CSS实现表格对角线

        td {
            background-size: 100% 100%;
            background-image: url("data:image/svg+xml;base64,PHN2ZyB3aWR0aD0iMTAwJSIgaGVpZ2h0PSIxMDAlIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPg0KICA8bGluZSB4MT0iMCIgeTE9IjAiIHgyPSIxMDAlIiB5Mj0iMTAwJSIgc3Ryb2tlPSJibGFjayIgLz4NCjwvc3ZnPg==");
        }