:root {
            --bg-color: #0f0f0f;
            --bg-secondary: #1f1f1f;
            --bg-tertiary: #272727;
            --text-color: #f1f1f1;
            --text-secondary: #aaaaaa;
            --tile-bg: #1f1f1f;
            --tile-shadow: rgba(0,0,0,0.4);
            --accent: #ff0000;
            --danger: #e74c3c;
            --success: #2ecc71;
            --border-color: #3f3f3f;
            --font-main: 'Nunito', sans-serif;
        }
        * { box-sizing: border-box; margin: 0; padding: 0; user-select: none; -webkit-user-select: none; }
        body { font-family: var(--font-main); background: var(--bg-color); color: var(--text-color); overflow: hidden; touch-action: pan-y; }

        .hidden { display: none !important; }

        #app-container {
            width: 100vw;
            height: 100vh;
            display: flex;
            flex-direction: column;
            position: relative;
            transition: filter 60s linear;
        }

        /* Child View */
        #child-view { flex: 1; display: flex; flex-direction: column; padding: 1rem 1.2rem; position: relative; }
        .header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 0.5rem; }
        .clock { font-size: 2rem; font-weight: 900; color: var(--text-color); }
        .session-timer { font-size: 1rem; font-weight: 700; color: var(--text-secondary); }

        /* Child view no-api message */
        #child-no-api {
            flex: 1;
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            text-align: center;
            padding: 2rem;
            gap: 1.5rem;
        }
        #child-no-api p {
            font-size: 1.3rem;
            font-weight: 700;
            color: var(--text-secondary);
            line-height: 1.5;
        }
        #btn-watch-yt {
            font-size: 1.5rem;
            padding: 1.2rem 3rem;
            border-radius: 24px;
            background: var(--accent);
            color: white;
            border: none;
            font-weight: 900;
            cursor: pointer;
            box-shadow: 0 8px 20px rgba(255,0,0,0.3);
        }
        #btn-watch-yt:active { transform: scale(0.96); }

        .app-tile { background: var(--tile-bg); border-radius: 32px; padding: 2rem; display: flex; flex-direction: column; align-items: center; justify-content: center; cursor: pointer; box-shadow: 0 10px 25px var(--tile-shadow); transition: transform 0.2s, box-shadow 0.2s; min-height: 200px; }
        .app-tile:active { transform: scale(0.96); box-shadow: 0 5px 15px var(--tile-shadow); }
        .app-icon { font-size: 5rem; margin-bottom: 1.5rem; }
        .app-name { font-size: 1.5rem; font-weight: 800; text-align: center; color: var(--text-color); }

        /* Welcome Page */
        #welcome-page {
            position: absolute;
            top: 0; left: 0;
            width: 100%; height: 100%;
            background: var(--bg-color);
            z-index: 50;
            display: flex;
            align-items: center;
            justify-content: center;
            overflow-y: auto;
            -webkit-overflow-scrolling: touch;
            padding: 2rem 1.5rem;
        }
        #welcome-content {
            max-width: 480px;
            width: 100%;
            display: flex;
            flex-direction: column;
            align-items: center;
            text-align: center;
            gap: 1.2rem;
            padding: 1rem 0 2rem;
        }
        .welcome-logo {
            font-size: 2.2rem;
            font-weight: 900;
            color: var(--text-color);
            letter-spacing: -0.02em;
        }
        .welcome-logo span { color: #5b8af5; }
        .welcome-headline {
            font-size: clamp(2rem, 8vw, 2.8rem);
            font-weight: 900;
            line-height: 1.1;
            color: var(--text-color);
            margin: 0;
        }
        .welcome-sub {
            font-size: 1.05rem;
            color: var(--text-secondary);
            line-height: 1.6;
            max-width: 380px;
            margin: 0;
        }
        .welcome-features {
            display: flex;
            flex-direction: column;
            gap: 0.6rem;
            width: 100%;
            margin: 0.4rem 0;
        }
        .welcome-feature {
            background: var(--bg-secondary);
            border: 1px solid var(--border-color);
            border-radius: 12px;
            padding: 0.8rem 1.2rem;
            font-weight: 700;
            font-size: 0.95rem;
            text-align: left;
            color: var(--text-color);
        }
        .welcome-cta {
            width: 100%;
            font-size: 1.15rem !important;
            padding: 1rem !important;
            border-radius: 14px !important;
            margin-top: 0.3rem;
        }
        .welcome-footer {
            font-size: 0.82rem;
            color: var(--text-secondary);
            opacity: 0.5;
            margin: 0;
        }

        /* Back button */
        .back-btn { font-size: 1.2rem; font-weight: 800; padding: 1rem 2rem; border-radius: 50px; border: none; background: var(--accent); color: white; cursor: pointer; box-shadow: 0 4px 12px rgba(255,0,0,0.3); }
        .back-btn:active { transform: scale(0.95); }
        .iframe-header { display: flex; padding: 1rem 2rem; background: var(--bg-secondary); align-items: center; box-shadow: 0 1px 0 var(--border-color); z-index: 101; }

        /* Lock Screen */
        #lock-screen { position: absolute; top: 0; left: 0; width: 100%; height: 100%; background: var(--bg-color); z-index: 200; overflow-y: auto; -webkit-overflow-scrolling: touch; }
        #lock-screen-inner { min-height: 100%; display: flex; flex-direction: column; justify-content: center; align-items: center; text-align: center; padding: 2rem 1.5rem; gap: 0.8rem; }
        .lock-icon { font-size: clamp(2.5rem, 12vw, 5rem); }
        .lock-msg { font-size: clamp(1.2rem, 5vw, 1.8rem); font-weight: 900; color: var(--text-color); }
        .lock-sub { font-size: clamp(0.9rem, 3.5vw, 1.2rem); color: var(--text-secondary); font-weight: 700; }

        /* Parent Trigger */
        #parent-trigger { position: absolute; top: 0; right: 0; width: 120px; height: 120px; z-index: 250; cursor: pointer; pointer-events: auto; }

        /* Overlay & Panels */
        .overlay { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0,0,0,0.85); z-index: 300; display: flex; justify-content: center; align-items: center; padding: 1rem; user-select: auto; -webkit-user-select: auto; }
        .panel { background: var(--bg-secondary); border-radius: 24px; width: 100%; max-width: 650px; padding: 1.5rem; display: flex; flex-direction: column; position: relative; max-height: 90vh; overflow-y: auto; }
        .panel-close { position: absolute; top: 1.5rem; right: 1.5rem; font-size: 2.5rem; cursor: pointer; border: none; background: none; color: var(--text-secondary); line-height: 1; }

        /* Forms */
        h2 { margin-bottom: 1.5rem; font-size: 2rem; border-bottom: 2px solid var(--border-color); padding-bottom: 0.5rem; color: var(--text-color); }
        h3 { margin: 2rem 0 1rem; font-size: 1.4rem; color: var(--text-color); }
        .form-group { margin-bottom: 1.5rem; }
        label { display: block; font-weight: 800; margin-bottom: 0.5rem; color: var(--text-secondary); }
        input[type="number"], input[type="text"], input[type="time"], input[type="password"], select, textarea { width: 100%; padding: 1rem; border: 2px solid var(--border-color); border-radius: 12px; font-family: var(--font-main); font-size: 1.1rem; background: var(--bg-tertiary); color: var(--text-color); }
        input[type="range"] { width: 100%; margin: 1rem 0; }

        button { padding: 1rem 2rem; border: none; border-radius: 12px; font-family: var(--font-main); font-size: 1.1rem; font-weight: 800; cursor: pointer; background: var(--bg-tertiary); color: var(--text-color); transition: opacity 0.2s; }
        button:active { opacity: 0.8; }
        button.primary { background: var(--accent); color: white; }
        button.danger { background: var(--danger); color: white; }

        .flex-row { display: flex; gap: 1rem; align-items: center; flex-wrap: wrap; }
        .day-toggle { width: 48px; height: 48px; border-radius: 50%; border: 2px solid var(--border-color); display: flex; align-items: center; justify-content: center; cursor: pointer; font-weight: 800; font-size: 1.1rem; color: var(--text-secondary); }
        .day-toggle.active { background: var(--accent); color: white; border-color: var(--accent); }

        .app-list-item { display: flex; justify-content: space-between; align-items: center; padding: 1rem; border: 2px solid var(--border-color); border-radius: 12px; margin-bottom: 0.8rem; background: var(--bg-tertiary); }

        /* YouTube Container */
        #yt-container { position: absolute; top: 0; left: 0; width: 100%; height: 100%; background: var(--bg-color); z-index: 100; display: flex; flex-direction: column; }

        /* YouTube Top Bar */
        .yt-topbar {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 0.8rem 1rem;
            background: var(--bg-secondary);
            border-bottom: 1px solid var(--border-color);
            flex-shrink: 0;
        }
        .yt-logo { font-size: 1.3rem; font-weight: 900; color: var(--text-color); letter-spacing: -0.02em; }
        .yt-logo span { color: #5b8af5; }
        .yt-topbar-right { display: flex; gap: 0.5rem; align-items: center; }
        .yt-icon-btn { background: none; border: none; color: var(--text-color); font-size: 1.4rem; padding: 0.5rem; border-radius: 50%; cursor: pointer; line-height: 1; transition: background 0.15s; font-family: var(--font-main); font-weight: 800; }
        .yt-icon-btn:active { background: var(--bg-tertiary); }
        .yt-filter-bar { display: flex; gap: 0.5rem; padding: 0.6rem 0.8rem; overflow-x: auto; -webkit-overflow-scrolling: touch; scrollbar-width: none; flex-shrink: 0; background: var(--bg-color); border-bottom: 1px solid var(--border-color); position: sticky; top: 0; z-index: 1; }
        .yt-filter-bar::-webkit-scrollbar { display: none; }
        .yt-chip { flex-shrink: 0; padding: 0.4rem 0.9rem; border-radius: 20px; background: var(--bg-tertiary); color: var(--text-color); font-size: 0.85rem; font-weight: 700; cursor: pointer; white-space: nowrap; border: 1px solid var(--border-color); font-family: var(--font-main); }
        .yt-chip.active { background: var(--text-color); color: var(--bg-color); border-color: var(--text-color); }

        /* Feed */
        .yt-feed { flex: 1; overflow-y: auto; -webkit-overflow-scrolling: touch; }
        #yt-feed-grid { display: flex; flex-direction: column; max-width: 600px; margin: 0 auto; }

        /* Skeleton loading cards */
        .yt-skeleton { border-bottom: 1px solid var(--border-color); }
        .yt-skeleton-thumb { width: 100%; aspect-ratio: 16/9; background: var(--bg-tertiary); animation: shimmer 1.5s infinite; }
        .yt-skeleton-meta { display: flex; gap: 0.8rem; padding: 0.8rem 1rem 1rem; }
        .yt-skeleton-icon { width: 36px; height: 36px; border-radius: 50%; background: var(--bg-tertiary); flex-shrink: 0; animation: shimmer 1.5s infinite; }
        .yt-skeleton-text { flex: 1; display: flex; flex-direction: column; gap: 0.5rem; }
        .yt-skeleton-line { height: 14px; border-radius: 4px; background: var(--bg-tertiary); animation: shimmer 1.5s infinite; }
        .yt-skeleton-line.short { width: 50%; }
        @keyframes shimmer { 0%,100% { opacity: 1; } 50% { opacity: 0.3; } }

        /* Player view */
        #yt-player-view { flex: 1; display: flex; flex-direction: column; }
        .yt-player-bar {
            display: flex;
            align-items: center;
            justify-content: space-between;
            padding: 0.6rem 1rem;
            background: var(--bg-secondary);
            border-bottom: 1px solid var(--border-color);
            flex-shrink: 0;
        }
        .yt-back-btn {
            display: flex;
            align-items: center;
            gap: 0.4rem;
            background: var(--bg-tertiary);
            border: 1px solid var(--border-color);
            color: var(--text-color);
            font-size: 1.05rem;
            font-weight: 800;
            padding: 0.55rem 1.3rem;
            border-radius: 50px;
            cursor: pointer;
            font-family: var(--font-main);
            transition: background 0.15s, opacity 0.2s;
            white-space: nowrap;
        }
        .yt-back-btn:disabled { opacity: 0.35; cursor: not-allowed; }
        .yt-back-btn:not(:disabled):active { background: var(--bg-secondary); transform: scale(0.96); }

        .yt-unmute-btn {
            background: var(--bg-tertiary);
            color: var(--text-color);
            border: 1px solid var(--border-color);
            border-radius: 20px;
            padding: 0.4rem 1rem;
            font-size: 0.9rem;
            font-weight: 700;
            cursor: pointer;
            font-family: var(--font-main);
        }
        .yt-unmute-btn.unmuted { opacity: 0.4; }

        /* Video tiles */
        .yt-video-tile { background: var(--bg-color); cursor: pointer; transition: background 0.15s; border-bottom: 1px solid var(--border-color); }
        .yt-video-tile:active { background: var(--bg-secondary); }
        .yt-video-tile .yt-thumb-wrap { position: relative; width: 100%; aspect-ratio: 16/9; background: #111; overflow: hidden; }
        .yt-video-tile img { width: 100%; height: 100%; object-fit: cover; display: block; }
        .yt-video-tile .yt-meta { display: flex; gap: 0.8rem; padding: 0.8rem 1rem 1rem; align-items: flex-start; }
        .yt-video-tile .yt-channel-icon { width: 36px; height: 36px; border-radius: 50%; background: var(--accent); flex-shrink: 0; display: flex; align-items: center; justify-content: center; font-size: 1rem; color: white; font-weight: 800; overflow: hidden; }
        .yt-video-tile .yt-channel-icon img { width: 100%; height: 100%; object-fit: cover; }
        .yt-video-tile .yt-text { flex: 1; }
        .yt-video-tile .yt-title { font-size: 1rem; font-weight: 700; color: var(--text-color); line-height: 1.4; display: -webkit-box; -webkit-line-clamp: 2; line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; margin-bottom: 0.25rem; }
        .yt-video-tile .yt-channel-name { font-size: 0.85rem; color: var(--text-secondary); font-weight: 600; }

        #qr-container { display: flex; justify-content: center; margin: 1.5rem 0; padding: 1rem; background: var(--bg-secondary); border-radius: 12px; }
        #video-container { width: 100%; max-width: 400px; margin: 0 auto; position: relative; border-radius: 12px; overflow: hidden; }
        #qr-video { width: 100%; background: #000; display: block; }

        /* Pin / Challenge */
        .keypad { display: grid; grid-template-columns: repeat(3, 1fr); gap: 15px; max-width: 300px; margin: 0 auto; }
        .key { padding: 20px; font-size: 1.8rem; border-radius: 16px; border: none; background: var(--bg-tertiary); cursor: pointer; font-weight: 800; color: var(--text-color); box-shadow: 0 4px 6px rgba(0,0,0,0.05); }
        .key:active { transform: scale(0.95); }
        .pin-display { font-size: 2.5rem; text-align: center; letter-spacing: 0.8rem; margin-bottom: 1.5rem; min-height: 60px; font-weight: 900; color: var(--text-color); }

        .pattern-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; max-width: 250px; margin: 0 auto; }
        .pattern-dot { width: 60px; height: 60px; border-radius: 50%; background: var(--bg-tertiary); margin: auto; cursor: pointer; }
        .pattern-dot.active { background: var(--accent); }

        @media print {
            body * { visibility: hidden; }
            #qr-print-area, #qr-print-area * { visibility: visible; }
            #qr-print-area { position: absolute; left: 0; top: 0; width: 100%; padding: 2rem; }
            .panel { box-shadow: none; }
        }