:root {
            --bg-main: #0b0f19; --bg-panel: #111827; --bg-card: #1f2937;
            --text-light: #f8fafc; --text-muted: #94a3b8;
            --accent-brand: #8b5cf6; --accent-local: #3b82f6; --accent-cloud: #10b981;
            --success: #10b981; --error: #ef4444; --border-color: #334155;
        }
        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
            background-color: var(--bg-main); color: var(--text-light); margin: 0; display: flex; min-height: 100vh; font-weight: 400; font-size: 16px;
        }

        .icon { width: 22px; height: 22px; fill: none; stroke: currentColor; stroke-width: 1.5; stroke-linecap: round; stroke-linejoin: round; }
        .icon-large { width: 44px; height: 44px; stroke-width: 1; }

        .sidebar {
            width: 280px; background-color: var(--bg-panel); border-right: 1px solid var(--border-color);
            padding: 30px 20px; display: flex; flex-direction: column; position: fixed; height: 100vh; box-sizing: border-box;
        }
        .logo { font-size: 24px; font-weight: 300; color: #fff; margin-bottom: 40px; letter-spacing: 0.5px; }
        .logo span { font-weight: 600; color: var(--accent-local); }
        .nav-item {
            padding: 14px 16px; border-radius: 8px; color: var(--text-muted); text-decoration: none; 
            font-size: 17px; font-weight: 400; display: flex; align-items: center; gap: 12px; transition: 0.2s; margin-bottom: 6px;
        }
        .nav-item:hover, .nav-item.active { background: rgba(59, 130, 246, 0.05); color: var(--accent-local); }

        .main-content { margin-left: 280px; padding: 40px 60px; flex-grow: 1; box-sizing: border-box; max-width: 1000px; }
        
        .header-title { display: flex; align-items: center; gap: 15px; margin-bottom: 10px; }
        .header-title h1 { margin: 0; font-size: 36px; font-weight: 300; letter-spacing: -0.5px; }
        .badge { background: rgba(59, 130, 246, 0.1); border: 1px solid rgba(59, 130, 246, 0.2); color: var(--accent-local); padding: 5px 12px; border-radius: 6px; font-size: 14px; font-weight: 500; }
        .subtitle { color: var(--text-muted); font-size: 18px; margin-bottom: 45px; line-height: 1.7; font-weight: 300; }

        .drop-zone {
            background: var(--bg-card); border: 1px dashed var(--border-color); border-radius: 12px; padding: 70px 20px;
            text-align: center; cursor: pointer; transition: all 0.2s ease; margin-bottom: 35px;
        }
        .drop-zone.dragover { border-color: var(--accent-local); background: rgba(59, 130, 246, 0.02); }
        .drop-icon { color: var(--text-muted); margin-bottom: 15px; display: inline-block; }
        .drop-text { font-size: 18px; font-weight: 500; color: var(--text-light); margin-bottom: 10px; }
        .drop-hint { font-size: 15px; color: var(--text-muted); font-weight: 300; }
        #fileInput { display: none; }

        .settings-panel { margin-bottom: 35px; }
        .settings-title { font-size: 15px; font-weight: 500; margin-bottom: 15px; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.5px; }
        .format-group { display: flex; flex-wrap: wrap; gap: 10px; }
        .format-group label { cursor: pointer; flex-grow: 1; text-align: center; }
        .format-group input[type="radio"] { display: none; }
        .format-group span { 
            display: block; padding: 12px 18px; border-radius: 8px; background: var(--bg-panel); 
            color: var(--text-muted); font-weight: 400; font-size: 16px; transition: 0.2s; border: 1px solid var(--border-color); 
        }
        .format-group input[type="radio"]:checked + span { 
            background: rgba(59, 130, 246, 0.05); color: var(--accent-local); border-color: var(--accent-local); 
        }
        
        .server-hint {
            display: none; margin-top: 15px; padding: 15px 18px; background: rgba(16, 185, 129, 0.05); 
            border: 1px solid rgba(16, 185, 129, 0.2); border-radius: 8px; color: var(--text-muted); font-size: 15px; line-height: 1.6;
        }

        .btn-convert {
            background: var(--accent-local); color: white; border: none; padding: 16px; border-radius: 8px;
            font-size: 17px; font-weight: 500; width: 100%; cursor: pointer; transition: 0.2s; letter-spacing: 0.5px;
        }
        .btn-convert:hover { background: #2563eb; }
        .btn-convert:disabled { background: var(--bg-panel); border: 1px solid var(--border-color); cursor: not-allowed; color: var(--text-muted); }
        
        .btn-redirect { background: var(--accent-cloud); }
        .btn-redirect:hover { background: #059669; }

        .file-list { margin-top: 35px; display: flex; flex-direction: column; gap: 10px; }
        .file-item { 
            background: var(--bg-panel); padding: 15px 20px; border-radius: 8px; border: 1px solid var(--border-color);
            display: flex; justify-content: space-between; align-items: center;
        }
        .file-info { display: flex; align-items: center; gap: 15px; }
        .file-name { font-weight: 400; font-size: 16px; word-break: break-all; color: var(--text-light); }
        .file-size { color: var(--text-muted); font-size: 14px; font-weight: 300; }
        .file-status { font-size: 15px; font-weight: 400; color: var(--text-muted); }
        
        .dl-btn {
            background: transparent; color: var(--success); border: 1px solid var(--success); text-decoration: none; padding: 8px 14px;
            border-radius: 6px; font-size: 14px; font-weight: 500; transition: 0.2s; display: flex; align-items: center; gap: 8px;
        }
        .dl-btn:hover { background: rgba(16, 185, 129, 0.1); }

        @media (max-width: 900px) {
            body { flex-direction: column; }
            .sidebar { width: 100%; height: auto; position: static; padding: 20px; flex-direction: row; justify-content: space-between; align-items: center; border-right: none; border-bottom: 1px solid var(--border-color); }
            .nav-item { display: none; } 
            .nav-item.active { display: flex; margin: 0; padding: 10px 14px; font-size: 16px; }
            .main-content { margin-left: 0; padding: 30px 20px; }
            .header-title h1 { font-size: 26px; }
            .drop-zone { padding: 40px 15px; }
        }