body{ 
    background-image: url(imagenes/fondo.jpg); background-repeat: no-repeat; background-attachment: fixed;background-size: cover; 
}
@media screen and (max-width: 900px){
    
}
#contenedor{
width: 100%; max-width: 500px;margin: auto;


}

a{  color:rgb(14, 13, 13);font-family: 'Bitter', serif;
    font-family: 'Montserrat', sans-serif;
    font-family: 'Roboto', sans-serif;
    font-family: 'Roboto Mono', monospace;

}



#txt{  height: 30px; width: 140px;margin-top: 0px; margin-left: 1500px; margin: 10px; color:rgb(22, 21, 21); text-align: center; font-size: 22px;
    font-family: 'Bitter', serif;
   font-family: 'Montserrat', sans-serif;
   font-family: 'Roboto', sans-serif;
   font-family: 'Roboto Mono', monospace; pad: 50px ;  background-color: rgb(223, 241, 61);
   
}
#menu{display: flex; width: 500px;padding: 10px; justify-content: space-between;font-family: 'Bitter', serif;
    font-family: 'Montserrat', sans-serif;
    font-family: 'Roboto', sans-serif;
    font-family: 'Roboto Mono', monospace; }





#operacion1{width: 400px; padding-left: 20px; color:black;
    margin:auto;  text-align: left;  margin-bottom: 20px;  font-family: 'Bitter', serif;
    font-family: 'Montserrat', sans-serif;
    font-family: 'Roboto', sans-serif;
    font-family: 'Roboto Mono', monospace; box-sizing: border-box;   }

    
button{ 
    background-color: rgb(241, 199, 12); color: rgb(12, 12, 12);
   
    margin: 0px;
    border-radius: 8px; text-align: center;
}
main{display: flex; box-sizing:border-box; margin: auto;}