/* 由 scripts/optimize_model_thumbnails.py 生成；原图保留，沿用懒加载开关。 */
.diagram-pressure{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/liquid-pressure-png-289e229e2298.webp"))}
.diagram-pump{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/pump-jpg-a20f827f5ce5.webp"))}
.diagram-lens{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/lens-jpg-203f01c5b70e.webp"))}
.diagram-ray{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/ray-jpg-c03a651aeb83.webp"))}
.diagram-resistor{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/rheostat-png-b2126dbbfcad.webp"))}
.diagram-circuit{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/circuit-jpg-57deceebca95.webp"))}
.diagram-lever{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/lever-png-4b37df712f24.webp"))}
.diagram-float{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/float-png-a1bb084072be.webp"))}
.diagram-thermo{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/thermo-jpg-2d9aa8c32259.webp"))}
.diagram-atmosphere{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/atmosphere-jpg-a90563711d81.webp"))}
.diagram-incline{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/incline-jpg-bda419ff7e36.webp"))}
.diagram-pulley{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/pulley-jpg-a227dd54f8d4.webp"))}
.diagram-energy{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/energy-jpg-e0d39cf2901a.webp"))}
.diagram-inertia{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/inertia-jpg-a8ad9fd2a936.webp"))}
.diagram-electromagnet{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/electromagnet-jpg-b8f84b32ba7c.webp"))}
.diagram-engine{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/engine-jpg-3b23308bf84c.webp"))}
.diagram-generator{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/generator-png-a5f6baa17235.webp"))}
.diagram-friction{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/friction-png-bc2a8c7eded9.webp"))}
.diagram-household{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/household-3d-png-02c8c76f8b03.webp"))}
.diagram-mirror{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/mirror-jpg-a8942c96cbf2.webp"))}
.diagram-balance{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/balance-png-f7d886d11135.webp"))}
.diagram-electrolysis{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/electrolysis-png-377626e66419.webp"))}
.diagram-oxygen{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/oxygen-png-d9a021de5590.webp"))}
.diagram-solubility{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/solubility-png-243cc5747a3e.webp"))}
.diagram-ph{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/ph-indicator-png-e841bba9d06b.webp"))}
.diagram-metal{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/metal-activity-png-09cc7de916eb.webp"))}
.diagram-rust{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/iron-rusting-png-87d4509e1962.webp"))}
.diagram-co-reduction{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/co-cuo-reduction-png-776097866b06.webp"))}
.diagram-projectile{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/projectile-motion-png-a1496a23bec8.webp"))}
.diagram-cart-force-inference{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/cart-force-inference-png-7e2f78bfe651.webp"))}
.diagram-force-decomposition{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/force-decomposition-png-cf774427c6c7.webp"))}
.diagram-friction-direction{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/friction-direction-png-50b35fa21099.webp"))}
.diagram-double-rope-tension{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/double-rope-tension-png-ecd0a5f5d4bb.webp"))}
.diagram-three-force-equilibrium{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/three-force-equilibrium-png-db48d2059c2e.webp"))}
.diagram-curvilinear-motion{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/curvilinear-motion-png-9dc85f0f9ec1.webp"))}
.diagram-motion-composition{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/motion-composition-png-8cd4de54eaa8.webp"))}
.diagram-projectile-experiment{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/projectile-experiment-png-17002b180e9a.webp"))}
.diagram-projectile-applications{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/projectile-applications-png-69fa27708b40.webp"))}
.diagram-oblique-throw{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/oblique-throw-png-dcf8656863fd.webp"))}
.diagram-circular-speed-period{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/circular-speed-period-png-f9264330bc8e.webp"))}
.diagram-kepler-laws{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/kepler-laws-png-1dd4f38ea9b2.webp"))}
.diagram-sound-classic{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/sound-classic-jpg-3b2001eb0f06.webp"))}
.diagram-sound-properties{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/sound-properties-jpg-955c1fed9088.webp"))}
.diagram-chemistry-classification{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/chemistry-classification-png-96b37be7ca6c.webp"))}
.diagram-colloid-tyndall{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/colloid-tyndall-png-385c559192b5.webp"))}
.diagram-chemical-transformation-routes{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/chemical-transformation-routes-png-6884e4f22149.webp"))}
.diagram-electrolyte-ionization{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/electrolyte-ionization-png-96c1a939a21c.webp"))}
.diagram-ionic-reaction-essence{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/ionic-reaction-essence-png-4a1307113df7.webp"))}
.diagram-ionic-equation-workbench{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/ionic-equation-workbench-png-08209fe99108.webp"))}
.diagram-barium-acid-conductivity{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/barium-acid-conductivity-png-9e5f84900589.webp"))}
.diagram-redox-electron-transfer{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/redox-electron-transfer-png-7519b3da44b8.webp"))}
.diagram-iron-copper-redox{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/iron-copper-redox-png-94d02a598bc4.webp"))}
.diagram-matter-changes-review{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/matter-changes-review-png-edbbd175bf2a.webp"))}
.diagram-physical-chemical-changes{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/physical-chemical-changes-png-ea068dc888be.webp"))}
.diagram-candle-burning-inquiry{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/candle-burning-inquiry-png-e152cedb0d0b.webp"))}
.diagram-chemical-reagent-handling{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/chemical-reagent-handling-png-530c3140b45f.webp"))}
.diagram-measuring-cylinder-reading{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/measuring-cylinder-reading-png-2f7506ffa6a0.webp"))}
.diagram-alcohol-lamp-heating{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/alcohol-lamp-heating-png-d82e14a53ac4.webp"))}
.diagram-apparatus-airtightness{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/apparatus-airtightness-png-12d856b4d3a3.webp"))}
.diagram-oxygen-carbon-dioxide-properties{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/oxygen-carbon-dioxide-properties-png-ccb4a7475989.webp"))}
.diagram-enter-chemistry-review{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/enter-chemistry-review-png-2ce4ed7f9c93.webp"))}
.diagram-bird-respiration-air-sacs{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/bird-respiration-air-sacs-png-dbb426cc4c21.webp"))}
.diagram-inclined-chute-displacement{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/inclined-chute-displacement-png-0c468ea7790c.webp"))}
.diagram-photogate-speed-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/photogate-speed-3d-png-af71c5cfd765.webp"))}
.diagram-heart-circulation-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/heart-circulation-3d-png-4f3851b61976.webp"))}
.diagram-magnifier-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/magnifier-3d-png-a16f04813c45.webp"))}
.diagram-projector-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/projector-3d-png-b1853e4e12f1.webp"))}
.diagram-microscope-optics-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/microscope-optics-3d-png-9f83759d0605.webp"))}
.diagram-telescope-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/telescope-3d-png-a304e7f5ac04.webp"))}
.diagram-ticker-timer-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/ticker-timer-3d-png-2f6edeb870a3.webp"))}
.diagram-spring-oscillator-studio{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/spring-oscillator-studio-png-d3246ae776ad.webp"))}
.diagram-microscope-structure-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/microscope-structure-3d-png-38fcaca1e9ae.webp"))}
.diagram-sodium-compounds{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/sodium-compounds-png-0f60d46c07b6.webp"))}
.diagram-cell-microscope-studio{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/cell-microscope-studio-png-e0138182f86c.webp"))}
.diagram-gasoline-engine-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/gasoline-engine-3d-png-a09702950e82.webp"))}
.diagram-newton-third-law{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/newton-third-law-png-df1c37259079.webp"))}
.diagram-projectile-comparison-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/projectile-comparison-3d-png-419c12e2ae7e.webp"))}
.diagram-buoyancy-experiment-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/buoyancy-experiment-3d-png-60348ea0a2a6.webp"))}
.diagram-spring-balance-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/spring-balance-3d-png-bad223301069.webp"))}
.diagram-archimedes-experiment-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/archimedes-experiment-3d-png-09f5de44c66c.webp"))}
.diagram-specific-heat-capacity{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/specific-heat-capacity-png-ff4fbda45d64.webp"))}
.diagram-molecular-thermal-motion{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/molecular-thermal-motion-png-0a6a6336cd7e.webp"))}
.diagram-internal-energy-change{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/internal-energy-change-png-60db5fc1d0ed.webp"))}
.diagram-two-force-balance-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/two-force-balance-3d-png-48aa40a5f113.webp"))}
.diagram-pressure-effect-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/pressure-effect-3d-png-95934a6a4e69.webp"))}
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.diagram-work-power{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/work-power-jpg-89ea7115b662.webp"))}
.diagram-kinetic-energy-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/kinetic-energy-3d-jpg-43c225f14dae.webp"))}
.diagram-voltage-measurement{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/voltage-measurement-png-4578fb46949a.webp"))}
.diagram-potential-energy-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/potential-energy-3d-jpg-0d56e71edcb2.webp"))}
.diagram-resistance-factors{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/resistance-factors-png-63f2ea5adfda.webp"))}
.diagram-current-voltage-relationship{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/current-voltage-relationship-png-216c35aaa1db.webp"))}
.diagram-buoyancy-applications-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/buoyancy-applications-3d-jpg-e35a34e49125.webp"))}
.diagram-resistance-measurement{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/resistance-measurement-png-d9087be5bce3.webp"))}
.diagram-lamp-power{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/lamp-power-png-ab9bbc9f5273.webp"))}
.diagram-hydrometer-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/hydrometer-3d-jpg-361a02910213.webp"))}
.diagram-fluid-pressure-speed{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/fluid-pressure-speed-png-415c72f8e873.webp"))}
.diagram-circuit-diagnosis{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/circuit-diagnosis-png-cfaff77e03c7.webp"))}
.diagram-steelyard-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/steelyard-3d-jpg-20d4722e9765.webp"))}
.diagram-electroscope{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/electroscope-png-d70e5176cdb5.webp"))}
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.diagram-dimming-lamp{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/dimming-lamp-png-dc7486103e89.webp"))}
.diagram-junior-gravity{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/junior-gravity-png-4385557adb14.webp"))}
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.diagram-collinear-forces{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/collinear-forces-png-98e65f31b434.webp"))}
.diagram-household-energy{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/household-energy-png-2fdc529b062c.webp"))}
.diagram-joule-heating{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/joule-heating-png-452ed816f185.webp"))}
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.diagram-energy-transformation-conservation{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/energy-transformation-conservation-png-fa454a0b8282.webp"))}
.diagram-fuel-heat-value-efficiency{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/fuel-heat-value-efficiency-png-54b8968183ca.webp"))}
.diagram-simple-heat-engine-build{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/simple-heat-engine-build-png-ca863dc0fb9b.webp"))}
.diagram-circuits-classic{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/circuits-classic-jpg-cfdac4b7a5ab.webp"))}
.diagram-piston-pump-classic{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/piston-pump-classic-jpg-a8e977148a50.webp"))}
.diagram-efficiency-classic{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/efficiency-classic-jpg-befd95ecdf95.webp"))}
.diagram-inertia-classic{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/inertia-classic-jpg-557e2c80cc90.webp"))}
.diagram-atmosphere-classic{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/atmosphere-classic-jpg-fbc2cff01eab.webp"))}
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.diagram-gasoline-engine-classic{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/gasoline-engine-classic-png-6ed98c70ae0e.webp"))}
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.diagram-precision-measurement-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/precision-measurement-3d-jpg-1f5107b70253.webp"))}
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.diagram-solution-preparation{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/solution-preparation-jpg-79fdc0091c15.webp"))}
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.diagram-periodic-elements-lab{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/periodic-elements-lab-png-9d2de1131878.webp"))}
.diagram-double-slit-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/double-slit-3d-png-5657280bd042.webp"))}
.diagram-air-wedge-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/air-wedge-3d-png-2f921a7c5653.webp"))}
.diagram-cyclotron-3d{background-image:var(--thumbnail-load,url("/static/model-thumbnails/cards/cyclotron-3d-png-4086c6addb90.webp"))}