>>> getComputedStyle(document.body).getPropertyValue("--toolbar-height");
"60px"
参考: https://developer.mozilla.org/ja/docs/Web/CSS/Using_CSS_custom_properties#Values_in_JavaScript
>>> getComputedStyle(document.body).getPropertyValue("--toolbar-height");
"60px"
参考: https://developer.mozilla.org/ja/docs/Web/CSS/Using_CSS_custom_properties#Values_in_JavaScript