* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }
        
        body {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: #fff;
            min-height: 100vh;
            padding: 20px;
        }
        
        .container {
            max-width: 1200px;
            margin: 0 auto;
        }
        
        header {
            text-align: center;
            margin-bottom: 40px;
            padding-top: 20px;
        }
        
        .logo {
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 15px;
            margin-bottom: 15px;
        }
        
        .logo i {
            font-size: 3rem;
            color: #fff;
        }
        
        h1 {
            font-size: 2.8rem;
            margin-bottom: 10px;
        }
        
        .subtitle {
            font-size: 1.1rem;
            color: rgba(255,255,255,0.9);
            max-width: 600px;
            margin: 0 auto 25px;
            line-height: 1.6;
        }
        
        .converter-box {
            background: rgba(255, 255, 255, 0.1);
            border-radius: 20px;
            padding: 30px;
            margin-bottom: 40px;
            border: 1px solid rgba(255, 255, 255, 0.2);
        }
        
        .upload-area {
            border: 3px dashed #fff;
            border-radius: 15px;
            padding: 50px 30px;
            text-align: center;
            margin-bottom: 30px;
            transition: all 0.3s ease;
            cursor: pointer;
            position: relative;
            overflow: hidden;
        }
        
        .upload-area:hover {
            background: rgba(255, 255, 255, 0.1);
        }
        
        .upload-area i {
            font-size: 4rem;
            color: #fff;
            margin-bottom: 20px;
        }
        
        .upload-area h3 {
            font-size: 1.8rem;
            margin-bottom: 15px;
        }
        
        .upload-area p {
            color: rgba(255,255,255,0.8);
            margin-bottom: 20px;
        }
        
        .file-size-info {
            background: rgba(0, 0, 0, 0.3);
            padding: 10px 20px;
            border-radius: 30px;
            display: inline-block;
            font-weight: bold;
            color: #fff;
            border: 2px solid rgba(255,255,255,0.3);
        }
        
        #pptInput {
            position: absolute;
            width: 100%;
            height: 100%;
            top: 0;
            left: 0;
            opacity: 0;
            cursor: pointer;
        }
        
        .file-info {
            background: rgba(255, 255, 255, 0.1);
            border-radius: 15px;
            padding: 20px;
            margin-bottom: 30px;
            display: none;
        }
        
        .file-info h4 {
            margin-bottom: 15px;
            display: flex;
            align-items: center;
            gap: 10px;
        }
        
        .file-details {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 15px;
        }
        
        .detail-item {
            background: rgba(0, 0, 0, 0.2);
            padding: 15px;
            border-radius: 10px;
        }
        
        .detail-label {
            font-weight: 600;
            color: rgba(255,255,255,0.8);
            margin-bottom: 5px;
            font-size: 0.9rem;
        }
        
        .detail-value {
            font-size: 1.1rem;
        }
        
        .controls {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 20px;
            margin-bottom: 30px;
        }
        
        .control-group {
            background: rgba(255, 255, 255, 0.1);
            padding: 20px;
            border-radius: 12px;
        }
        
        .control-group label {
            display: block;
            margin-bottom: 10px;
            font-weight: 600;
            font-size: 1.1rem;
            display: flex;
            align-items: center;
            gap: 10px;
        }
        
        select {
            width: 100%;
            padding: 12px;
            border-radius: 8px;
            border: 2px solid rgba(255,255,255,0.3);
            background: rgba(0, 0, 0, 0.3);
            color: white;
            font-size: 1rem;
            outline: none;
        }
        
        select:focus {
            border-color: #fff;
        }
        
        select option {
            background: #764ba2;
            color: white;
        }
        
        .buttons {
            display: flex;
            justify-content: center;
            gap: 20px;
            margin: 30px 0;
        }
        
        .btn {
            padding: 15px 35px;
            border-radius: 10px;
            border: none;
            font-size: 1.1rem;
            font-weight: 600;
            cursor: pointer;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 10px;
            transition: all 0.3s ease;
            min-width: 200px;
        }
        
        .btn-convert {
            background: #4CAF50;
            color: white;
        }
        
        .btn-convert:hover:not(:disabled) {
            opacity: 0.9;
        }
        
        .btn-download {
            background: #2196F3;
            color: white;
        }
        
        .btn-download:hover:not(:disabled) {
            opacity: 0.9;
        }
        
        .btn:disabled {
            opacity: 0.5;
            cursor: not-allowed;
        }
        
        .status-box {
            background: rgba(0, 0, 0, 0.3);
            border-radius: 15px;
            padding: 25px;
            margin-top: 30px;
        }
        
        .status-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 15px;
        }
        
        .status-header h3 {
            font-size: 1.5rem;
            display: flex;
            align-items: center;
            gap: 10px;
        }
        
        .timer {
            background: rgba(255, 255, 255, 0.1);
            padding: 8px 16px;
            border-radius: 20px;
            font-weight: bold;
        }
        
        .progress-container {
            background: rgba(255, 255, 255, 0.1);
            height: 10px;
            border-radius: 5px;
            overflow: hidden;
            margin-bottom: 20px;
        }
        
        .progress-bar {
            height: 100%;
            background: linear-gradient(90deg, #4CAF50, #2196F3);
            width: 0%;
            transition: width 0.3s ease;
        }
        
        .status-text {
            color: rgba(255,255,255,0.9);
            font-size: 1rem;
            min-height: 24px;
            padding: 15px;
            background: rgba(0, 0, 0, 0.3);
            border-radius: 8px;
        }
        
        .properties-box {
            background: rgba(255, 255, 255, 0.1);
            border-radius: 20px;
            padding: 30px;
            margin-top: 30px;
            display: none;
        }
        
        .properties-box.active {
            display: block;
        }
        
        .properties-box h3 {
            font-size: 1.5rem;
            margin-bottom: 20px;
            display: flex;
            align-items: center;
            gap: 10px;
        }
        
        .properties-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
            gap: 20px;
        }
        
        .property-item {
            background: rgba(0, 0, 0, 0.2);
            padding: 20px;
            border-radius: 10px;
        }
        
        .property-label {
            font-weight: 600;
            color: rgba(255,255,255,0.8);
            margin-bottom: 8px;
            font-size: 1rem;
        }
        
        .property-value {
            font-size: 1.1rem;
        }
        
        footer {
            text-align: center;
            margin-top: 50px;
            padding: 20px;
            color: rgba(255,255,255,0.8);
            font-size: 0.9rem;
            border-top: 1px solid rgba(255, 255, 255, 0.2);
        }
        
        .loader {
            display: inline-block;
            width: 20px;
            height: 20px;
            border: 3px solid rgba(255,255,255,.3);
            border-radius: 50%;
            border-top-color: #fff;
            animation: spin 1s ease-in-out infinite;
        }
        
        @keyframes spin {
            to { transform: rotate(360deg); }
        }
        
        @media (max-width: 768px) {
            .converter-box {
                padding: 20px;
            }
            
            .upload-area {
                padding: 30px 20px;
            }
            
            .controls {
                grid-template-columns: 1fr;
            }
            
            .buttons {
                flex-direction: column;
            }
            
            .btn {
                min-width: 100%;
            }
            
            h1 {
                font-size: 2.2rem;
            }
        }