We present an approach how to combine large mode field diameters with effective single-mode guidance in a hollow-core antiresonant optical fiber. We demonstrate experimentally and in simulations that single-mode guidance is achieved in a simplified hollow-core fiber design with a core diameter of 30 μm by shifting the effective indices of the first cladding modes close to those of higher-order core modes. Our fiber shows low loss propagation and effective single-mode Operation from the near infrared to deep ultraviolet wavelengths down to 270 nm on a loss level of approximately 3dB/m.