.form-group {
  
  color:green;
     font-size: 24px;
        font-family: Arial, sans-serif;
          display: flex;
  justify-content: center;
  position: fixed;
  
  
}
 


.btn   {
    bottom: 677px;
   width: 30%;
  height: 34px;
 
  color:red;
     font-size: 30px;
        font-family: Arial, sans-serif;
          display: flex;
  justify-content: center;
  position: fixed;
}

.col-lg-8  {
  bottom: 1000px;
   width: 40%;
  height: 64px;
  
  color:red;
     font-size: 34px;
        font-family: Arial, sans-serif;
          position: absolute;
  justify-content: center;
  
}

.col-xs-12  {
  top: 200px;
   width: 20%;
  height: 64px;
  
  color:blue;
     font-size: 34px;
        font-family: Arial, sans-serif;
          position: absolute;
  justify-content: center;
  
}

.form-   group {
   top: 300px;
   width: 70%;
  height: 64px;
  
  color:blue;
     font-size: 34px;
        font-family: Arial, sans-serif;
          position: absolute;
  justify-content: center;
  
}


.comentario   {
  
   width: 80%;
  height:64px;
  
  color:blue;
     font-size: 44px;
        font-family: Arial, sans-serif;
          display: flex;
  justify-content: center;
  position: fixed;
}


.author   {
  
   width: 80%;
  height:64px;
  
  color:blue;
     font-size: 44px;
        font-family: Arial, sans-serif;
          display: flex;
  justify-content: center;
  position: fixed;
}



.container {
  
  color:grey;
     font-size: 44px;
        font-family: Arial, sans-serif;
  
}

 .container px-4{
     
   color:green;  
      
     
       
}

.contact {
  
  
     font-size: 14px;
        font-family: Arial, sans-serif;
  
}

 
    
                <div class="container px-4">
                    <div class="row gx-4 justify-content-center">