TemplateMo - TemplateMo is a great place to get bootstrap templates from your website, which are all HTML5 supported with CSS layout.
Landingfolio - The best landing page designs for your inspiration.
Ethereal by HTML5 UP - A fully responsive side-scrolling one-page HTML5 template
Landing Pages in MailChimp - Easy to build, custom landing pages for free
UIdeck - Landing Page HTML Templates and UI Kits
SaaS Landing Page - The best SaaS landing page examples for design inspiration.