Suppose there are two random variables $X$ and $Y$ with continuous support $[0,1]$ and bivariate distribution of $X$ and $Y$, $F$.
What would be the value of CDF $F(x,0)$ when $x\in[0,1]$? Is it just 0 because there is no atom in a continuous distribution?
Yes. $P\{X,\leq x,Y\leq 0\}\leq P\{Y\leq 0\}=0$.