.shape-selector {
            display: flex;
            flex-wrap: wrap;
            gap: 0.75rem;
            margin: 1.25rem 0 1.5rem 0;
        }
        .shape-btn {
            background: #f8f9fa;
            border: 2px solid #dee2e6;
            border-radius: 10px;
            padding: 0.6rem 1.25rem;
            font-weight: 500;
            color: #495057;
            cursor: pointer;
            transition: all 0.2s ease;
            display: flex;
            align-items: center;
            gap: 0.5rem;
            font-size: 0.95rem;
        }
        .shape-btn:hover {
            background: #e9ecef;
            transform: translateY(-2px);
            box-shadow: 0 4px 8px rgba(0,0,0,0.06);
        }
        .shape-btn.active {
            background: var(--primary-color, #0d6efd);
            border-color: var(--primary-color, #0d6efd);
            color: #fff;
        }
        .shape-btn i {
            font-size: 1.1rem;
        }
        .dimension-group {
            background: #f8fafc;
            border-radius: 10px;
            padding: 1.25rem 1.5rem;
            margin: 1rem 0 1.25rem 0;
            border: 1px solid #e9ecef;
        }
        .dimension-group label {
            font-weight: 500;
            color: #1a2634;
            margin-bottom: 0.3rem;
        }
        .dimension-group .form-text {
            font-size: 0.8rem;
        }
        .result-number {
            font-size: 2.8rem;
            font-weight: 700;
            color: var(--primary-color, #0d6efd);
            line-height: 1.2;
        }
        .result-number small {
            font-size: 1.1rem;
            font-weight: 400;
            color: #6c757d;
        }
        .unit-toggle {
            display: inline-flex;
            background: #f1f3f5;
            border-radius: 30px;
            padding: 0.2rem;
            margin: 0.5rem 0;
        }
        .unit-toggle button {
            border: none;
            background: transparent;
            padding: 0.3rem 1rem;
            border-radius: 30px;
            font-weight: 500;
            font-size: 0.85rem;
            color: #6c757d;
            transition: all 0.2s;
        }
        .unit-toggle button.active {
            background: #fff;
            color: #1a2634;
            box-shadow: 0 2px 8px rgba(0,0,0,0.08);
        }
        .unit-toggle button:hover {
            color: #1a2634;
        }
        .result-card {
            background: #fff;
            border-radius: 12px;
            padding: 1.25rem 1.5rem;
            box-shadow: 0 2px 12px rgba(0,0,0,0.04);
            border: 1px solid #e9ecef;
            margin: 0.5rem 0;
        }
        .result-card .label {
            font-size: 0.85rem;
            text-transform: uppercase;
            letter-spacing: 0.4px;
            color: #6c757d;
            font-weight: 600;
        }
        .result-card .value {
            font-size: 1.6rem;
            font-weight: 600;
            color: #1a2634;
        }
        .material-estimate {
            background: #f0f7ff;
            border-left: 4px solid var(--primary-color, #0d6efd);
            padding: 1rem 1.25rem;
            border-radius: 0 8px 8px 0;
            margin: 1.25rem 0;
        }
        .material-estimate h6 {
            font-weight: 600;
            color: #1a2634;
        }
        .conversion-table td {
            padding: 0.4rem 0.75rem;
        }
        .conversion-table .unit {
            font-weight: 500;
        }
        .canvas-area {
            width: 100%;
            background: #fafcfe;
            border: 1px solid #dee2e6;
            border-radius: 10px;
            margin-top: 1rem;
            display: block;
        }
        .canvas-container {
            text-align: center;
            margin: 1rem 0;
        }
        .canvas-container canvas {
            width: 100%;
            height: auto;
            max-height: 280px;
            background: #fafcfe;
            border-radius: 8px;
        }
        .legend-shape {
            display: flex;
            justify-content: center;
            gap: 1.5rem;
            flex-wrap: wrap;
            font-size: 0.85rem;
            color: #495057;
            margin: 0.25rem 0 0.5rem 0;
        }
        .legend-shape span {
            display: flex;
            align-items: center;
            gap: 0.4rem;
        }
        .legend-shape .dot {
            width: 12px;
            height: 12px;
            border-radius: 50%;
            display: inline-block;
        }
        .legend-shape .dot.primary { background: var(--primary-color, #0d6efd); }
        .legend-shape .dot.dim { background: #adb5bd; }
        .example-presets {
            display: flex;
            flex-wrap: wrap;
            gap: 0.5rem;
            margin: 0.75rem 0 0.25rem 0;
        }
        .preset-btn {
            background: #f1f3f5;
            border: none;
            border-radius: 20px;
            padding: 0.25rem 0.9rem;
            font-size: 0.8rem;
            color: #495057;
            cursor: pointer;
            transition: all 0.15s;
        }
        .preset-btn:hover {
            background: #dee2e6;
            color: #1a2634;
        }
        .faq-accordion .accordion-button {
            font-weight: 500;
        }
        .faq-accordion .accordion-button:not(.collapsed) {
            background: rgba(13, 110, 253, 0.04);
            color: var(--primary-color, #0d6efd);
        }
        .authority-ref {
            font-size: 0.9rem;
            border-top: 1px solid #e9ecef;
            padding-top: 1rem;
            margin-top: 1.5rem;
            color: #6c757d;
        }
        .authority-ref a {
            color: var(--primary-color, #0d6efd);
            text-decoration: none;
        }
        .authority-ref a:hover {
            text-decoration: underline;
        }
        .shape-icon-lg {
            font-size: 2.2rem;
            color: var(--primary-color, #0d6efd);
            opacity: 0.7;
            margin-right: 0.5rem;
        }
        .tool-header .badge {
            font-size: 0.8rem;
            font-weight: 500;
            padding: 0.4rem 0.8rem;
        }
        @media (max-width: 576px) {
            .result-number {
                font-size: 2rem;
            }
            .shape-btn {
                padding: 0.4rem 0.9rem;
                font-size: 0.85rem;
            }
            .dimension-group {
                padding: 1rem;
            }
        }