.9rem;
            font-weight: bold;
            border: 2px solid #8b7355;
            border-radius: 5px;
            cursor: pointer;
            transition: all 0.3s ease;
            background: linear-gradient(145deg, #e8d4a8 0%, #d4b896 100%);
            color: #2c1810;
        }

        .game-btn:hover:not(:disabled) {
            background: linear-gradient(145deg, #d4b896 0%, #c9a86c 100%);
            transform: translateY(-1px);
        }

        .game-btn:disabled {
            opacity: 0.5;
            cursor: not-allowed;
        }

        /* ===== RESPONSIVE ===== */
        @media (max-width: 500px) {
            .menu-screen {
                padding: 25px 20px;
            }

            .menu-title {
                font-size: 2rem;
            }

            .game-header {
                gap: 8px;
            }

            .player-panel {
                padding: 6px 10px;
                gap: 8px;
            }

            .player-stone {
                width: 24px;
                height: 24px;
            }

            .player-name {
                font-size: 0.8rem;
            }

            .player-score {
                font-size: 0.7rem;
            }

            .player-timer {
                font-size: 0.95rem;
            }

            .mega-board {
                gap: 3px;
                padding: 4px;
                width: min(95vw, 60vh, 400px);
                height: min(95vw, 60vh, 400px);
            }

            .instruction {
                font-size: 0.8rem;
            }

            .game-btn {
                padding: 8px 14px;
                font-size: 0.85rem;
            }

            .game-message {
                font-size: 1rem;
                padding: 8px 15px;
            }
        }

        @media (max-height: 700px) {
            .mega-board {
                width: min(95vw, 55vh, 400px);
                height: min(95vw, 55vh, 400px);
            }

            .game-header {
                margin-bottom: 5px;
            }

            .instruction {
                margin-bottom: 5px;
            }
        }

        @media (min-width: 800px) {
            .game-title {
                display: block;
            }

            .mega-board {
                width: min(95vw, 70vh, 550px);
                height: min(95vw, 70vh, 550px);
            }
        }

        /* ===== TUTORIAL SCREEN ===== */
        .tutorial-screen {
            display: none;
            flex-direction: column;
            align-items: center;
            background: linear-gradient(145deg, #e8d4a8 0%, #d4b896 100%);
            padding: 30px;
            border-radius: 8px;
            box-shadow: 
                0 15px 50px rgba(0,0,0,0.5),
                inset 0 1px 0 rgba(255,255,255,0.3),
                0 0 0 4px #8b7355,
                0 0 0 8px #6b5344;
            max-width: 600px;
            width: 95%;
            max-height: 90vh;
            overflow-y: auto;
        }

        .tutorial-screen.active {
            display: flex;
        }

        .tutorial-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            width: 100%;
            margin-bottom: 20px;
        }

        .tutorial-title {
            font-size: 1.8rem;
            color: #2c1810;
        }

        .tutorial-close {
            background: none;
            border: none;
            font-size: 1.5rem;
            cursor: pointer;
            color: #5a4a3a;
            padding: 5px 10px;
        }

        .tutorial-close:hover {
            color: #2c1810;
        }

        .tutorial-nav {
            display: flex;
            gap: 10px;
            margin-bottom: 20px;
        }

        .tutorial-nav-btn {
            padding: 8px 16px;
            font-family: 'Noto Serif JP', serif;
            font-size: 0.9rem;
            border: 2px solid #8b7355;
            background: #f5e6d3;
            color: #2c1810;
            border-radius: 5px;
            cursor: pointer;
            transition: all 0.2s ease;
        }

        .tutorial-nav-btn:hover {
            background: #e8d4a8;
        }

        .tutorial-nav-btn.active {
            background: #2c1810;
            color: #f5e6d3;
            border-color: #2c1810;
        }

        .tutorial-content {
            width: 100%;
        }

        .tutorial-page {
            display: none;
        }

        .tutorial-page.active {
            display: block;
        }

        .tutorial-section {
            margin-bottom: 25px;
        }

        .tutorial-section h3 {
            font-size: 1.1rem;
            color: #2c1810;
            margin-bottom: 10px;
            border-bottom: 2px solid #8b7355;
            padding-bottom: 5px;
        }

        .tutorial-section p {
            color: #4a3a2a;
            line-height: 1.6;
            margin-bottom: 10px;
            font-size: 0.95rem;
        }

        .tutorial-example {
            display: flex;
            align-items: flex-start;
            gap: 20px;
            margin: 15px 0;
            padding: 15px;
            background: rgba(0,0,0,0.05);
            border-radius: 8px;
            flex-wrap: wrap;
            justify-content: center;
        }

        .tutorial-example-text {
            flex: 1;
            min-width: 200px;
        }

        .tutorial-example-text p {
            margin: 0;
        }

        /* Mini board diagrams for tutorial */
        .tutorial-diagram {
            display: inline-block;
        }

        .tutorial-mega-board {
            display: grid;
            gap: 3px;
            background: #8b7355;
            padding: 4px;
            border-radius: 4px;
        }

        .tutorial-mega-board.size-3 {
            grid-template-columns: repeat(3, 1fr);
        }

        .tutorial-mega-board.size-4 {
            grid-template-columns: repeat(4, 1fr);
        }

        .tutorial-mini-board {
            display: grid;
            gap: 1px;
            background: #d4b896;
            padding: 2px;
            border-radius: 2px;
            position: relative;
        }

        .tutorial-mini-board.size-3 {
            grid-template-columns: repeat(3, 16px);
            grid-template-rows: repeat(3, 16px);
        }

        .tutorial-mini-board.size-4 {
            grid-template-columns: repeat(4, 11px);
            grid-template-rows: repeat(4, 11px);
        }

        .tutorial-mini-board.highlight {
            background: #c9a86c;
            box-shadow: 0 0 8px rgba(255,200,100,0.6);
        }

        .tutorial-mini-board.won-black {
            background: #3a3a3a;
        }

        .tutorial-mini-board.won-white {
            background: #f0f0f0;
        }

        .tutorial-cell {
            width: 16px;
            height: 16px;
            background: #d4b896;
            display: flex;
            align-items: center;
            justify-content: center;
            position: relative;
        }

        .tutorial-mini-board.size-4 .tutorial-cell {
            width: 11px;
            height: 11px;
        }

        .tutorial-mini-board.highlight .tutorial-cell {
            background: #c9a86c;
        }

        .tutorial-cell::before {
            content: '';
            position: absolute;
            background: #8b7355;
            width: 1px;
            height: 100%;
        }

        .tutorial-cell::after {
            content: '';
            position: absolute;
            width: 100%;
            height: 1px;
            background: #8b7355;
        }

        .tutorial-stone {
            width: 12px;
            height: 12px;
            border-radius: 50%;
            z-index: 1;
        }

        .tutorial-mini-board.size-4 .tutorial-stone {
            width: 8px;
            height: 8px;
        }

        .tutorial-stone.black {
            background: radial-gradient(circle at 30% 30%, #4a4a4a, #0a0a0a);
        }

        .tutorial-stone.white {
            background: radial-gradient(circle at 30% 30%, #ffffff, #c0c0c0);
            border: 1px solid #aaa;
        }

        .tutorial-stone.highlight-stone {
            box-shadow: 0 0 6px 2px #e74c3c;
        }

        .tutorial-overlay-stone {
            width: 36px;
            height: 36px;
            border-radius: 50%;
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            z-index: 5;
        }

        .tutorial-mini-board.size-4 .tutorial-overlay-stone {
            width: 32px;
            height: 32px;
        }

        .tutorial-mini-board.won-black .tutorial-overlay-stone {
            background: radial-gradient(circle at 30% 30%, #4a4a4a, #0a0a0a);
        }

        .tutorial-mini-board.won-white .tutorial-overlay-stone {
            background: radial-gradient(circle at 30% 30%, #ffffff, #c0c0c0);
            border: 1px solid #999;
        }

        .tutorial-arrow {
            font-size: 2rem;
            color: #8b7355;
            align-self: center;
        }

        .tutorial-btn-row {
            display: flex;
            gap: 10px;
            justify-content: center;
            margin-top: 20px;
        }

        .tutorial-link {
            background: none;
            border: none;
            color: #8b7355;
            text-decoration: underline;
            cursor: pointer;
            font-family: 'Noto Serif JP', serif;
            font-size: 0.95rem;
            margin-top: 10px;
        }

        .tutorial-link:hover {
            color: #2c1810;
        }

        @media (max-width: 500px) {
            .tutorial-screen {
                padding: 20px 15px;
            }

            .tutorial-title {
                font-size: 1.4rem;
            }

            .tutorial-example {
                flex-direction: column;
                align-items: center;
            }

            .tutorial-cell {
                width: 14px;
                height: 14px;
            }

            .tutorial-stone {
                width: 10px;
                height: 10px;
            }
        }