* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
            background: linear-gradient(135deg, #0a0a0f 0%, #1a1a2e 50%, #16213e 100%);
            min-height: 100vh;
            color: #e0e0e0;
            padding: 20px;
        }

        .container {
            max-width: 1600px;
            margin: 0 auto;
        }

        header {
            background: rgba(255, 255, 255, 0.05);
            backdrop-filter: blur(10px);
            border-radius: 16px;
            padding: 20px 30px;
            margin-bottom: 20px;
            border: 1px solid rgba(255, 255, 255, 0.1);
        }

        h1 {
            font-size: 28px;
            background: linear-gradient(135deg, #4facfe, #00f2fe);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            margin-bottom: 8px;
        }

        .subtitle {
            color: #a0a0a0;
            font-size: 14px;
        }

        #loading {
            text-align: center;
            padding: 100px 20px;
            font-size: 1.3em;
            color: #4facfe;
        }

        #content {
            display: none;
        }

        .air-layout {
            display: grid;
            grid-template-columns: 1fr 400px;
            gap: 20px;
            margin-bottom: 20px;
        }

        .reading-panel {
            background: rgba(255, 255, 255, 0.05);
            backdrop-filter: blur(10px);
            border-radius: 16px;
            border: 1px solid rgba(255, 255, 255, 0.1);
            overflow: hidden;
        }

        .reading-header {
            padding: 25px 30px;
            background: linear-gradient(135deg, rgba(5, 150, 105, 0.15), rgba(4, 120, 87, 0.15));
            border-bottom: 1px solid rgba(255, 255, 255, 0.1);
        }

        .reading-title {
            font-size: 32px;
            margin-bottom: 10px;
            color: #fff;
        }

        .progress-bar {
            height: 6px;
            background: rgba(0, 0, 0, 0.3);
            border-radius: 3px;
            overflow: hidden;
            margin-top: 15px;
        }

        .progress-fill {
            height: 100%;
            background: linear-gradient(90deg, #059669, #4facfe);
            width: 0%;
            transition: width 0.3s ease;
        }

        .reading-content {
            padding: 30px;
            max-height: 600px;
            overflow-y: auto;
            line-height: 1.9;
            font-size: 16px;
            color: #d0d0d0;
        }

        .reading-content p {
            margin-bottom: 20px;
        }

        .highlight-term {
            background: rgba(79, 172, 254, 0.2);
            border-bottom: 2px dotted #4facfe;
            cursor: pointer;
            padding: 0 4px;
            border-radius: 3px;
            transition: all 0.3s ease;
        }

        .highlight-term:hover {
            background: rgba(79, 172, 254, 0.4);
        }

        .comprehension-check {
            background: rgba(255, 193, 7, 0.1);
            border-left: 4px solid #ffc107;
            padding: 20px;
            margin: 25px 0;
            border-radius: 8px;
        }

        .check-question {
            color: #fff;
            font-weight: 600;
            margin-bottom: 15px;
            font-size: 15px;
        }

        .check-options {
            display: flex;
            flex-direction: column;
            gap: 10px;
        }

        .check-option {
            background: rgba(255, 255, 255, 0.05);
            padding: 12px 16px;
            border-radius: 8px;
            border: 2px solid transparent;
            cursor: pointer;
            transition: all 0.3s ease;
        }

        .check-option:hover {
            background: rgba(255, 255, 255, 0.1);
            border-color: #4facfe;
        }

        .check-option.correct {
            border-color: #10b981;
            background: rgba(16, 185, 129, 0.1);
        }

        .check-option.incorrect {
            border-color: #ef4444;
            background: rgba(239, 68, 68, 0.1);
        }

        .side-panel {
            display: flex;
            flex-direction: column;
            gap: 20px;
        }

        .panel-card {
            background: rgba(255, 255, 255, 0.05);
            backdrop-filter: blur(10px);
            border-radius: 16px;
            border: 1px solid rgba(255, 255, 255, 0.1);
            padding: 20px;
        }

        .panel-title {
            font-size: 18px;
            color: #4facfe;
            margin-bottom: 15px;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .vocab-list {
            display: flex;
            flex-direction: column;
            gap: 12px;
        }

        .vocab-item {
            background: rgba(0, 0, 0, 0.3);
            padding: 12px;
            border-radius: 8px;
            border-left: 3px solid #4facfe;
        }

        .vocab-term {
            color: #00f2fe;
            font-weight: 600;
            font-size: 14px;
            margin-bottom: 5px;
        }

        .vocab-def {
            color: #c0c0c0;
            font-size: 12px;
            line-height: 1.5;
        }

        .notes-area {
            background: rgba(0, 0, 0, 0.3);
            border: 1px solid rgba(255, 255, 255, 0.2);
            border-radius: 8px;
            padding: 12px;
            min-height: 120px;
            color: #e0e0e0;
            font-size: 13px;
            resize: vertical;
            font-family: inherit;
        }

        .chat-container {
            display: flex;
            flex-direction: column;
            height: 300px;
        }

        .chat-messages {
            flex: 1;
            overflow-y: auto;
            margin-bottom: 15px;
            display: flex;
            flex-direction: column;
            gap: 12px;
        }

        .chat-message {
            padding: 10px 14px;
            border-radius: 12px;
            font-size: 13px;
            line-height: 1.5;
            max-width: 85%;
        }

        .chat-message.user {
            background: linear-gradient(135deg, #4facfe, #00f2fe);
            color: white;
            align-self: flex-end;
        }

        .chat-message.assistant {
            background: rgba(255, 255, 255, 0.1);
            color: #e0e0e0;
            align-self: flex-start;
        }

        .chat-input-area {
            display: flex;
            gap: 10px;
        }

        .chat-input {
            flex: 1;
            background: rgba(0, 0, 0, 0.3);
            border: 1px solid rgba(255, 255, 255, 0.2);
            border-radius: 8px;
            padding: 10px;
            color: #e0e0e0;
            font-size: 13px;
            font-family: inherit;
        }

        .chat-send {
            padding: 10px 20px;
            background: linear-gradient(135deg, #059669, #047857);
            border: none;
            border-radius: 8px;
            color: white;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
        }

        .chat-send:hover {
            transform: translateY(-2px);
            box-shadow: 0 6px 20px rgba(5, 150, 105, 0.4);
        }

        .action-bar {
            display: flex;
            gap: 15px;
            justify-content: center;
            padding: 20px;
            background: rgba(255, 255, 255, 0.05);
            backdrop-filter: blur(10px);
            border-radius: 16px;
            border: 1px solid rgba(255, 255, 255, 0.1);
        }

        .nav-btn {
            padding: 12px 28px;
            background: rgba(255, 255, 255, 0.1);
            color: #4facfe;
            border: 2px solid #4facfe;
            border-radius: 10px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            font-size: 14px;
        }

        .nav-btn:hover {
            background: #4facfe;
            color: white;
            transform: translateY(-2px);
        }

        @media (max-width: 1200px) {
            .air-layout {
                grid-template-columns: 1fr;
            }
        }