:root {
            --bg-color: #000000;
            --text-color: #ffffff;
            --focus-color: #ffb703;
        }

        :root[data-theme="light"] { --bg-color: #f1f5f9; --text-color: #0f172a; --focus-color: #ea580c; }
        :root[data-theme="ocean"] { --bg-color: #0f172a; --text-color: #e2e8f0; --focus-color: #38bdf8; }
        :root[data-theme="forest"] { --bg-color: #064e3b; --text-color: #ecfdf5; --focus-color: #34d399; }
        :root[data-theme="sunset"] { --bg-color: #451a03; --text-color: #ffedd5; --focus-color: #fb923c; }
        :root[data-theme="hacker"] { --bg-color: #000000; --text-color: #22c55e; --focus-color: #16a34a; }
        :root[data-theme="retro"] { --bg-color: #2e1065; --text-color: #f3e8ff; --focus-color: #d946ef; }

        body {
            margin: 0;
            padding: 0;
            display: flex;
            justify-content: center;
            align-items: center;
            min-height: 100vh;
            background-color: var(--bg-color);
            color: var(--text-color);
            font-family: 'Consolas', 'Courier New', monospace;
            overflow: hidden;
            -webkit-user-select: none;
            user-select: none;
            -webkit-touch-callout: none;
            touch-action: manipulation;
            cursor: default;
        }

        button {
            -webkit-user-select: none;
            user-select: none;
            -webkit-touch-callout: none;
            touch-action: manipulation;
        }

        .selectable {
            -webkit-user-select: text;
            user-select: text;
        }

        .sr-only {
            position: absolute;
            width: 1px;
            height: 1px;
            padding: 0;
            margin: -1px;
            overflow: hidden;
            clip: rect(0, 0, 0, 0);
            white-space: nowrap;
            border: 0;
        }

        #intro-screen {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background-color: var(--bg-color);
            display: flex;
            flex-direction: column;
            justify-content: center;
            align-items: center;
            z-index: 100;
            transition: opacity 1s ease-in-out;
        }

        .intro-title {
            font-size: 3rem;
            color: var(--text-color);
            margin-bottom: 2rem;
            text-align: center;
            text-transform: uppercase;
            letter-spacing: 5px;
        }

        .intro-instruction {
            font-size: 1.5rem;
            color: #888888;
        }

        #main-menu-container,
        #scoreboard-menu-container,
        #difficulty-menu-container {
            display: none;
            opacity: 0;
            transition: opacity 0.3s ease-in-out;
        }

        .menu-container {
            display: flex;
            flex-direction: column;
            width: 100%;
            max-width: 600px;
            padding: 2rem;
            box-sizing: border-box;
            text-align: left;
        }

        h1 {
            margin-top: 0;
            margin-bottom: 2rem;
            font-size: 2.2rem;
            letter-spacing: 2px;
            text-transform: uppercase;
            color: var(--text-color);
            border-bottom: 2px solid #333;
            padding-bottom: 10px;
        }

        .menu-nav ul {
            list-style-type: none;
            padding: 0;
            margin: 0;
            display: flex;
            flex-direction: column;
            gap: 0.5rem;
        }

        .menu-nav li {
            width: 100%;
        }

        .menu-button {
            width: 100%;
            background-color: transparent;
            color: #888888;
            border: none;
            padding: 0.8rem 1rem;
            font-size: 1.2rem;
            font-weight: normal;
            cursor: default;
            text-align: left;
            text-transform: uppercase;
            letter-spacing: 1px;
            font-family: inherit;
            position: relative;
            touch-action: manipulation;
        }

        .menu-button::before {
            content: "[ ] ";
            color: #555;
        }

        .menu-button:hover,
        .menu-button:focus-visible {
            color: var(--text-color);
            outline: none;
        }

        .menu-button:focus-visible::before {
            content: "[X] ";
            color: var(--focus-color);
        }

        .menu-button[aria-disabled="true"] {
            color: #333;
        }

        .menu-button[aria-disabled="true"]::before {
            content: "[-] ";
            color: #333;
        }

        /* Mobil Piyano Tuşları */
        /* Mobil Piyano Tuşları ve Oyundan Çıkış Barı */
        #mobile-piano-container {
            display: none;
            position: fixed;
            bottom: 0px;
            /* Ekranın tam altına yasla */
            left: 0;
            width: 100vw;
            /* Ekranı tam kapla (boydan boya) */
            z-index: 1000;
            justify-content: space-between;
            gap: 0px;
            /* Butonlar arası boşluğu sıfırla */
        }

        .mobile-piano-key {
            flex: 1;
            padding: 60px 0;
            /* Butonlar çok küçükmüş, boyları uzatıldı */
            background-color: #333;
            color: #fff;
            border: 1px solid #555;
            border-radius: 0;
            /* Arada boşluk hissi kalmaması için köşeleri sıfırla */
            margin: 0;
            font-size: 1.3rem;
            font-weight: bold;
            text-align: center;
            cursor: pointer;
            user-select: none;
            -webkit-tap-highlight-color: transparent;
            touch-action: manipulation;
            transition: background-color 0.1s;
        }

        .mobile-piano-key:active {
            background-color: var(--focus-color);
            color: #000;
        }

        .mobile-exit-btn {
            flex: 1.5;
            /* Çıkış butonu biraz daha geniş olabilir veya aynı kalabilir */
            padding: 60px 0;
            background-color: #8b0000;
            color: #fff;
            border: 1px solid #ff4444;
            border-radius: 0;
            /* Arada boşluk olmaması için */
            margin: 0;
            font-size: 1.3rem;
            font-weight: bold;
            text-align: center;
            cursor: pointer;
            user-select: none;
            -webkit-tap-highlight-color: transparent;
            touch-action: manipulation;
            transition: background-color 0.1s;
            display: none;
            /* İlk 10 saniye gizli kalacak */
        }

        .mobile-exit-btn:active {
            background-color: #ff0000;
            color: #fff;
        }

        /* Sadece oyun veya pratik modundayken mobil tuşları göster */
        body.show-mobile-keys #mobile-piano-container {
            display: flex;
        }

        /* Mobilde Enter tuşunu (diyaloglar için) göster */
        body.show-mobile-enter #mobile-enter-container {
            display: flex;
        }

        #mobile-enter-container {
            display: none;
            position: fixed;
            bottom: 10px;
            left: 50%;
            transform: translateX(-50%);
            width: 95%;
            max-width: 600px;
            z-index: 1000;
            justify-content: center;
            gap: 5px;
        }

        .mobile-enter-btn {
            flex: 1;
            padding: 15px 0;
            background-color: var(--focus-color);
            color: #000;
            border: 2px solid #555;
            border-radius: 8px;
            font-size: 1.2rem;
            font-weight: bold;
            text-align: center;
            cursor: pointer;
            user-select: none;
            -webkit-tap-highlight-color: transparent;
            touch-action: manipulation;
            transition: background-color 0.1s;
        }

        .mobile-enter-btn:active {
            background-color: #e0a300;
        }

        @media (max-width: 768px) {
            .desktop-exit-li {
                display: none;
            }
        }

        @media (min-width: 769px) {

            #mobile-piano-container,
            #mobile-enter-container {
                display: none !important;
                /* Masaüstünde/büyük ekranda gizle */
            }
        }

        /* Responsive (Mobil) Uyumlu Tasarım Eklentileri */
        @media (max-width: 600px) {
            h1 {
                font-size: 1.6rem;
                text-align: center;
                margin-bottom: 1.5rem;
            }

            .menu-container {
                padding: 1rem;
            }

            .menu-button {
                font-size: 1.05rem;
                padding: 1.2rem 1rem;
                text-align: center;
                background-color: rgba(128, 128, 128, 0.15);
                color: var(--text-color);
                border: 1px solid rgba(128, 128, 128, 0.2);
                border-radius: 14px;
                margin-bottom: 10px;
                box-sizing: border-box;
                display: flex;
                justify-content: center;
                align-items: center;
                box-shadow: 0 4px 10px rgba(0,0,0,0.08);
                transition: transform 0.08s ease, background-color 0.2s ease, box-shadow 0.2s ease;
                font-weight: 600;
                letter-spacing: 0.5px;
                line-height: 1.3;
            }

            .menu-button:active {
                background-color: rgba(128, 128, 128, 0.3);
                transform: scale(0.96);
                box-shadow: 0 2px 4px rgba(0,0,0,0.1);
            }

            .menu-button:focus-visible {
                border-color: var(--focus-color);
                background-color: rgba(128, 128, 128, 0.25);
                outline: none;
            }
            
            .menu-button[aria-disabled="true"] {
                opacity: 0.5;
                pointer-events: none;
            }

            .menu-button::before {
                content: "";
                /* Mobilde imleç efekti çok yer kaplamasın */
            }

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

            .intro-instruction {
                font-size: 1rem;
            }

            #game-score-display,
            #game-timer-display,
            #game-lives-display {
                font-size: 1rem;
            }
        }

        #feedback-menu-container,
        #server-message-container {
            position: fixed;
            top: 0;
            left: 0;
            width: 100vw;
            height: 100vh;
            background-color: rgba(0, 0, 0, 0.85);
            z-index: 2000;
            justify-content: center;
            align-items: center;
            padding: 0;
        }

        .feedback-dialog-box {
            background-color: #1a1a1a;
            padding: 30px;
            border-radius: 12px;
            box-shadow: 0 10px 40px rgba(0, 0, 0, 0.9);
            border: 1px solid #444;
            width: 90%;
            max-width: 600px;
            max-height: 85vh;
            overflow-y: auto;
            text-align: left;
            position: relative;
        }

        .feedback-dialog-box h1 {
            border-bottom: 2px solid #444;
            margin-bottom: 20px;
            font-size: 2rem;
            position: sticky;
            top: 0;
            background-color: #1a1a1a;
            padding-top: 10px;
            z-index: 10;
        }

        @media (max-width: 600px) {
            .feedback-dialog-box {
                padding: 15px;
                max-height: 95vh;
            }

            .feedback-dialog-box h1 {
                font-size: 1.5rem;
            }
        }

/* Canlı Sohbet (Live Chat) UI */
.chat-toggle-btn {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background-color: var(--focus-color);
    color: #000;
    border: 2px solid #555;
    border-radius: 50px;
    padding: 10px 20px;
    font-size: 1.2rem;
    font-weight: bold;
    cursor: pointer;
    z-index: 2000;
    box-shadow: 0 4px 10px rgba(0,0,0,0.5);
    transition: background-color 0.2s, transform 0.2s;
    font-family: inherit;
}

.chat-toggle-btn:hover, .chat-toggle-btn:focus-visible {
    background-color: #ffd766;
    transform: scale(1.05);
    outline: none;
}

.chat-panel {
    position: fixed;
    bottom: 80px;
    right: 20px;
    width: 360px;
    max-width: 90vw;
    height: 500px;
    max-height: 75vh;
    background-color: #0b141a; /* WhatsApp Koyu Arka Plan */
    border: none;
    border-radius: 12px;
    display: flex;
    flex-direction: column;
    z-index: 2000;
    box-shadow: 0 8px 25px rgba(0,0,0,0.5);
    overflow: hidden;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

.chat-header {
    background-color: #202c33; /* WhatsApp Koyu Üst Bar */
    padding: 12px 16px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid #2a3942;
}

.chat-header h2 {
    margin: 0;
    font-size: 1.15rem;
    color: #e9edef;
    font-weight: 500;
    letter-spacing: normal;
}

.chat-close-btn {
    background: transparent;
    color: #8696a0;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0 5px;
    transition: color 0.2s;
}

.chat-close-btn:hover, .chat-close-btn:focus-visible {
    color: #e9edef;
    outline: none;
}

.chat-messages-container {
    flex: 1;
    padding: 16px 14px;
    overflow-y: auto;
    background-color: #0b141a;
    background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="120" height="120" opacity="0.04"><path d="M60 0 L120 60 L60 120 L0 60 Z" fill="%23ffffff"/></svg>');
}

#chat-messages {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

/* Base Message Bubbles */
#chat-messages li {
    display: flex;
    width: 100%;
}

.wp-bubble {
    position: relative;
    max-width: 85%;
    padding: 6px 9px 8px 9px;
    border-radius: 8px;
    font-size: 0.95rem;
    line-height: 1.4;
    color: #e9edef;
    word-break: break-word;
    box-shadow: 0 1px 0.5px rgba(11,20,26,.13);
}

/* Diğer Kişilerin Mesajları (Sola yaslı, Koyu Gri) */
#chat-messages li.message-in {
    justify-content: flex-start;
}
#chat-messages li.message-in .wp-bubble {
    background-color: #202c33;
    border-top-left-radius: 0;
}

/* Benim Mesajlarım (Sağa yaslı, Acı Yeşil) */
#chat-messages li.message-out {
    justify-content: flex-end;
}
#chat-messages li.message-out .wp-bubble {
    background-color: #005c4b;
    border-top-right-radius: 0;
}

/* Sistem Mesajları (Ortalı, Elips) */
#chat-messages li.system-message {
    justify-content: center;
    margin: 8px 0;
}
#chat-messages li.system-message .wp-bubble {
    background-color: #182229;
    color: #ffd766;
    font-size: 0.8rem;
    font-style: italic;
    text-align: center;
    padding: 5px 14px;
    border-radius: 12px;
    box-shadow: none;
    max-width: 90%;
    border: 1px solid #2a3942;
}

.wp-sender {
    font-size: 0.8rem;
    font-weight: bold;
    color: #53bdeb; /* Typical group chat tag color */
    margin-bottom: 2px;
}

.wp-text {
    margin-bottom: 12px; /* Saat için boşluk */
}

/* WhatsApp Timestamp */
.wp-time {
    position: absolute;
    bottom: 4px;
    right: 8px;
    font-size: 0.65rem;
    color: rgba(255,255,255,0.6);
}

/* WhatsApp Input Area (Alt Bar) */
.chat-input-area {
    background-color: #202c33;
    padding: 10px 14px;
    display: flex;
    flex-direction: row; /* Yan yana dizilim */
    gap: 8px;
    align-items: center;
    border-top: none;
}

#chat-nickname {
    width: 25%;
    background-color: #2a3942;
    border: none;
    color: #e9edef;
    padding: 10px 12px;
    border-radius: 8px;
    font-size: 0.9rem;
}

#chat-message-input {
    flex-grow: 1;
    background-color: #2a3942;
    border: none;
    color: #e9edef;
    padding: 10px 16px;
    border-radius: 20px; /* Hap görünümü */
    font-size: 0.95rem;
}

#chat-nickname:focus, #chat-message-input:focus {
    outline: none;
}

#chat-send-btn {
    background-color: #00a884;
    color: #000;
    border: none;
    width: 42px;
    height: 42px;
    border-radius: 50%; /* Gönder butonu yuvarlak */
    font-weight: bold;
    cursor: pointer;
    font-size: 0.8rem;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    transition: background-color 0.2s, transform 0.2s;
    line-height: normal;
    padding: 0;
}

#chat-send-btn:hover, #chat-send-btn:focus-visible {
    background-color: #008f6f;
    transform: scale(1.05);
    outline: none;
}

/* WhatsApp Mobil Tam Ekran Deneyimi */
@media (max-width: 768px) {
    .chat-panel {
        width: 100vw;
        height: 100vh;
        max-height: 100vh;
        bottom: 0;
        right: 0;
        left: 0;
        border-radius: 0;
        box-shadow: none;
        border: none;
    }
    
    .chat-toggle-btn {
        bottom: 15px;
        right: 15px;
        padding: 15px 20px;
        font-size: 1.15rem;
    }

    .chat-input-area input {
        font-size: 16px !important; /* iOS Native Zoom block */
    }
}

/* --- ANLIK BİLDİRİM (TOAST) UI --- */
.toast-notification {
    position: fixed;
    bottom: 80px;
    left: 50%;
    transform: translateX(-50%);
    background: rgba(11, 20, 26, 0.95);
    color: #ffd766;
    padding: 10px 20px;
    border-radius: 20px;
    font-size: 0.95rem;
    z-index: 10000;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.3s ease-in-out, transform 0.3s ease-in-out;
    border: 1px solid #2a3942;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.6);
    text-align: center;
    max-width: 90%;
    font-weight: bold;
}

.toast-notification.show {
    opacity: 1;
    transform: translateX(-50%) translateY(-10px);
}

/* --- MOBİL TAB BAR (HOME, SOSYAL, PROFIL) --- */
#mobile-bottom-nav {
    display: none;
}

@media (max-width: 768px) {
    body.show-bottom-nav #mobile-bottom-nav {
        display: flex;
        position: fixed;
        bottom: 0;
        left: 0;
        width: 100vw;
        height: 70px;
        background-color: #1a1a1a;
        border-top: 1px solid #333;
        z-index: 1500;
        justify-content: space-around;
        align-items: center;
    }
    
    body.show-bottom-nav .chat-toggle-btn {
        bottom: 85px; /* Sohbet butonu tab barın üstünde çıksın */
    }

    .mobile-nav-btn {
        flex: 1;
        height: 100%;
        background: transparent;
        color: #888;
        border: none;
        font-size: 1rem;
        font-weight: bold;
        text-transform: uppercase;
        cursor: pointer;
        transition: color 0.2s, background-color 0.2s, border-top 0.2s;
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        border-radius: 0;
        margin: 0;
        border-top: 3px solid transparent; /* Varsayılan şeffaf kenar */
    }

    .mobile-nav-btn:active {
        background-color: #2a2a2a;
    }

    .mobile-nav-btn.active {
        color: var(--focus-color);
        border-top: 3px solid var(--focus-color);
        background-color: #2a2a2a;
    }
}
@media (min-width: 769px) {
    #mobile-bottom-nav {
         display: none !important;
    }
}