/* ===== Reset & Base ===== */
        *,
        *::before,
        *::after {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }

        body {
            font-family: 'Roboto', 'Segoe UI', sans-serif;
            background: #ffffff;
            color: #1a1a2e;
            line-height: 1.6;
        }

        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 24px;
        }

        /* ===== E‑Paper & NFC Board Module ===== */
        .board-module {
            padding: 80px 0 100px;
            background: #ffffff;
            position: relative;
        }

        /* ---- Section Header ---- */
        .section-header {
            text-align: center;
            margin-bottom: 60px;
        }

        .section-header .badge {
            display: inline-block;
            background: rgba(42, 92, 170, 0.10);
            color: #2A5CAA;
            font-size: 0.7rem;
            font-weight: 700;
            letter-spacing: 2px;
            text-transform: uppercase;
            padding: 6px 22px;
            border-radius: 30px;
            margin-bottom: 18px;
            border: 1px solid rgba(42, 92, 170, 0.08);
        }

        .section-header h2 {
            font-family: 'Montserrat', sans-serif;
            font-size: 2.6rem;
            font-weight: 800;
            color: #1a1a2e;
            letter-spacing: -0.5px;
            margin-bottom: 16px;
        }

        .section-header h2 span {
            color: #2A5CAA;
            position: relative;
        }

        .section-header h2 span::after {
            content: '';
            position: absolute;
            bottom: 4px;
            left: 0;
            width: 100%;
            height: 8px;
            background: rgba(255, 107, 53, 0.25);
            border-radius: 4px;
            z-index: -1;
        }

        .section-header .subtitle {
            font-size: 1.05rem;
            color: #555;
            max-width: 600px;
            margin: 0 auto;
        }

        /* ===== Formula Layout ===== */
        .formula-container {
            display: flex;
            align-items: center;
            justify-content: center;
            flex-wrap: wrap;
            gap: 12px 20px;
            margin-top: 10px;
        }

        /* ---- Component Cards ---- */
        .component-card {
            background: #ffffff;
            border-radius: 20px;
            padding: 28px 24px 24px;
            box-shadow: 0 8px 32px rgba(0, 0, 0, 0.04);
            border: 1px solid rgba(42, 92, 170, 0.06);
            transition: all 0.4s cubic-bezier(0.25, 0.8, 0.25, 1);
            display: flex;
            flex-direction: column;
            align-items: center;
            text-align: center;
            min-width: 180px;
            max-width: 220px;
            flex: 0 1 auto;
            position: relative;
        }

        .component-card:hover {
            transform: translateY(-6px);
            box-shadow: 0 16px 48px rgba(42, 92, 170, 0.10);
            border-color: rgba(42, 92, 170, 0.12);
        }

        .component-card .card-image {
            width: 100%;
            height: 110px;
            display: flex;
            align-items: center;
            justify-content: center;
            margin-bottom: 16px;
            background: #f8fbff;
            border-radius: 12px;
            padding: 8px;
            transition: all 0.4s ease;
        }

        .component-card:hover .card-image {
            background: #f0f6ff;
        }

        .component-card .card-image img {
            max-width: 100%;
            max-height: 100%;
            object-fit: contain;
            transition: transform 0.4s ease;
        }

        .component-card:hover .card-image img {
            transform: scale(1.04);
        }

        .component-card .card-label {
            font-size: 0.7rem;
            font-weight: 600;
            text-transform: uppercase;
            letter-spacing: 0.8px;
            color: #888;
            margin-bottom: 4px;
        }

        .component-card .card-name {
            font-family: 'Montserrat', sans-serif;
            font-size: 1rem;
            font-weight: 700;
            color: #1a1a2e;
            margin-bottom: 4px;
        }

        .component-card .card-desc {
            font-size: 0.8rem;
            color: #777;
            line-height: 1.4;
        }

        /* ---- Operator Icons ( + and = ) ---- */
        .operator {
            font-family: 'Montserrat', sans-serif;
            font-size: 1.8rem;
            font-weight: 800;
            color: #2A5CAA;
            flex-shrink: 0;
            width: 40px;
            text-align: center;
            opacity: 0.6;
            transition: opacity 0.3s ease;
        }

        .operator.equals {
            font-size: 2.2rem;
            color: #FF6B35;
            opacity: 1;
        }

        .formula-container:hover .operator {
            opacity: 0.9;
        }

        .formula-container:hover .operator.equals {
            opacity: 1;
        }

        /* ---- Result Product Card ---- */
        .result-card {
            background: linear-gradient(135deg, #f0f7ff 0%, #e8f0fe 100%);
            border-radius: 20px;
            padding: 28px 28px 24px;
            border: 2px solid #2A5CAA;
            box-shadow: 0 8px 32px rgba(42, 92, 170, 0.10);
            transition: all 0.4s cubic-bezier(0.25, 0.8, 0.25, 1);
            display: flex;
            flex-direction: column;
            align-items: center;
            text-align: center;
            min-width: 180px;
            max-width: 220px;
            flex: 0 1 auto;
            position: relative;
        }

        .result-card::before {
            content: '✓ Complete Kit';
            position: absolute;
            top: -10px;
            right: -8px;
            background: #FF6B35;
            color: #fff;
            font-size: 0.6rem;
            font-weight: 700;
            letter-spacing: 0.5px;
            text-transform: uppercase;
            padding: 4px 14px;
            border-radius: 20px;
            box-shadow: 0 4px 12px rgba(255, 107, 53, 0.30);
        }

        .result-card:hover {
            transform: translateY(-6px);
            box-shadow: 0 20px 56px rgba(42, 92, 170, 0.18);
        }

        .result-card .card-image {
            width: 100%;
            height: 110px;
            display: flex;
            align-items: center;
            justify-content: center;
            margin-bottom: 16px;
            background: rgba(255, 255, 255, 0.6);
            border-radius: 12px;
            padding: 8px;
            transition: all 0.4s ease;
        }

        .result-card:hover .card-image {
            background: rgba(255, 255, 255, 0.85);
        }

        .result-card .card-image img {
            max-width: 100%;
            max-height: 100%;
            object-fit: contain;
            transition: transform 0.4s ease;
        }

        .result-card:hover .card-image img {
            transform: scale(1.04);
        }

        .result-card .card-label {
            font-size: 0.7rem;
            font-weight: 600;
            text-transform: uppercase;
            letter-spacing: 0.8px;
            color: #2A5CAA;
            margin-bottom: 4px;
        }

        .result-card .card-name {
            font-family: 'Montserrat', sans-serif;
            font-size: 1.2rem;
            font-weight: 800;
            color: #1a1a2e;
            margin-bottom: 2px;
        }

        .result-card .card-desc {
            font-size: 0.8rem;
            color: #555;
            line-height: 1.4;
        }

        /* ---- Bottom Note ---- */
        .formula-note {
            text-align: center;
            margin-top: 40px;
            font-size: 0.9rem;
            color: #777;
            background: #f8faff;
            padding: 14px 24px;
            border-radius: 40px;
            display: inline-block;
            border: 1px solid rgba(42, 92, 170, 0.06);
        }

        .formula-note strong {
            color: #2A5CAA;
            font-weight: 600;
        }

        .note-wrapper {
            text-align: center;
        }

        /* ===== Responsive ===== */
        @media (max-width: 1024px) {
            .section-header h2 {
                font-size: 2.2rem;
            }
            .component-card {
                min-width: 150px;
                max-width: 180px;
                padding: 20px 16px 18px;
            }
            .result-card {
                min-width: 150px;
                max-width: 180px;
                padding: 20px 16px 18px;
            }
            .component-card .card-image,
            .result-card .card-image {
                height: 90px;
            }
            .operator {
                font-size: 1.5rem;
                width: 30px;
            }
            .operator.equals {
                font-size: 1.8rem;
            }
        }

        @media (max-width: 820px) {
            .formula-container {
                gap: 10px 16px;
            }
            .component-card {
                min-width: 130px;
                max-width: 160px;
                padding: 16px 14px 14px;
            }
            .result-card {
                min-width: 130px;
                max-width: 160px;
                padding: 16px 14px 14px;
            }
            .component-card .card-image,
            .result-card .card-image {
                height: 78px;
            }
            .component-card .card-name {
                font-size: 0.85rem;
            }
            .result-card .card-name {
                font-size: 1rem;
            }
            .operator {
                font-size: 1.2rem;
                width: 24px;
            }
            .operator.equals {
                font-size: 1.5rem;
            }
        }

        @media (max-width: 640px) {
            .board-module {
                padding: 60px 0 70px;
            }
            .section-header h2 {
                font-size: 1.8rem;
            }
            .section-header .subtitle {
                font-size: 1rem;
            }

            .formula-container {
                gap: 8px 12px;
                flex-wrap: wrap;
                justify-content: center;
            }
            .component-card {
                min-width: 100px;
                max-width: 130px;
                padding: 14px 10px 12px;
                border-radius: 14px;
            }
            .result-card {
                min-width: 100px;
                max-width: 130px;
                padding: 14px 10px 12px;
                border-radius: 14px;
            }
            .component-card .card-image,
            .result-card .card-image {
                height: 60px;
                border-radius: 8px;
                margin-bottom: 10px;
            }
            .component-card .card-name {
                font-size: 0.7rem;
            }
            .component-card .card-desc {
                font-size: 0.65rem;
            }
            .result-card .card-name {
                font-size: 0.85rem;
            }
            .result-card .card-desc {
                font-size: 0.65rem;
            }
            .component-card .card-label,
            .result-card .card-label {
                font-size: 0.55rem;
                letter-spacing: 0.5px;
            }
            .operator {
                font-size: 1rem;
                width: 18px;
            }
            .operator.equals {
                font-size: 1.2rem;
            }
            .result-card::before {
                font-size: 0.5rem;
                padding: 2px 10px;
                top: -8px;
                right: -4px;
            }
            .formula-note {
                font-size: 0.75rem;
                padding: 10px 18px;
            }
        }

        @media (max-width: 420px) {
            .component-card {
                min-width: 80px;
                max-width: 100px;
                padding: 10px 6px 10px;
                border-radius: 12px;
            }
            .result-card {
                min-width: 80px;
                max-width: 100px;
                padding: 10px 6px 10px;
                border-radius: 12px;
            }
            .component-card .card-image,
            .result-card .card-image {
                height: 48px;
                margin-bottom: 6px;
            }
            .component-card .card-name {
                font-size: 0.6rem;
            }
            .result-card .card-name {
                font-size: 0.7rem;
            }
            .component-card .card-desc,
            .result-card .card-desc {
                font-size: 0.55rem;
            }
            .operator {
                font-size: 0.8rem;
                width: 14px;
            }
            .operator.equals {
                font-size: 1rem;
            }
            .formula-container {
                gap: 4px 6px;
            }
        }