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

        .yt-title-checker {
            max-width: 800px;
            margin: 20px auto;
            padding: 20px;
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Arial, sans-serif;
            background: #fff;
            border-radius: 12px;
            box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
        }

        .tool-header {
            text-align: center;
            margin-bottom: 30px;
        }

        .tool-header h1 {
            color: #ff0000;
            font-size: 28px;
            margin-bottom: 10px;
            font-weight: 700;
        }

        .tool-header p {
            color: #666;
            font-size: 16px;
            line-height: 1.5;
        }

        .input-section {
            margin-bottom: 30px;
        }

        .input-label {
            display: block;
            color: #333;
            font-weight: 600;
            margin-bottom: 8px;
            font-size: 16px;
        }

        .title-input {
            width: 100%;
            padding: 15px;
            border: 2px solid #e0e0e0;
            border-radius: 8px;
            font-size: 16px;
            font-family: inherit;
            transition: all 0.3s ease;
            resize: vertical;
            min-height: 60px;
        }

        .title-input:focus {
            outline: none;
            border-color: #ff0000;
            box-shadow: 0 0 0 3px rgba(255, 0, 0, 0.1);
        }

        .stats-container {
            display: flex;
            flex-wrap: wrap;
            gap: 15px;
            margin: 20px 0;
        }

        .stat-box {
            flex: 1 1 120px;
            background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
            padding: 15px;
            border-radius: 8px;
            text-align: center;
            border: 1px solid #dee2e6;
            min-width: 120px;
        }

        .stat-number {
            font-size: 24px;
            font-weight: 700;
            color: #333;
            display: block;
        }

        .stat-label {
            font-size: 12px;
            color: #666;
            text-transform: uppercase;
            margin-top: 4px;
            font-weight: 500;
        }

        .length-indicator {
            margin: 20px 0;
            padding: 15px;
            border-radius: 8px;
            text-align: center;
            font-weight: 600;
            transition: all 0.3s ease;
        }

        .length-optimal {
            background: #d4edda;
            color: #155724;
            border: 1px solid #c3e6cb;
        }

        .length-warning {
            background: #fff3cd;
            color: #856404;
            border: 1px solid #ffeaa7;
        }

        .length-danger {
            background: #f8d7da;
            color: #721c24;
            border: 1px solid #f5c6cb;
        }

        .preview-section {
            margin-top: 30px;
        }

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

        .preview-title {
            color: #333;
            font-size: 20px;
            font-weight: 600;
        }

        .device-toggle {
            display: flex;
            background: #f1f3f4;
            border-radius: 6px;
            padding: 4px;
        }

        .toggle-btn {
            padding: 8px 16px;
            border: none;
            background: transparent;
            border-radius: 4px;
            cursor: pointer;
            font-size: 14px;
            font-weight: 500;
            transition: all 0.2s ease;
            color: #666;
        }

        .toggle-btn.active {
            background: #fff;
            color: #333;
            box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
        }

        .preview-container {
            border: 1px solid #e0e0e0;
            border-radius: 8px;
            overflow: hidden;
            background: #f9f9f9;
        }

        .youtube-preview {
            padding: 20px;
            background: #fff;
        }

        .desktop-preview .video-item {
            display: flex;
            gap: 12px;
            margin-bottom: 15px;
        }

        .mobile-preview .video-item {
            margin-bottom: 15px;
        }

        .thumbnail {
            flex-shrink: 0;
            background: linear-gradient(45deg, #ff0000, #cc0000);
            border-radius: 6px;
            display: flex;
            align-items: center;
            justify-content: center;
            color: white;
            font-weight: bold;
            position: relative;
        }

        .desktop-preview .thumbnail {
            width: 160px;
            height: 90px;
        }

        .mobile-preview .thumbnail {
            width: 100%;
            height: 200px;
            margin-bottom: 12px;
        }

        .play-button {
            width: 24px;
            height: 24px;
            background: rgba(0, 0, 0, 0.8);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            position: absolute;
        }

        .play-button::after {
            content: '';
            width: 0;
            height: 0;
            border-left: 6px solid white;
            border-top: 4px solid transparent;
            border-bottom: 4px solid transparent;
            margin-left: 2px;
        }

        .video-info {
            flex: 1 1 auto;
            min-width: 0;
        }

        .video-title {
            font-size: 14px;
            font-weight: 400;
            line-height: 1.4;
            color: #030303;
            margin-bottom: 4px;
            word-wrap: break-word;
            display: -webkit-box;
            -webkit-box-orient: vertical;
            overflow: hidden;
        }

        .desktop-preview .video-title {
            -webkit-line-clamp: 2;
            max-height: 2.8em;
        }

        .mobile-preview .video-title {
            font-size: 16px;
            line-height: 1.3;
            -webkit-line-clamp: 2;
            max-height: 2.6em;
        }

        .video-meta {
            font-size: 12px;
            color: #606060;
            line-height: 1.3;
        }

        .mobile-preview .video-meta {
            font-size: 13px;
        }

        .channel-name {
            margin-right: 8px;
        }

        .mobile-preview {
            display: none;
        }

        .mobile-preview.active,
        .desktop-preview.active {
            display: block;
        }

        .desktop-preview {
            display: block;
        }

        .tips-section {
            margin-top: 30px;
            padding: 20px;
            background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
            border-radius: 8px;
            border-left: 4px solid #ff0000;
        }

        .tips-title {
            color: #333;
            font-size: 18px;
            font-weight: 600;
            margin-bottom: 15px;
        }

        .tips-list {
            list-style: none;
        }

        .tips-list li {
            margin-bottom: 8px;
            color: #555;
            padding-left: 20px;
            position: relative;
        }

        .tips-list li::before {
            content: '✓';
            position: absolute;
            left: 0;
            color: #28a745;
            font-weight: bold;
        }

        @media (max-width: 768px) {
            .yt-title-checker {
                margin: 10px;
                padding: 15px;
            }

            .tool-header h1 {
                font-size: 24px;
            }

            .stats-container {
                flex-direction: column;
            }

            .stat-box {
                flex: none;
                width: 100%;
            }

            .preview-header {
                flex-direction: column;
                gap: 15px;
                align-items: flex-start;
            }
        }

        @media (min-width: 769px) and (max-width: 1024px) {
            .stats-container {
                display: flex;
                flex-wrap: wrap;
            }

            .stat-box {
                flex: 1 1 calc(50% - 7.5px);
                min-width: 140px;
            }
        }