Apple System in action on shopify.github.io

Under the hood

.header-1 { font-family: -apple-system, system-ui, "San Francisco", Roboto, "Segoe UI", "Helvetica Neue", sans-serif; font-size: 64px; font-style: normal; font-weight: 700; letter-spacing: normal; line-height: 83px; text-transform: none; color: #000000; }
.content-1 { font-family: -apple-system, system-ui, "San Francisco", Roboto, "Segoe UI", "Helvetica Neue", sans-serif; font-size: 24px; font-style: normal; font-weight: 700; letter-spacing: normal; line-height: 38px; text-transform: none; color: #000000; }