Helvetica Neue with Neue Haas Grotesk in action on bxswiss.com

Under the hood

.header-1 { font-family: NHaasGroteskMd, 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 48px; font-style: normal; font-weight: normal; letter-spacing: -1px; line-height: 52px; text-transform: none; color: #282828; }
.content-1 { font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 14px; font-style: normal; font-weight: bold; letter-spacing: normal; line-height: 21px; text-transform: none; color: #282828; }