.split-screen { display: flex; /* Demo */ border: 1px solid #d1d5db; border-radius: 0.25rem; height: 100%; width: 100%; } .split-screen__half { flex: 1; /* Demo */ align-items: center; display: flex; justify-content: center; } .split-screen__half:first-child { border-right: 1px solid #d1d5db; }