* { margin: 0; padding: 0; box-sizing: border-box; font-family: 'Segoe UI', Roboto, system-ui, sans-serif; }
        body {
            background: linear-gradient(145deg, #1e2b5e 0%, #2d1b4e 100%);
            min-height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            padding: 20px;
        }
        .container {
            max-width: 1300px;
            width: 100%;
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(8px);
            border-radius: 40px;
            box-shadow: 0 30px 70px rgba(0, 0, 0, 0.5);
            overflow: hidden;
        }
        .header {
            background: linear-gradient(135deg, #3a2b7c, #5e2a9c);
            color: white;
            padding: 30px 35px;
            text-align: center;
        }
        .header .logo {
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 15px;
            font-size: 2rem;
            font-weight: 600;
        }
        .header .logo i { font-size: 3rem; filter: drop-shadow(0 4px 6px #00000033); }
        .subtitle { opacity: 0.9; font-size: 1.1rem; margin-top: 8px; }

        .main-content {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 30px;
            padding: 35px;
        }
        @media (max-width: 900px) { .main-content { grid-template-columns: 1fr; } }

        /* upload & preview cards */
        .upload-section, .preview-section {
            background: #ffffffdd;
            border-radius: 28px;
            padding: 28px;
            box-shadow: 0 8px 20px rgba(0, 0, 0, 0.08);
            border: 1px solid #ffffff80;
        }
        h2 { display: flex; align-items: center; gap: 12px; font-weight: 500; color: #1e1e2f; margin-bottom: 22px; font-size: 1.8rem; }
        h2 i { color: #4f46e5; }

        /* UPLOAD AREA */
        .upload-area {
            border: 3px dashed #a5b4fc;
            border-radius: 30px;
            padding: 45px 25px;
            text-align: center;
            background: #f1f5fe;
            cursor: pointer;
            transition: 0.2s;
            margin-bottom: 25px;
        }
        .upload-area:hover { border-color: #4f46e5; background: #e8edff; transform: scale(1.01); }
        .upload-area i { font-size: 4.5rem; color: #4f46e5; margin-bottom: 15px; }
        .upload-area h3 { font-size: 1.8rem; font-weight: 500; color: #1e293b; }
        .upload-area p { color: #475569; font-size: 1rem; margin: 8px 0; }
        .file-input { display: none; }

        .file-info {
            background: white;
            border-radius: 18px;
            padding: 20px;
            margin: 20px 0 25px;
            border: 1px solid #cbd5e1;
            display: none;
            box-shadow: 0 4px 10px #e2e8f0;
        }
        .file-info.show { display: block; animation: fadeSlide 0.25s; }
        @keyframes fadeSlide { from { opacity: 0; transform: translateY(-8px); } to { opacity: 1; transform: translateY(0); } }
        .file-details {
            display: flex;
            justify-content: space-between;
            font-weight: 600;
            color: #0f172a;
            margin-bottom: 15px;
            font-size: 1.15rem;
        }
        .file-name { color: #2563eb; word-break: break-word; }
        .file-size { background: #dbeafe; padding: 4px 12px; border-radius: 40px; color: #1e40af; }

        .progress-bar {
            height: 8px;
            background: #e2e8f0;
            border-radius: 20px;
            overflow: hidden;
            width: 100%;
        }
        .progress { height: 100%; width: 0%; background: linear-gradient(90deg, #4f46e5, #7c3aed); transition: width 0.3s; }

        .action-buttons {
            display: flex;
            gap: 20px;
            flex-wrap: wrap;
            margin-top: 20px;
        }
        .btn {
            flex: 1 1 200px;
            padding: 16px 10px;
            border: none;
            border-radius: 50px;
            font-size: 1.2rem;
            font-weight: 600;
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 12px;
            cursor: pointer;
            transition: 0.2s;
            text-decoration: none;
            color: white;
        }
        .btn-primary { background: linear-gradient(145deg, #4f46e5, #7c3aed); box-shadow: 0 12px 18px -8px #4f46e5a0; }
        .btn-primary:hover:not(:disabled) { transform: translateY(-3px); box-shadow: 0 20px 25px -8px #4f46e5; }
        .btn-primary:disabled { background: #a5b4fc; opacity: 0.5; cursor: not-allowed; box-shadow: none; }
        .btn-success { background: #059669; box-shadow: 0 8px 18px #05966970; }
        .btn-success:hover:not(:disabled) { background: #047857; transform: scale(1.02); }
        .btn-success:disabled { background: #9ca3af; opacity: 0.5; pointer-events: none; }

        /* PREVIEW + OVERLAY */
        .preview-container {
            background: #f8fafc;
            border-radius: 24px;
            height: 480px;
            position: relative;
            overflow: hidden;
            border: 2px solid #e2e8f0;
            box-shadow: inset 0 4px 10px #0000000c;
        }
        .preview-placeholder {
            height: 100%;
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            color: #94a3b8;
            font-size: 1.2rem;
        }
        .preview-placeholder i { font-size: 5rem; margin-bottom: 20px; color: #a5b4fc; }

        #pdfPreview {
            width: 100%;
            height: 100%;
            border: none;
            background: white;
            display: none;
        }

        /* converting overlay */
        .converting-overlay {
            position: absolute;
            top: 0; left: 0; width: 100%; height: 100%;
            background: rgba(255, 255, 255, 0.96);
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            backdrop-filter: blur(6px);
            z-index: 25;
            display: none;
        }
        .converting-overlay.show { display: flex; }
        .loading-spinner {
            width: 70px; height: 70px;
            border: 6px solid #e0e7ff;
            border-top-color: #4f46e5;
            border-radius: 50%;
            animation: spin 0.9s linear infinite;
            margin-bottom: 30px;
        }
        @keyframes spin { to { transform: rotate(360deg); } }

        /* alerts */
        .alert {
            padding: 16px 25px;
            border-radius: 80px;
            margin: 20px 35px 0;
            display: none;
            align-items: center;
            gap: 15px;
            font-weight: 500;
            box-shadow: 0 6px 14px rgba(0,0,0,0.08);
            animation: slideIn 0.2s;
        }
        .alert.show { display: flex; }
        .alert.error { background: #fee2e2; color: #b91c1c; border-left: 6px solid #dc2626; }
        .alert.success { background: #dcfce7; color: #166534; border-left: 6px solid #16a34a; }

        .footer-note {
            padding: 25px 30px;
            text-align: center;
            background: #1e1b4b10;
            color: #334155;
            border-top: 1px dashed #94a3b8;
        }
        .footer-note strong { color: #4f46e5; }