**os**: macos Mojave 10.14.2 **env**: node v8.15.0 **version**(optimize-css-assets-webpack-plugin): 3.2.1 **error**:  **sourceCode**: ``` .tab-layer { width: 100%; height: calc(~'100vh - 0.97REM'); display: flex; flex-direction: column; position: relative; } ```