Pop upbeat with a bright dance groove and bouncy four-on-the-floor pulse; verse rides light piano and handclaps, pre-chorus lifts with stacked harmonies and rising snare rolls, chorus hits with glossy synth hooks and gang-style backing vocals on the birthday chant. Close-mic lead vocal, warm doubled chorus lines, playful ad-libs, confetti risers and tambourine shimmers between phrases. Bright, punchy, celebratory mix.