General recommendation for HTML banner creators
- banner - data size of a file cannot be higher than maximal limit defined by publisher. When creating, be aware of total data volume (incl. external sources that are necessary for banner displaying. Follow the same rules for ad creatives such as flash, image video, etc.
- images - use as few images as possible. CSS may be used for the rest. Compress images. Use .jpg format for photographs (large rage of colours is available), .png format for icons, illustrations and pictures with transparent background.
- CSS - write as inline style or in front of article banner HTML to <style> tag
Choose only styles that will be used in the banner. Choose CSS selectory as accurately as possible in order to minimalize problems with possible interference of CSS into page design where the banner will be displayed.
HTML banners are used in modern browsers that supports CSS3 and other technical specifications. Therefore, we do recommend use these characteristics of CSS. If possible, create banner animation only in CSS. - JavaScript - if it you need to use JavaScript code, do not use external library. Insert JavaScript in front of HTML banner code or behind it.
- HTML – a banner must contain only HTML required for banner display. Omit HTML document requirements such as head, body and meta tags. Remember that the banner must be possible to display on a website either in iframe or without it.
Find IAB information about HTML5 banners HERE and HERE