Так попробуйте
<style>
#dt{
position:relative;
height: 25px;
background-color: cyan;
}
#dm{
position:relative;
height: 20%;
background-color: blue;
}
#df{
position:relative;
background-color: green;
}
</style>
<style>
body {
position: relative;
height: 100vh;
margin-top: 0;
margin-bottom: 0;
display: flex;
flex-direction:column;
}
#ourframe {
background-color: red;
position:relative;
flex-grow: 1;
}
</style>
<body>
<div id=dt> титул</div>
<div id=dm> меню</div>
<div id=ourframe> НАШ ФРЕЙМ</div>
<div id=df> футер</div>
</body>