/* 由 scripts/optimize_model_thumbnails.py 生成；原图保留，沿用懒加载开关。 */
.diagram-elastic-contact-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/elastic-contact-3d-ch3-png-7ec119dbda2a.webp"))!important}
.diagram-force-analysis-trainer{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/force-analysis-trainer-ch3-png-1019dd06889f.webp"))!important}
.diagram-hooke-law{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/hooke-law-ch3-png-f73212271beb.webp"))!important}
.diagram-sliding-friction-control{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/sliding-friction-control-ch3-png-d5f93fed16f9.webp"))!important}
.diagram-static-friction-threshold{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/static-friction-threshold-ch3-png-47d371821163.webp"))!important}
.diagram-friction-direction{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/friction-direction-ch3-png-ba67e69265ea.webp"))!important}
.diagram-force-composition{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/force-composition-ch3-png-3fdb0d44bc2d.webp"))!important}
.diagram-force-decomposition{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/force-decomposition-ch3-png-6161f91018ef.webp"))!important}
.diagram-double-rope-tension{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/double-rope-tension-ch3-png-b65cb2d13a57.webp"))!important}
.diagram-three-force-equilibrium{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/three-force-equilibrium-ch3-png-88cc44943059.webp"))!important}