* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

.menu {
    height: 100px;
    background-color: #B2D6FF;    /* Medium blue */
}
  
.sidebar {
    float: left;
    width: 200px; 
    height: 300px;
    background-color: #F09A9D;    /* Red */
}
  
.content {
    height: 500px;
    background-color: #F5CF8E;    /* Yellow */
}
  
.footer {
    height: 200px;
    background-color: #D6E9FE;    /* Light blue */
}
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

.page {
    width: 900px;
    margin: 0 auto;
}

.menu {
    height: 100px;
    background-color: #B2D6FF;    /* Medium blue */
}
  
.sidebar {
    float: left;
    width: 200px; 
    height: 300px;
    background-color: #F09A9D;    /* Red */
}
  
.content {
    height: 500px;
    background-color: #F5CF8E;    /* Yellow */
}
  
.footer {
    height: 200px;
    background-color: #D6E9FE;    /* Light blue */
}
Add floating inside of parents
Add floating inside of parents
