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.image-dimensions{color:#666;font-size:14px}.btn-download{background:#1890ff;color:#fff}.btn-download:hover{background:#40a9ff;transform:translateY(-1px)}.btn-download .icon{filter:brightness(0) invert(1);height:16px;width:16px}.btn-close-preview{background:#6c757d;color:#fff}.btn-close-preview:hover{background:#5a6268;transform:translateY(-1px)}@keyframes fadeIn{0%{opacity:0}to{opacity:1}}@keyframes scaleIn{0%{opacity:0;transform:scale(.9)}to{opacity:1;transform:scale(1)}}.pcBtn{display:block}@media screen and (max-width:920px) and (orientation:landscape){#showTextbooks .tab1{padding:8px}.my-btn,.user-name{font-size:13px}#video-container{min-height:110px}#local-video{height:64px;width:100px}}@media (max-width:520px){#container{height:auto;position:unset}.mobile-chat-backdrop{background:#00000080;top:0;right:0;bottom:0;left:0;position:fixed;z-index:10049}#container.mobile-chat-popup{background:#fff;border-radius:12px;box-shadow:0 8px 24px #0003;display:flex;flex-direction:column;height:70dvh;left:50%;overflow:hidden;position:fixed;top:50%;transform:translate(-50%,-50%);width:90%;z-index:10050}#container.mobile-chat-hidden{display:none!important}.mobile-chat-header{align-items:center;background:#f7f7f7;border-bottom:1px solid #eee;display:flex;font-size:15px;font-weight:600;height:48px;justify-content:space-between;padding:0 12px}.mobile-chat-close{background:transparent;border:none;cursor:pointer;font-size:22px}.message-input input{padding:12px}.pcBtn{display:none}#showTextbooks .tab3{background-color:#fff;flex:1;overflow-y:auto;padding:12px 12px calc(60px + env(safe-area-inset-bottom));-webkit-overflow-scrolling:touch;min-height:0}.lesson-time{display:none}.toggle-btn{display:block;margin:2% auto 4%;padding:3% 10%;position:relative;right:auto;text-align:center;top:auto;width:90%}#count_time_leave{background-color:#fff3f3;border-bottom:1px solid #eee;border-radius:0;border-top:1px solid #eee;color:#d93025;font-size:14px;font-weight:700;left:0;margin:0 auto;padding:8px 12px;position:absolute;right:0;text-align:center;top:48px;z-index:999}#headerBar{height:48px;padding:0;position:relative}#headerBar .logo{margin-left:20px;width:120px}.rightInfo{background-color:green;bottom:0;display:none;display:none!important;position:fixed;width:100%;z-index:999}.user-name{display:none}#mainContainer{flex:1;flex-direction:column;height:100%;min-height:0;overflow:hidden;padding-bottom:calc(12px + env(safe-area-inset-bottom))}#leftContent{box-sizing:border-box;display:block;height:auto;overflow:hidden;width:100%}.button-group{display:flex}.button-group button{margin-bottom:6px;width:50%}.mobile-mask{background:#00000080;height:100%;left:0;position:fixed;top:0;width:100%;z-index:1999}#container.mobile-open{background:#fff;border-radius:0;box-shadow:0 8px 16px #0000004d;height:40%;justify-content:space-between;left:50%;padding:16px;position:fixed;top:50%;transform:translate(-50%,-50%);width:80%;z-index:2000}.close-button{background:transparent;border:none;cursor:pointer;position:absolute;right:0;top:-40px;z-index:10}.close-button img{height:40px;width:40px}#video-container{flex:1 1 auto;height:25vh;min-height:auto;overflow:hidden}.mobile-menu-icon{display:block;position:absolute;right:10px;width:48px}#showTextbooks{display:flex;flex-direction:column;height:100%;min-height:0;overflow:hidden;padding-top:0}#showTextbooks .tab1{flex:1;overflow-y:auto;padding:12px 12px 60px;-webkit-overflow-scrolling:touch;min-height:0}#showTextbooks iframe{border:none;height:100%;overflow:auto;width:100%;-webkit-overflow-scrolling:touch}.image-message{max-width:250px}.chat-image{max-height:150px}.image-upload-btn{padding:2px}#submitButton{padding:0 10px}.image-upload-btn .icon{width:100%}.screenshot-modal{margin:0;width:95vw}.screenshot-header{flex-direction:column;gap:12px;padding:12px}.screenshot-controls{justify-content:space-between;width:100%}.screenshot-controls button{flex:1;font-size:13px;padding:10px}.preview-actions{flex-direction:column;padding:12px 16px}.preview-actions button{justify-content:center;width:100%}.image-preview-content{border-radius:0;height:100%;margin:10px;max-height:100%;max-height:95%;max-width:100%;max-width:95%}.preview-image-container{max-height:60vh;min-height:200px;padding:10px}.preview-info{padding:12px 16px}.close-preview{height:36px;right:8px;top:8px;width:36px}.close-preview img{height:18px;width:18px}.device-form-group{align-items:stretch;flex-direction:column}.device-form-group label{text-align:left;width:auto}.device-form-group>#pre-local-player,.device-form-group>.progress{margin-left:0}#pre-local-player{width:100%!important}}@media (max-width:520px) and (max-height:740px){#video-container{flex:1 1 auto;height:28vh;min-height:auto;overflow:hidden}#leftContent{overflow-y:auto;-webkit-overflow-scrolling:touch;flex:1 1 auto}#local-video{height:80px;width:120px}#showTextbooks{flex:0 0 52vh;min-height:0}#showTextbooks .tab3{padding-bottom:calc(20px + env(safe-area-inset-bottom))}}