* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            transition: background-color 0.3s ease, color 0.3s ease;
        }
        
        :root {
            /* Light theme variables */
            --bg-gradient-start: #1a2a6c;
            --bg-gradient-middle: #b21f1f;
            --bg-gradient-end: #fdbb2d;
            --container-bg: rgba(255, 255, 255, 0.93);
            --text-color: #333;
            --header-color: #2c3e50;
            --subtitle-color: #7f8c8d;
            --btn-bg: #3498db;
            --btn-hover: #2980b9;
            --pause-btn-bg: #e74c3c;
            --pause-btn-hover: #c0392b;
            --kanji-container-bg: white;
            --kanji-container-border: #eee;
            --active-reading-bg: #fff3a0;
            --active-reading-shadow: rgba(255, 204, 0, 0.7);
            --tooltip-bg: rgba(0, 0, 0, 0.8);
            --info-panel-bg: #f8f9fa;
            --info-panel-border: #3498db;
            --feature-bg: white;
            --feature-border: #eee;
            --progress-bg: #ecf0f1;
            --progress-bar: #2ecc71;
            --font-selector-bg: #f8f9fa;
            --font-selector-border: #eee;
            --json-viewer-bg: #2c3e50;
            --json-text: #ecf0f1;
            --json-key: #f1c40f;
            --json-value: #2ecc71;
            --footer-color: #7f8c8d;
            --footer-border: #eee;
            --theme-toggle-bg: #f1c40f;
            --theme-toggle-icon: #333;
            --sticky-header-bg: rgba(255, 255, 255, 0.95);
        }
        
        [data-theme="dark"] {
            /* Dark theme variables */
            --bg-gradient-start: #0d1b2a;
            --bg-gradient-middle: #1b263b;
            --bg-gradient-end: #415a77;
            --container-bg: rgba(30, 30, 40, 0.95);
            --text-color: #e0e0e0;
            --header-color: #aaccff;
            --subtitle-color: #a0aec0;
            --btn-bg: #4a6fa5;
            --btn-hover: #5a8fcc;
            --pause-btn-bg: #c45a5a;
            --pause-btn-hover: #d46a6a;
            --kanji-container-bg: #1e1e2e;
            --kanji-container-border: #2a2a3a;
            --active-reading-bg: #4a4a6a;
            --active-reading-shadow: rgba(100, 100, 200, 0.5);
            --tooltip-bg: rgba(50, 50, 70, 0.9);
            --info-panel-bg: #1a1a2a;
            --info-panel-border: #4a6fa5;
            --feature-bg: #252536;
            --feature-border: #2a2a3a;
            --progress-bg: #1a1a2a;
            --progress-bar: #4caf50;
            --font-selector-bg: #1a1a2a;
            --font-selector-border: #2a2a3a;
            --json-viewer-bg: #0d1b2a;
            --json-text: #d0e0f0;
            --json-key: #ffcc66;
            --json-value: #66cc99;
            --footer-color: #a0aec0;
            --footer-border: #2a2a3a;
            --theme-toggle-bg: #f1c40f;
            --theme-toggle-icon: #0d1b2a;
            --sticky-header-bg: rgba(30, 30, 40, 0.95);
        }
        
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: linear-gradient(135deg, 
                var(--bg-gradient-start), 
                var(--bg-gradient-middle), 
                var(--bg-gradient-end));
            color: var(--text-color);
            line-height: 1.6;
            min-height: 100vh;
            padding: 20px;
        }
        
        .container {
            max-width: 1000px;
            margin: 0 auto;
            background: var(--container-bg);
            border-radius: 15px;
            box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
            padding: 25px;
            /* Removed overflow: hidden which was breaking sticky positioning */
        }
        
        header {
            text-align: center;
            padding: 20px 0;
            margin-bottom: 25px;
            border-bottom: 2px solid var(--footer-border);
            position: relative;
        }
        
        h1 {
            font-size: 2.5rem;
            color: var(--header-color);
            margin-bottom: 10px;
            text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.1);
        }
        
        .subtitle {
            font-size: 1.1rem;
            color: var(--subtitle-color);
            max-width: 700px;
            margin: 0 auto;
        }
        
        .theme-toggle {
            position: absolute;
            top: 20px;
            right: 20px;
            background: var(--theme-toggle-bg);
            border: none;
            width: 40px;
            height: 40px;
            border-radius: 50%;
            cursor: pointer;
            display: flex;
            align-items: center;
            justify-content: center;
            box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
            transition: transform 0.3s ease;
        }
        
        .theme-toggle:hover {
            transform: scale(1.1);
        }
        
        .theme-toggle i {
            color: var(--theme-toggle-icon);
            font-size: 1.2rem;
        }
        
        .sticky-header {
            position: sticky;
            top: 0;
            z-index: 1000;
            background: var(--sticky-header-bg);
            padding: 15px 0;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
            margin-top: -15px;
            margin-bottom: 15px;
            border-radius: 8px;
            transition: background 0.3s ease;
        }
        
        .controls {
            display: flex;
            justify-content: center;
            gap: 15px;
            margin: 15px 0;
            flex-wrap: wrap;
        }
        
        .control-btn {
            background: var(--btn-bg);
            color: white;
            border: none;
            padding: 12px 25px;
            border-radius: 50px;
            font-size: 1rem;
            cursor: pointer;
            transition: all 0.3s ease;
            display: flex;
            align-items: center;
            gap: 8px;
            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
        }
        
        .control-btn:hover {
            background: var(--btn-hover);
            transform: translateY(-2px);
            box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
        }
        
        .control-btn:active {
            transform: translateY(0);
        }
        
        .control-btn.pause {
            background: var(--pause-btn-bg);
        }
        
        .control-btn.pause:hover {
            background: var(--pause-btn-hover);
        }
        
        .kanji-container {
            background: var(--kanji-container-bg);
            border-radius: 10px;
            padding: 30px;
            margin: 25px 0;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
            min-height: 200px;
            font-size: 2.2rem;
            line-height: 1.8;
            text-align: center;
            border: 1px solid var(--kanji-container-border);
        }
        
        /* Selected starting kanji */
.kanji-word.selected-start {
    position: relative;
    background-color: #a8e6cf;
    box-shadow: 0 0 0 2px #4CAF50;
    border-radius: 6px;
    z-index: 5;
}

.kanji-word.selected-start::after {
    content: "START";
    position: absolute;
    bottom: -20px;
    left: 50%;
    transform: translateX(-50%);
    font-size: 0.6rem;
    background: #4CAF50;
    color: white;
    padding: 2px 6px;
    border-radius: 4px;
    font-weight: bold;
}
        .kanji-word {
            display: inline-block;
            margin: 0 5px;
            padding: 5px 10px;
            border-radius: 8px;
            transition: all 0.3s ease;
            cursor: pointer;
            position: relative;
        }
        
        .kanji-word:hover {
            background: rgba(52, 152, 219, 0.1);
        }
        
        .kanji-word.active-reading {
            background: var(--active-reading-bg);
            box-shadow: 0 0 15px var(--active-reading-shadow);
            transform: scale(1.1);
            z-index: 10;
        }
        
        .kanji-word .tooltip {
            position: absolute;
            bottom: 100%;
            left: 50%;
            transform: translateX(-50%);
            background: var(--tooltip-bg);
            color: white;
            padding: 5px 10px;
            border-radius: 4px;
            font-size: 0.8rem;
            white-space: nowrap;
            opacity: 0;
            pointer-events: none;
            transition: opacity 0.3s ease;
            z-index: 100;
        }
        
        .kanji-word:hover .tooltip {
            opacity: 1;
        }
        
        .info-panel {
            background: var(--info-panel-bg);
            border-radius: 10px;
            padding: 20px;
            margin-top: 30px;
            border-left: 4px solid var(--info-panel-border);
        }
        
        .info-panel h2 {
            color: var(--header-color);
            margin-bottom: 15px;
            font-size: 1.4rem;
        }
        
        .info-panel p {
            margin-bottom: 15px;
            color: var(--text-color);
        }
        
        .features {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 20px;
            margin-top: 20px;
        }
        
        .feature {
            background: var(--feature-bg);
            padding: 15px;
            border-radius: 8px;
            box-shadow: 0 3px 10px rgba(0, 0, 0, 0.05);
            border: 1px solid var(--feature-border);
        }
        
        .feature ol, .feature ul {
            padding-left: 22px;
            margin-left: 0;
        }
        
        .feature h3 {
            color: var(--btn-bg);
            margin-bottom: 10px;
            display: flex;
            align-items: center;
            gap: 8px;
        }
        
        .progress-container {
            height: 8px;
            background: var(--progress-bg);
            border-radius: 4px;
            overflow: hidden;
            margin-top: 15px;
        }
        
        .progress-bar {
            height: 100%;
            background: var(--progress-bar);
            width: 0%;
            transition: width 0.3s ease;
        }
        
        footer {
            text-align: center;
            padding: 25px 0;
            color: var(--footer-color);
            font-size: 0.9rem;
            margin-top: 30px;
            border-top: 1px solid var(--footer-border);
        }
        
        @media (max-width: 768px) {
            .container {
                padding: 15px;
            }
            
            h1 {
                font-size: 2rem;
            }
            
            .kanji-container {
                font-size: 1.8rem;
                padding: 20px;
            }
            
            .control-btn {
                padding: 10px 20px;
            }
            
            .sticky-header {
                top: 10px; /* Slightly lower on mobile for better spacing */
            }
        }
        
        /* Font selector styles */
        .font-selector {
            background: var(--font-selector-bg);
            border-radius: 10px;
            padding: 15px;
            margin: 20px 0;
            border: 1px solid var(--font-selector-border);
        }
        
        .font-selector label {
            display: block;
            margin-bottom: 8px;
            font-weight: 500;
            color: var(--header-color);
        }
        
        .font-selector select {
            width: 100%;
            padding: 10px;
            border-radius: 8px;
            border: 1px solid var(--kanji-container-border);
            font-size: 1rem;
            background: var(--kanji-container-bg);
            color: var(--text-color);
        }
        
        .json-viewer {
            background: var(--json-viewer-bg);
            color: var(--json-text);
            border-radius: 8px;
            padding: 15px;
            margin-top: 25px;
            font-family: monospace;
            font-size: 0.9rem;
            max-height: 200px;
            overflow: auto;
        }
        
        .json-key {
            color: var(--json-key);
        }
        
        .json-value {
            color: var(--json-value);
        }

        .voice-controls {
            display: flex;
            align-items: center;
            gap: 10px;
            flex-wrap: wrap;
            margin-top: 10px;
            font-size: 0.9rem;
            background: var(--font-selector-bg);
            padding: 10px;
            border-radius: 8px;
        }

        .voice-controls label {
            margin-right: 5px;
            font-weight: bold;
            display: flex;
            align-items: center;
            gap: 5px;
        }

        .voice-controls input[type="range"] {
            width: 100px;
        }
        
        .voice-slider {
            display: flex;
            align-items: center;
            gap: 10px;
        }
        
        .debug-info {
            background: rgba(255, 0, 0, 0.1);
            padding: 10px;
            border-radius: 5px;
            margin-top: 10px;
            font-size: 0.9rem;
            display: none;
        }