A celebratory crowd of thousands bundled up on a raw Tuesday afternoon to watch President Joe Biden sign gay marriage legislation into law, a joyful ceremony that was tempered by the backdrop of an ongoing conservative backlash over gender issues. “This law and the love it defends strike a blow against hate in all its forms,” Biden said on the South Lawn of the White House. “And that's why this law matters to every single American.” Singers Sam Smith and Cyndi Lauper performed. Vice President Kamala Harris recalled officiating at a lesbian wedding in San Francisco. And the White House...