body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,sans-serif;margin:0;padding:0;line-height:1.6;color:#333;background-color:#f4f7f6}.container{width:90%;max-width:1100px;margin:auto;overflow:hidden;padding:0 20px}.app-header{background:#333;color:#fff;padding:1rem 0;position:sticky;top:0;z-index:1000;box-shadow:0 2px 5px #0000001a}.app-header .container{display:flex;justify-content:space-between;align-items:center}.app-header .logo{font-size:1.5rem;font-weight:700;text-decoration:none;color:#fff}.app-header nav ul{list-style:none;padding:0;margin:0;display:flex}.app-header nav ul li{margin-left:20px}.app-header nav ul li a{color:#fff;text-decoration:none;transition:color .3s ease}.app-header nav ul li a:hover{color:#4caf50}.hero-section{background:#4caf50;color:#fff;padding:60px 0;text-align:center;display:flex;align-items:center;min-height:70vh}.hero-section .container{display:flex;flex-direction:column;align-items:center;justify-content:center}.hero-section .hero-content{max-width:700px}.hero-section h1{font-size:3rem;margin-bottom:20px;line-height:1.2}.hero-section p{font-size:1.2rem;margin-bottom:30px}.hero-section .cta-button{display:inline-block;background:#fff;color:#4caf50;padding:15px 30px;text-decoration:none;font-size:1.1rem;line-height:normal;border-radius:5px;transition:background-color .3s ease,color .3s ease;border:2px solid #fff}.hero-section .cta-button:hover{background:#3e8e41;color:#fff}.hero-section .hero-image{display:block;width:100px;max-width:100%;height:auto;margin-top:40px;margin-left:auto;margin-right:auto;border-radius:8px;box-shadow:0 4px 15px #0000001a}.features-section{padding:60px 0;background-color:#fff}.features-section h2{text-align:center;margin-bottom:40px;font-size:2.5rem;color:#333}.features-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:30px}.feature-item{background:#f9f9f9;padding:25px;border-radius:8px;text-align:center;box-shadow:0 2px 10px #00000014;transition:transform .3s ease,box-shadow .3s ease}.feature-item:hover{transform:translateY(-5px);box-shadow:0 5px 15px #0000001f}.feature-item .icon{font-size:2.5rem;color:#4caf50;margin-bottom:15px}.feature-item h3{font-size:1.5rem;margin-bottom:10px;color:#333}.feature-item p{font-size:1rem;color:#555}.download-section{padding:60px 0;background-color:#f4f7f6}.download-section h2{text-align:center;margin-bottom:50px;font-size:2.5rem;color:#333}.download-platforms{display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:30px;justify-content:center}.download-platform-card{background:#fff;border-radius:8px;padding:25px;text-align:center;box-shadow:0 4px 15px #0000001a;display:flex;flex-direction:column;align-items:center;transition:transform .3s ease,box-shadow .3s ease;position:relative}.download-platform-card:hover{transform:translateY(-5px);box-shadow:0 6px 20px #00000026}.platform-icon-big{font-size:3rem;color:#4caf50;margin-bottom:15px}.download-platform-card h3{font-size:1.5rem;color:#333;margin-bottom:8px}.platform-version{font-size:.9rem;color:#777;margin-bottom:8px}.platform-description{font-size:1rem;color:#555;margin-bottom:20px;flex-grow:1}.download-button{background:#4caf50;color:#fff;padding:12px 25px;text-decoration:none;font-size:1rem;border-radius:5px;transition:background-color .3s ease;display:inline-block}.download-button:hover{background:#3e8e41}.download-button.disabled{background-color:#ccc!important;color:#666!important;cursor:not-allowed!important;opacity:.7}.download-button.disabled:hover{background-color:#ccc!important;color:#666!important;transform:none!important}.app-footer{background:#333;color:#aaa;text-align:center;padding:25px 20px;margin-top:60px;font-size:.9rem}.app-footer .copyright-text{margin:0 0 8px;line-height:1.6}.app-footer .备案-info{margin-top:8px;line-height:1.6}.app-footer .备案-info a{color:#aaa;text-decoration:none;margin:0 8px;display:inline-block}.app-footer .备案-info a:hover{color:#fff;text-decoration:underline}.app-footer .备案-separator{color:#666;margin:0 2px;font-size:.8em;vertical-align:middle}@media (max-width: 1200px){.app-header .container{flex-direction:column}.app-header nav ul{margin-top:10px}.app-header nav ul li{margin:0 10px}.hero-section h1{font-size:2.2rem}.hero-section p{font-size:1rem}.hero-section .hero-image{margin-top:20px;margin-bottom:15px}.features-grid{grid-template-columns:1fr}.download-platforms{flex-direction:column;align-items:center}.download-button{margin-bottom:10px}}.feature-group-title{text-align:center;padding:50px 0 0;background-color:#fff}.feature-group-title h2{font-size:2.8rem;font-weight:600;color:#333;margin-bottom:10px}.feature-group-title h2:after{content:"";display:block;width:80px;height:4px;background-color:#4caf50;margin:15px auto 0;border-radius:2px}.showcase-section{padding:80px 0;overflow:hidden}.showcase-section.bg-light{background-color:#f8f9fa}.showcase-section.bg-white{background-color:#fff}.showcase-content-wrapper{display:flex;align-items:center;gap:50px}.showcase-image-container,.showcase-text-container{flex:1;min-width:0}.showcase-section.layout-image-right .showcase-image-container{order:2;flex:1;min-width:0;display:flex;justify-content:center;align-items:center;height:350px;max-width:550px}.showcase-section.layout-image-right .showcase-text-container{order:1}.showcase-image{border-radius:12px;box-shadow:0 8px 25px #0000001a;display:block;max-width:550px;max-height:350px;width:auto;height:auto;object-fit:initial}.showcase-text-container{padding:20px}.showcase-title{font-size:2.5rem;font-weight:600;color:#333;margin-bottom:15px;line-height:1.3}.showcase-subtitle{font-size:1.3rem;color:#555;margin-bottom:20px;font-weight:400}.showcase-description{font-size:1.1rem;color:#666;line-height:1.8;margin-bottom:25px}.showcase-description p{margin-bottom:1em}.showcase-description p:last-child{margin-bottom:0}.showcase-cta-button{display:inline-block;background-color:#4caf50;color:#fff;padding:12px 28px;border-radius:5px;text-decoration:none;font-size:1rem;font-weight:500;transition:background-color .3s ease,transform .2s ease;box-shadow:0 4px 10px #4caf5066}.showcase-cta-button:hover{background-color:#3e8e41;transform:translateY(-2px)}@media (max-width: 992px){.showcase-content-wrapper{gap:30px}.showcase-title{font-size:2.2rem}.showcase-subtitle{font-size:1.2rem}}@media (max-width: 1200px){.feature-group-title h2{font-size:2.2rem}.showcase-section{padding:50px 0}.showcase-content-wrapper{flex-direction:column;text-align:center}.showcase-section.layout-image-left .showcase-image-container,.showcase-section.layout-image-right .showcase-image-container{order:1;margin-bottom:30px;height:auto;max-width:100%}.showcase-section.layout-image-left .showcase-text-container,.showcase-section.layout-image-right .showcase-text-container{order:2}.showcase-image{width:80%;max-width:400px;height:auto;object-fit:initial;margin-left:auto;margin-right:auto}.showcase-text-container{order:2;padding:0 15px;text-align:center}.showcase-title{font-size:2rem}.showcase-subtitle{font-size:1.1rem}.showcase-description{font-size:1rem}}.qr-code-inline-display{position:absolute;left:50%;transform:translate(-50%);bottom:75px;background-color:#fff;padding:15px;border-radius:8px;box-shadow:0 6px 18px #0003;z-index:10;width:auto;min-width:170px;max-width:90%;text-align:center;opacity:0;visibility:hidden;transform:translate(-50%) translateY(10px);transition:opacity .2s ease,visibility .2s ease,transform .2s ease}.download-platform-card div:not([style*="display: none;"])+.qr-code-inline-display,.download-platform-card .qr-code-inline-display:not([style*="display: none;"]){opacity:1;visibility:visible;transform:translate(-50%) translateY(0)}.qr-code-image-inline{display:block;width:140px;height:140px;margin:0 auto 10px;border:1px solid #f0f0f0}.qr-code-caption{font-size:.85rem;color:#444;margin:0}@media (max-width: 1200px){.qr-code-inline-display{position:absolute;left:50%;transform:translate(-50%);bottom:85px;background-color:#fff;padding:15px;border-radius:8px;box-shadow:0 6px 18px #0003;z-index:10;width:auto;min-width:170px;max-width:90%;text-align:center;opacity:0;visibility:hidden;transform:translate(-50%) translateY(10px);transition:opacity .2s ease,visibility .2s ease,transform .2s ease}}@media (max-width: 480px){.download-platform-card{margin-bottom:0}.qr-code-inline-display{padding:15px}.qr-code-image-inline{width:120px;height:120px}}#student-intro,#teacher-intro,#knowledge-graph,#data-statistics,#download,.showcase-section,.download-section{scroll-margin-top:50px!important}