/* --- APP UI STYLES (Strictly Grid) --- */
        :root {
            --sidebar-bg: #1e1e26;
            --preview-bg: #f5f7fa;
            --accent: #4a90e2;
            --text-light: #ffffff;
            --border-ui: #3f3f4b;
        }

        * { box-sizing: border-box; margin: 0; padding: 0; }
        body { font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; background: var(--sidebar-bg); color: var(--text-light); }

        #app-architect {
            display: grid;
            grid-template-columns: 400px 1fr;
            height: 100vh;
            overflow: hidden;
        }

        @media(max-width: 780px) {
            #app-architect {
                grid-template-columns: 1fr;
                height: auto; 
            }
        }

        /* Sidebar Architecture */
        #configuration-sidebar {
            display: grid;
            grid-template-rows: auto 1fr auto;
            background: var(--sidebar-bg);
            border-right: 2px solid var(--border-ui);
            padding: 20px;
            overflow-y: auto;
            gap: 20px;
        }

        .section-title { font-size: 0.9rem; text-transform: uppercase; letter-spacing: 1px; color: var(--accent); margin-bottom: 15px; border-bottom: 1px solid var(--border-ui); padding-bottom: 5px; }
        .control-group { display: grid; gap: 10px; margin-bottom: 20px; }
        .grid-2col { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
        .grid-4col { display: grid; grid-template-columns: repeat(4, 1fr); gap: 5px; }

        label { font-size: 0.8rem; color: #a4a4b5; }
        input[type="text"], input[type="number"], select, textarea {
            width: 100%; padding: 8px; background: #2d2d3a; border: 1px solid var(--border-ui); color: white; border-radius: 4px;
        }
        
        .btn-add { background: var(--accent); color: white; border: none; padding: 12px; cursor: pointer; font-weight: bold; width: 100%; border-radius: 4px; }
        .btn-add:hover { background: #357abd; }

        /* Preview Pane Architecture */
        #live-preview-frame {
            display: grid;
            grid-template-rows: 1fr 300px;
            background: var(--border-ui);
            overflow: hidden;
        }

        #canvas {
            display: grid;
            place-items: start center;
            padding: 50px;
            overflow-y: auto;
            background-image: radial-gradient(#ffffff 1px, transparent 1px);
            background-size: 20px 20px;
        }

        /* Code Mirror Area */
        #export-zone {
            background: #282c34;
            padding: 20px;
            display: grid;
            grid-template-rows: auto 1fr auto;
            border-top: 5px solid #4a90e2;
        }

        a {
            float: right;
            margin-top: -5px;
            -webkit-text-decoration: none;
            -moz-text-decoration: none;
            text-decoration: none;
            color: #ffffff;
            font-size: 16px;
            z-index: 10;
        }
        
        #code-display {
            width: 100%;
            height: 100%;
            background: #1e1e1e;
            color: #9cdcfe;
            font-family: 'Courier New', Courier, monospace;
            padding: 15px;
            border: none;
            resize: none;
            font-size: 0.85rem;
        }

        .export-actions {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 15px;
            padding-top: 15px;
        }

        .btn-export { padding: 10px; cursor: pointer; border: none; font-weight: bold; border-radius: 4px; }
        .btn-copy { background: #4caf50; color: white; }
        .btn-download { background: #ff9800; color: white; }

        /* Tooltip style */
        .tooltip { position: relative; }
        .tooltip::after {
            content: "Copied!"; position: absolute; top: -40px; left: 50%; transform: translateX(-50%);
            background: #333; padding: 5px 10px; border-radius: 4px; opacity: 0; transition: 0.3s; pointer-events: none;
        }
        .tooltip.show::after { opacity: 1; }

        /* Item Entry Cards in Sidebar */
        .item-entry {
            background: #2d2d3a; padding: 15px; border-radius: 6px; border-left: 4px solid var(--accent); margin-bottom: 10px;
            display: grid; gap: 8px;
        }
        .remove-item { color: #ff5f56; cursor: pointer; font-size: 0.7rem; text-align: right; text-decoration: underline; }