Decide exactly what happens when your text is longer than the box that holds it. With Overflow behavior, a fixed-size text box can scroll its content, shrink to fit, trim with an ellipsis, or clip cleanly at the edge, so your layout stays intact no matter how much copy you add.
When you place text in a design, the text box normally grows to fit whatever you type. That works well most of the time, but in a fixed-size banner, a longer headline or a long block of legal copy can push past the space you planned for it.
Overflow behavior gives you control over that moment. You set the text box to a fixed size, then tell Bannersnack what to do with any text that does not fit: scroll it, shrink it, trim it with an ellipsis, or clip it at the edge.
When These Options Appear
Overflow behavior only applies to text boxes with a fixed height. In the Text panel you will see a toggle:
Auto height – the box grows or shrinks so it always fits the text. There is no overflow to manage.
Fixed height – the box keeps the exact size you set, and you choose how any extra text behaves.
Switch a text box to Fixed height to reveal the four Overflow behavior options.
How to Set Overflow Behavior
Select a text element on your canvas, or add one from the Text panel.
In the Text panel, find the height setting and switch from Auto height to Fixed height.
Resize the text box to the size you want by dragging its handles. This is the space your text has to work with.
Under Overflow behavior, choose one of the four options: Clip, Scroll, Shrink, or Ellipsis.
If you choose Scroll, set the Scroll speed and Scroll start delay to control the motion.
Preview your design to check how the text behaves inside the box.
The Four Overflow Behaviors
Clip
Any text that goes past the edge of the box is hidden. The box keeps its exact size and position, and the extra text is simply not shown. Clip is useful when you want a strict boundary and would rather cut text off than let it change your layout.
Scroll (Auto-Scroll for ISI)
The text scrolls vertically inside the fixed box, so viewers can read all of it over time even when it is much longer than the space allows. This is built for ISI (Important Safety Information), the long regulatory and legal copy that pharma, finance, and other regulated ads are required to include.
When you select Scroll, two extra controls appear:
Scroll speed – how fast the text moves through the box.
Scroll start delay – how long the text stays still before it starts scrolling, in seconds. A short delay lets viewers read the opening lines before the motion begins.
Scroll keeps a small banner compliant with long-form safety text without forcing you into a taller ad unit.
Shrink
The font size automatically reduces until all of the text fits inside the box. Nothing is hidden and nothing scrolls; the text just gets smaller so the whole message stays visible. Shrink is a good fit for templated or dynamic designs where copy length varies and you want everything to remain readable in the same footprint.
Ellipsis
The text is trimmed at the edge of the box and an ellipsis (…) is added to show that more text exists than the space can display. Ellipsis keeps a clean, predictable layout and signals to the viewer that the message continues.
Why Use Overflow Behavior
Fixed-size ad units are unforgiving. A headline that runs one line longer than expected, or a block of legal copy that keeps growing, can break an otherwise clean design. Overflow behavior lets you lock the box and choose a deliberate outcome, instead of letting the text decide the layout for you.
It is especially helpful for:
Standard HTML5 banner sizes where every pixel is spoken for
ISI and other legal or regulatory copy that has to appear in full
Dynamic or templated designs where the same layout carries different copy lengths
Any design where you want text length to stay consistent across variations
Best Practices
Set the box to the exact size you need before choosing a behavior, so you are deciding overflow against the real space.
Use Scroll for long compliance text like ISI, and give it a short start delay so the first lines are readable before the motion begins.
Use Shrink when keeping every word visible matters more than a consistent font size.
Use Ellipsis for headlines and short labels where a clean cut-off reads better than shrinking the type.
Use Clip when you want a hard boundary and are comfortable hiding anything that does not fit.
Preview the design, and check the HTML5 output, to confirm the text behaves the way you expect before you publish.
Tips
Overflow behavior works well for:
Pharma and healthcare banners with ISI text
Finance and insurance ads with required disclosures
Fixed-size HTML5 display ads
Templated banner sets where copy changes across sizes
Any layout where text length needs to stay under control
By choosing how a fixed text box handles extra copy, you keep full control of your design while letting the text adapt to the space.
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