:root {
            /* Updated Color Scheme */
            --primary-gradient: linear-gradient(135deg, #3a7bd5 0%, #00d2ff 100%);
            --primary-dark: #1e4a8b;
            --primary-light: #e6f2ff;
            --accent: #8f4fff;
            --success: #2ecc71;
            --error: #e74c3c;
            --dark-text: #2c3e50;
            --light-text: #7f8c8d;
            --card-bg: #ffffff;
            --page-bg: #f8fafc;
            
            /* Spacing & Sizing */
            --content-padding: 2.5rem;
            --element-radius: 12px;
            --card-radius: 16px;
            --element-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
            --element-shadow-hover: 0 15px 40px rgba(0, 0, 0, 0.15);
            
            /* Transitions */
            --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
        }

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

        .app-container {
            max-width: 850px;
            width: 100%;
            margin: 0 auto;
        }

        /* Header Section */
        .app-header {
            background: var(--primary-gradient);
            color: white;
            padding: 30px;
            border-radius: var(--card-radius);
            margin-bottom: 40px;
            box-shadow: var(--element-shadow);
            text-align: center;
            position: relative;
            overflow: hidden;
            animation: fadeIn 1s ease;
            z-index: 10;
        }

        .app-header::before {
            content: '';
            position: absolute;
            top: -50px;
            right: -50px;
            width: 200px;
            height: 200px;
            background: rgba(255, 255, 255, 0.15);
            border-radius: 50%;
            z-index: -1;
        }

        .app-header::after {
            content: '';
            position: absolute;
            bottom: -30px;
            left: -30px;
            width: 120px;
            height: 120px;
            background: rgba(255, 255, 255, 0.15);
            border-radius: 50%;
            z-index: -1;
        }

        .logo-section {
            display: flex;
            flex-direction: column;
            align-items: center;
            gap: 15px;
            margin-bottom: 20px;
        }

        .logo-icon {
            width: 80px;
            height: 80px;
            background: rgba(255, 255, 255, 0.2);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 36px;
            margin-bottom: 15px;
            animation: pulse 2s infinite;
        }

        .app-main-heading {
            font-size: 3.2rem;
            font-weight: 700;
            color: white;
            margin-bottom: 10px;
            text-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
            letter-spacing: -0.5px;
        }

        .app-tagline {
            font-size: 1.3rem;
            color: rgba(255, 255, 255, 0.9);
            max-width: 800px;
            margin: auto;
            line-height: 1.7;
        }

        /* Main Card */
        .conversion-main-card {
            background: var(--card-bg);
            border-radius: var(--card-radius);
            box-shadow: var(--element-shadow);
            padding: var(--content-padding);
            margin-bottom: 50px;
            position: relative;
            overflow: hidden;
            transition: var(--transition);
            border: 1px solid rgba(0, 0, 0, 0.05);
        }

        .conversion-main-card:hover {
            transform: translateY(-5px);
            box-shadow: var(--element-shadow-hover);
        }

        .card-header {
            display: flex;
            align-items: center;
            gap: 15px;
            margin-bottom: 30px;
        }

        .card-icon {
            width: 60px;
            height: 60px;
            background: var(--primary-light);
            border-radius: 15px;
            display: flex;
            align-items: center;
            justify-content: center;
            color: var(--primary-dark);
            font-size: 24px;
        }

        .card-title {
            font-size: 1rem;
            color: var(--dark-text);
            font-weight: 700;
        }

        /* Upload Area */
        .upload-interaction-area {
            border: 2px dashed var(--primary-light);
            border-radius: var(--element-radius);
            padding: 70px 30px;
            text-align: center;
            background: rgba(58, 123, 213, 0.03);
            cursor: pointer;
            margin-bottom: 30px;
            transition: var(--transition);
            position: relative;
            overflow: hidden;
        }

        .upload-interaction-area.drag-over {
            background: rgba(58, 123, 213, 0.1);
            border-color: var(--primary-dark);
        }

        .upload-prompt-icon {
            font-size: 4.5rem;
            color: var(--primary-dark);
            margin-bottom: 25px;
            transition: transform 0.4s ease;
        }

        .upload-interaction-area:hover .upload-prompt-icon {
            transform: translateY(-5px);
        }

        .upload-prompt-title {
            font-size: 1.8rem;
            color: var(--dark-text);
            margin-bottom: 10px;
            font-weight: 700;
        }

        .upload-prompt-text {
            font-size: 1.15rem;
            color: var(--light-text);
            margin-top: 10px;
            max-width: 600px;
            margin: 10px auto;
        }

        .upload-input-field {
            display: none;
        }

        .uploaded-file-display {
            font-size: 1.15rem;
            padding: 15px 25px;
            background: rgba(58, 123, 213, 0.08);
            border-radius: var(--element-radius);
            display: inline-flex;
            align-items: center;
            gap: 12px;
            color: var(--primary-dark);
            font-weight: 600;
            margin-top: 20px;
            border: 1px solid rgba(58, 123, 213, 0.2);
            transition: var(--transition);
            animation: slideUp 0.4s ease;
        }

        .uploaded-file-display:hover {
            background: rgba(58, 123, 213, 0.12);
        }

        /* Format Selector */
        .format-selection-group {
            display: flex;
            flex-direction: column;
            gap: 15px;
            margin-bottom: 30px;
        }

        .format-label-text {
            font-size: 1.15rem;
            font-weight: 600;
            color: var(--dark-text);
            display: flex;
            align-items: center;
            gap: 10px;
        }

        .format-output-dropdown {
            padding: 16px 20px;
            border: 2px solid var(--primary-light);
            border-radius: var(--element-radius);
            font-size: 1.1rem;
            background: white;
            color: var(--dark-text);
            width: auto;
            appearance: none;
            background-position: right 1rem center;
            background-size: 1.5rem;
            cursor: pointer;
            transition: var(--transition);
            font-weight: 500;
            height: auto;
        }

        .format-output-dropdown:focus {
            outline: none;
            border-color: var(--primary-dark);
            box-shadow: 0 0 0 4px rgba(58, 123, 213, 0.15);
        }

        /* Action Buttons */
        .action-button-group {
            display: flex;
            gap: 20px;
            margin-top: 30px;
            flex-wrap: wrap;
        }

        .main-action-btn, .secondary-action-btn {
            padding: 1.1rem 2.2rem;
            border: none;
            border-radius: var(--element-radius);
            font-size: 1.15rem;
            font-weight: 600;
            cursor: pointer;
            transition: var(--transition);
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 12px;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
        }

        .main-action-btn:hover, .secondary-action-btn:hover {
            transform: translateY(-3px);
            box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
        }

        .main-action-btn:active, .secondary-action-btn:active {
            transform: translateY(0);
        }

        .main-action-btn {
            background: var(--primary-gradient);
            color: white;
        }

        .main-action-btn:hover {
            background: linear-gradient(135deg, #2a63c0 0%, #00b8e6 100%);
        }

        .secondary-action-btn {
            background: #ecf0f1;
            color: var(--dark-text);
        }

        .secondary-action-btn:hover {
            background: #dfe6e9;
        }

        .loading-spinner {
            width: 24px;
            height: 24px;
            border: 3px solid rgba(255, 255, 255, 0.3);
            border-top: 3px solid rgba(255, 255, 255, 0.8);
            border-radius: 50%;
            animation: spin 1s linear infinite;
            display: none;
        }

        /* Progress Bar */
        .conversion-progress-area {
            display: none;
            margin-top: 30px;
            width: 100%;
        }

        .progress-track-bar {
            width: 100%;
            background-color: var(--primary-light);
            border-radius: 10px;
            overflow: hidden;
            height: 14px;
            box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.05);
        }

        .progress-status-bar {
            width: 0%;
            height: 100%;
            background: var(--primary-gradient);
            border-radius: 10px;
            transition: width 0.5s ease-out;
            position: relative;
            overflow: hidden;
        }

        .progress-status-bar::after {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
            animation: progressShine 1.5s infinite;
        }

        .progress-details-text {
            display: flex;
            justify-content: space-between;
            margin-top: 15px;
            font-size: 1.05rem;
            color: var(--light-text);
        }

        /* Results Display */
        .output-results-display {
            display: none;
            margin-top: 40px;
            animation: fadeIn 0.5s ease;
        }

        .results-output-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 20px;
            padding-bottom: 15px;
            border-bottom: 2px solid var(--primary-light);
        }

        .results-section-title {
            font-size: 1.8rem;
            color: var(--dark-text);
            display: flex;
            align-items: center;
            gap: 12px;
            font-weight: 700;
        }

        .results-action-buttons {
            display: flex;
            gap: 15px;
        }

        .output-data-textarea {
            width: 100%;
            min-height: 350px;
            padding: 20px;
            border: 2px solid var(--primary-light);
            border-radius: var(--element-radius);
            font-family: 'JetBrains Mono', monospace;
            font-size: 0.95rem;
            background: rgba(236, 240, 241, 0.3);
            resize: vertical;
            color: var(--dark-text);
            line-height: 1.7;
            transition: var(--transition);
        }

        .output-data-textarea:focus {
            outline: none;
            border-color: var(--primary-dark);
        }

        /* Features Grid */
        .app-feature-showcase {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 30px;
            margin-top: 60px;
        }

        .feature-item-card {
            background: var(--card-bg);
            border-radius: var(--card-radius);
            padding: 35px 30px;
            box-shadow: var(--element-shadow);
            transition: var(--transition);
            text-align: center;
            border: 1px solid rgba(0, 0, 0, 0.03);
        }

        .feature-item-card:hover {
            transform: translateY(-8px);
            box-shadow: var(--element-shadow-hover);
        }

        .feature-item-icon {
            width: 80px;
            height: 80px;
            background: var(--primary-gradient);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            margin: 0 auto 25px;
            font-size: 32px;
            color: white;
        }

        .feature-item-title {
            font-size: 1.5rem;
            margin-bottom: 15px;
            color: var(--dark-text);
            font-weight: 700;
        }

        .feature-item-description {
            color: var(--light-text);
            line-height: 1.7;
        }

        /* Notification */
        .notification {
            position: fixed;
            bottom: 25px;
            right: 25px;
            padding: 18px 28px;
            border-radius: var(--element-radius);
            box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
            color: white;
            z-index: 1000;
            display: flex;
            align-items: center;
            gap: 12px;
            opacity: 0;
            transform: translateY(-20px);
            transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
            max-width: 400px;
            backdrop-filter: blur(10px);
            background: rgba(0, 0, 0, 0.7);
        }
        .notification.success {
            background: rgba(46, 204, 113, 0.9);
        }
        .notification.error {
            background: rgba(231, 76, 60, 0.9);
        }

        /* Animations */
        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(20px); }
            to { opacity: 1; transform: translateY(0); }
        }

        @keyframes spin {
            0% { transform: rotate(0deg); }
            100% { transform: rotate(360deg); }
        }

        @keyframes progressShine {
            0% { transform: translateX(-100%); }
            100% { transform: translateX(100%); }
        }

        @keyframes slideUp {
            from { opacity: 0; transform: translateY(20px); }
            to { opacity: 1; transform: translateY(0); }
        }

        @keyframes pulse {
            0% { transform: scale(1); }
            50% { transform: scale(1.05); }
            100% { transform: scale(1); }
        }

        /* Mobile Responsiveness */
        @media (max-width: 768px) {
            .app-container {
                padding: 10px;
            }

            .app-header {
                padding: 20px;
            }

            .app-main-heading {
                font-size: 2.3rem;
            }

            .app-tagline {
                font-size: 1.1rem;
            }

            .conversion-main-card {
                padding: 30px 20px;
            }

            .upload-interaction-area {
                padding: 40px 20px;
            }

            .upload-prompt-icon {
                font-size: 3.5rem;
            }

            .upload-prompt-title {
                font-size: 1.5rem;
            }

            .card-header {
                flex-direction: row;
                text-align: center;
                gap: 15px;
            }

            .card-icon {
                margin-bottom: 10px;
            }

            .main-action-btn, .secondary-action-btn {
                padding: 16px 24px;
                font-size: 1.1rem;
                flex: 1;
                min-width: 120px;
            }

            .action-button-group {
                flex-direction: column;
                gap: 15px;
            }

            .results-action-buttons {
                flex-direction: column;
                gap: 10px;
                width: 100%;
            }

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