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#0000000d;margin-bottom:40px;overflow:hidden;border:1px solid #e1e4e8}.topic-content{flex:1;padding:30px}.topic-content h3{color:#007bff;margin-top:0;font-size:1.5rem}.topic-description{line-height:1.6;color:#555;margin-bottom:20px}.key-points{background-color:#f8f9fa;padding:15px;border-left:4px solid #28a745;border-radius:4px}.key-points h4{margin-top:0;color:#28a745}.key-points ul{padding-left:20px;margin-bottom:0}.video-container{flex:1;background-color:#000;position:relative;min-height:300px}.video-responsive{width:100%;height:100%;border:none}@media(max-width:900px){.topic-card{flex-direction:column}.video-container{height:300px;width:100%}}#root,.app-container{min-height:100vh;display:flex;flex-direction:column}.main-content{flex:1}