Hire attitude, teach skills.
Have people explain how and why they chose their current tech stack. If they don't get to choose in their current or past role, ask what they would choose for a green fields project and why.
Ask questions about how they advocate their ideas and handle different opinions on their team.
Ask them to describe the way they work with other disciplines - backend, design, QA, managers, marketing, support...
Ask them what they're proud of.
Ask them about their toughest learning experiences.
Ask them what they're excited about.
If you still don't know about their skills in a key area - ask them directly. HTML? CSS? JS? Accessibility? Test frameworks? ...but usually a great dev will have talked about this stuff already.
Be willing to wait to get the right people. Hire up to a standard, not to a deadline. No matter how tough the pressure, a bad hire will take more time and energy than waiting.