background: linear-gradient( to top right, rgba(0, 0, 0, 0) 0%, rgba(0, 0, 0, 0) calc(50% - 1.5px), rgba(0, 0, 0, 1) 50%, rgba(0, 0, 0, 0) calc(50% + 1.5px), rgba(0, 0, 0, 0) 100% ), linear-gradient( to bottom right, rgba(0, 0, 0, 0) 0%, rgba(0, 0, 0, 0) calc(50% - 1.5px), rgba(0, 0, 0, 1) 50%, rgba(0, 0, 0, 0) calc(50% + 1.5px), rgba(0, 0, 0, 0) 100% );