IronTemplates

Go to Ironband > Look and Feel and scrolldown to the bottom (Custom CSS),

Put in the textfield:

.marquee{
    height:500px;
}
.marquee .mask{
    max-height: 500px;
}
.marquee .tp-loader{height:500px}

Replace 500 by YourNumber number on the 3 lines. The number shall be the same for the 3 line.