.hero {
                background: linear-gradient(135deg, #e8f5e9 0%, #f1f8f4 100%);
                padding: 80px 5% 60px;
                text-align: center;
            }
            .hero h1 {
                font-size: 36px;
                color: #2e7d32;
                margin-bottom: 20px;
                max-width: 1200px;
                margin-left: auto;
                margin-right: auto;
            }

            .container {
                max-width: 1200px;
                margin: 0 auto;
                padding: 60px 5%;
            }
            .section {
                margin-bottom: 80px;
            }
            .section-title {
                font-size: 28px;
                color: #2e7d32;
                margin-bottom: 30px;
                padding-bottom: 15px;
                border-bottom: 3px solid #4caf50;
            }

            .overview-grid {
                display: grid;
                grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
                gap: 30px;
                margin-bottom: 40px;
            }
            .overview-card {
                background: white;
                padding: 30px;
                border-radius: 12px;
                box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
            }
            .overview-card h3 {
                font-size: 18px;
                color: #2e7d32;
                margin-bottom: 15px;
                display: flex;
                align-items: center;
                gap: 10px;
            }
            .overview-card p {
                color: #555;
                line-height: 1.8;
            }
            .icon {
                width: 24px;
                height: 24px;
                color: #4caf50;
            }

            .case-title-section {
                margin-bottom: 60px;
            }
            .case-title-card {
                background: white;
                padding: 40px;
                border-radius: 12px;
                box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
                text-align: center;
            }
            .case-badge {
                display: inline-block;
                background: linear-gradient(135deg, #4caf50 0%, #66bb6a 100%);
                color: white;
                padding: 8px 20px;
                border-radius: 20px;
                font-size: 13px;
                font-weight: 600;
                margin-bottom: 20px;
            }
            .case-title-card h2 {
                font-size: 32px;
                color: #2e7d32;
                margin-bottom: 25px;
                font-weight: 700;
            }
            .case-meta-info {
                display: flex;
                gap: 30px;
                justify-content: center;
                flex-wrap: wrap;
            }
            .meta-item {
                display: flex;
                align-items: center;
                gap: 8px;
                color: #666;
                font-size: 14px;
            }
            .meta-item svg {
                color: #4caf50;
            }

            .challenge-solution-section {
                margin-bottom: 40px;
            }
            .challenge-image-container {
                background: white;
                padding: 40px;
                border-radius: 12px;
                box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
                margin-bottom: 50px;
            }
            .challenge-image-container h3 {
                font-size: 24px;
                color: #ff9800;
                margin-bottom: 25px;
                display: flex;
                align-items: center;
                gap: 12px;
            }

            .challenge-cards-grid {
                display: grid;
                grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
                gap: 20px;
            }
            .challenge-item-card {
                background: #fff8f0;
                border: 2px solid #ffe0b2;
                border-radius: 12px;
                padding: 24px;
                display: flex;
                gap: 14px;
                align-items: flex-start;
                transition: transform 0.2s;
            }
            .challenge-item-card:hover {
                transform: translateY(-3px);
            }
            .challenge-num {
                width: 32px;
                height: 32px;
                background: #ff9800;
                color: white;
                border-radius: 50%;
                display: flex;
                align-items: center;
                justify-content: center;
                font-weight: bold;
                font-size: 15px;
                flex-shrink: 0;
            }
            .challenge-item-card p {
                color: #555;
                font-size: 14px;
                line-height: 1.7;
            }
            .challenge-item-card strong {
                display: block;
                color: #e65100;
                margin-bottom: 6px;
                font-size: 15px;
            }

            .solution-detailed {
                background: white;
                padding: 40px;
                border-radius: 12px;
                box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
            }
            .solution-detailed h3 {
                font-size: 24px;
                color: #2e7d32;
                margin-bottom: 40px;
                display: flex;
                align-items: center;
                gap: 12px;
            }
            .solution-timeline {
                position: relative;
                padding-left: 50px;
            }
            .solution-timeline::before {
                content: "";
                position: absolute;
                left: 20px;
                top: 0;
                height: calc(100% - 55px);
                width: 3px;
                background: linear-gradient(180deg, #4caf50 0%, #81c784 100%);
            }
            .timeline-item {
                position: relative;
                margin-bottom: 35px;
                padding-bottom: 35px;
                border-bottom: 1px solid #f0f0f0;
            }
            .timeline-item:last-child {
                border-bottom: none;
                margin-bottom: 0;
                padding-bottom: 0;
            }
            .timeline-number {
                position: absolute;
                left: -50px;
                top: 0;
                width: 40px;
                height: 40px;
                background: linear-gradient(135deg, #4caf50 0%, #66bb6a 100%);
                border-radius: 50%;
                display: flex;
                align-items: center;
                justify-content: center;
                color: white;
                font-weight: bold;
                font-size: 16px;
                box-shadow: 0 4px 10px rgba(76, 175, 80, 0.3);
            }
            .timeline-content h4 {
                color: #2e7d32;
                font-size: 17px;
                margin-bottom: 12px;
                font-weight: 600;
            }
            .timeline-content p {
                color: #555;
                line-height: 1.8;
                font-size: 14px;
            }

            .system-diagram {
                background: white;
                padding: 40px;
                border-radius: 12px;
                box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
                margin-bottom: 40px;
            }
            .diagram-visual-container {
                background: linear-gradient(135deg, #f5f5f5 0%, #e8f5e9 100%);
                padding: 50px 30px;
                border-radius: 12px;
                margin-top: 25px;
            }
            .diagram-layout {
                display: grid;
                grid-template-columns: 1fr auto 1fr;
                gap: 30px;
                max-width: 900px;
                margin: 0 auto;
                align-items: center;
            }

            .iphone-mock {
                background: white;
                border-radius: 12px;
                padding: 30px;
                box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
                text-align: center;
            }
            .iphone-mock h4 {
                color: #2e7d32;
                font-size: 16px;
                margin-bottom: 20px;
            }
            .phone-frame {
                width: 200px;
                height: 150px;
                background: #1a1a2e;
                border-radius: 14px;
                margin: 0 auto 15px;
                display: flex;
                align-items: center;
                justify-content: center;
                box-shadow: 0 8px 20px rgba(0, 0, 0, 0.3);
                position: relative;
            }
            .phone-frame::after {
                content: "";
                position: absolute;
                right: -10px;
                top: 50%;
                transform: translateY(-50%);
                width: 4px;
                height: 30px;
                background: #2a2a3e;
                border-radius: 2px;
            }
            .phone-screen {
                width: 178px;
                height: 128px;
                background: linear-gradient(160deg, #e8f5e9 0%, #c8e6c9 100%);
                border-radius: 8px;
                display: flex;
                flex-direction: column;
                align-items: center;
                justify-content: center;
                gap: 8px;
                padding: 12px;
            }
            .screen-line {
                width: 80%;
                height: 8px;
                background: #4caf50;
                border-radius: 4px;
                opacity: 0.7;
            }
            .screen-line.short {
                width: 55%;
                opacity: 0.4;
            }
            .screen-line.medium {
                width: 70%;
                opacity: 0.55;
            }
            .screen-icon {
                width: 32px;
                height: 32px;
                background: #4caf50;
                border-radius: 6px;
                display: flex;
                align-items: center;
                justify-content: center;
                margin-bottom: 2px;
            }
            .screen-icon svg {
                width: 20px;
                height: 20px;
                color: white;
            }
            .phone-label {
                font-size: 12px;
                color: #666;
                margin-top: 5px;
            }

            .arrow-center {
                display: flex;
                flex-direction: column;
                align-items: center;
                gap: 10px;
            }
            .arrow-box {
                background: white;
                padding: 10px 16px;
                border-radius: 20px;
                font-size: 12px;
                color: #555;
                box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
                white-space: nowrap;
            }
            .arrow-icon {
                font-size: 22px;
                color: #4caf50;
                font-weight: bold;
            }

            .server-side {
                background: white;
                border-radius: 12px;
                padding: 30px;
                box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
            }
            .server-side h4 {
                color: #2e7d32;
                font-size: 16px;
                margin-bottom: 20px;
                text-align: center;
            }
            .server-box {
                background: linear-gradient(135deg, #2196f3 0%, #1976d2 100%);
                color: white;
                padding: 20px;
                border-radius: 10px;
                margin-bottom: 15px;
                text-align: center;
                box-shadow: 0 4px 10px rgba(33, 150, 243, 0.3);
            }
            .server-box h5 {
                font-size: 14px;
                margin-bottom: 6px;
                opacity: 0.9;
            }
            .server-box p {
                font-size: 12px;
                opacity: 0.8;
            }
            .database-box {
                background: linear-gradient(135deg, #4caf50 0%, #45a049 100%);
                color: white;
                padding: 20px;
                border-radius: 8px;
                text-align: center;
                box-shadow: 0 4px 10px rgba(76, 175, 80, 0.3);
            }
            .database-box svg {
                width: 36px;
                height: 36px;
                margin-bottom: 8px;
            }
            .database-box p {
                font-size: 13px;
                margin: 0;
            }

            .system-screens {
                display: flex;
                flex-direction: column;
                gap: 40px;
            }
            .screen-card {
                background: white;
                border-radius: 12px;
                overflow: hidden;
                box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
                transition: all 0.3s;
            }
            .screen-card:hover {
                transform: translateY(-5px);
                box-shadow: 0 8px 30px rgba(0, 0, 0, 0.12);
            }
            .screen-image {
                width: 100%;
                background: #f5f5f5;
                padding: 30px 20px;
                display: flex;
                justify-content: center;
                align-items: center;
                min-height: 300px;
            }
            .screen-image img {
                max-width: 100%;
                height: auto;
                border-radius: 8px;
                box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
            }
            .screen-placeholder {
                width: 100%;
                max-width: 560px;
                height: 280px;
                background: linear-gradient(135deg, #e8f5e9 0%, #f1f8f4 100%);
                border-radius: 12px;
                border: 2px dashed #a5d6a7;
                display: flex;
                flex-direction: column;
                align-items: center;
                justify-content: center;
                gap: 12px;
                color: #66bb6a;
            }
            .screen-placeholder svg {
                width: 48px;
                height: 48px;
                opacity: 0.6;
            }
            .screen-placeholder p {
                font-size: 14px;
                opacity: 0.7;
            }
            .screen-info {
                padding: 30px;
                background: white;
            }
            .screen-info h3 {
                font-size: 20px;
                color: #2e7d32;
                margin-bottom: 12px;
            }
            .screen-info p {
                color: #666;
                line-height: 1.8;
                font-size: 15px;
            }

            .tech-stack {
                display: grid;
                grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
                gap: 20px;
            }
            .tech-category {
                background: white;
                padding: 25px;
                border-radius: 12px;
                box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
            }
            .tech-category h4 {
                font-size: 16px;
                color: #2e7d32;
                margin-bottom: 15px;
                font-weight: bold;
            }
            .tech-tags {
                display: flex;
                flex-wrap: wrap;
                gap: 8px;
            }
            .tech-tag {
                background: #e8f5e9;
                color: #2e7d32;
                padding: 6px 14px;
                border-radius: 20px;
                font-size: 13px;
                font-weight: 500;
            }

            .cta-section {
                background: linear-gradient(135deg, #e8f5e9 0%, #f1f8f4 100%);
                padding: 60px 5%;
                text-align: center;
            }
            .cta-content {
                max-width: 800px;
                margin: 0 auto;
            }
            .cta-section h2 {
                font-size: 32px;
                color: #2e7d32;
                margin-bottom: 20px;
            }
            .cta-section p {
                font-size: 16px;
                color: #555;
                margin-bottom: 30px;
            }
            .cta-buttons {
                display: flex;
                gap: 20px;
                justify-content: center;
                flex-wrap: wrap;
            }
            .btn {
                padding: 15px 40px;
                border-radius: 30px;
                text-decoration: none;
                font-weight: bold;
                font-size: 16px;
                transition: all 0.3s;
                display: inline-block;
            }
            .btn-primary {
                background: #4caf50;
                color: white;
            }
            .btn-primary:hover {
                background: #45a049;
                transform: translateY(-2px);
                box-shadow: 0 6px 20px rgba(76, 175, 80, 0.3);
            }
            .btn-secondary {
                background: white;
                color: #4caf50;
                border: 2px solid #4caf50;
            }
            .btn-secondary:hover {
                background: #4caf50;
                color: white;
            }

@media (max-width: 968px) {
                .overview-grid {
                    grid-template-columns: 1fr;
                }
                .challenge-cards-grid {
                    grid-template-columns: 1fr;
                }
                .card-content {
                    grid-template-columns: 1fr;
                }
                .case-title-card {
                    padding: 28px 20px;
                }
            }

            @media (max-width: 768px) {
                nav {
                    padding: 14px 20px;
                }
                .logo img {
                    max-width: 120px;
                    margin-right: 10px;
                }
                .team-name {
                    font-size: 18px;
                }
                .nav-links {
                    display: none;
                }
                .hamburger {
                    display: flex;
                }
                .hero {
                    padding: 50px 5% 40px;
                }
                .hero h1 {
                    font-size: clamp(20px, 5vw, 28px);
                }
                .container {
                    padding: 24px 4%;
                }
                .section {
                    margin-bottom: 28px;
                }
                .section-title {
                    font-size: 22px;
                }
                .case-title-card h2 {
                    font-size: 22px;
                }
                .solution-timeline {
                    padding-left: 44px;
                }
                .solution-timeline::before {
                    left: 15px;
                    top: 0;
                }
                .timeline-number {
                    left: -44px;
                    width: 30px;
                    height: 30px;
                    font-size: 14px;
                }
                .challenge-image-container,
                .solution-detailed {
                    padding: 20px 16px;
                }
                .challenge-image-container h3 {
                    font-size: 16px;
                    gap: 8px;
                }
                .solution-detailed h3 {
                    font-size: 18px;
                }
                .challenge-item-card strong {
                    font-size: 13px;
                }
                .challenge-item-card p {
                    font-size: 12.5px;
                }

                /* システム構成図：はみ出し防止 */
                .system-diagram {
                    padding: 20px 16px;
                    overflow: hidden;
                }
                .diagram-visual-container {
                    padding: 24px 12px;
                    overflow-x: auto;
                }
                .diagram-layout {
                    grid-template-columns: 1fr;
                    gap: 16px;
                    min-width: 0;
                }
                .iphone-mock {
                    padding: 16px;
                    max-width: 280px;
                    margin: 0 auto;
                }
                .phone-frame {
                    width: 160px;
                    height: 120px;
                    margin: 0 auto 12px;
                }
                .phone-screen {
                    width: 142px;
                    height: 102px;
                }
                .diagram-arrow {
                    transform: rotate(90deg);
                    margin: 0 auto;
                    display: flex;
                    justify-content: center;
                }
                .cta-section {
                    padding: 40px 5%;
                }
                .cta-section h2 {
                    font-size: 22px;
                }
                .cta-section p {
                    font-size: 14px;
                }
                .cta-buttons {
                    flex-direction: column;
                    align-items: stretch;
                }
                .btn {
                    width: 100%;
                    text-align: center;
                    padding: 14px 24px;
                    font-size: 15px;
                }
                .tech-stack {
                    grid-template-columns: repeat(2, 1fr);
                }
                .breadcrumb {
                    font-size: 12px;
                }
                .hero-meta {
                    gap: 12px;
                    font-size: 13px;
                }
                .case-meta-info {
                    gap: 12px;
                }
                .screen-card {
                    grid-template-columns: 1fr;
                }
            }

            @media (max-width: 480px) {
                .tech-stack {
                    grid-template-columns: 1fr;
                }
                .solution-timeline {
                    padding-left: 38px;
                }
                .solution-timeline::before {
                    left: 13px;
                    top: 0;
                }
                .timeline-number {
                    left: -38px;
                    width: 26px;
                    height: 26px;
                    font-size: 12px;
                }
                .case-title-card h2 {
                    font-size: 18px;
                }
            }