body{
    /* background-color: #333; */
    color: white;
}

header,main{
    background:#333;
}

.grid-container-main {
    display: grid;
    grid-template-columns: 60% 40%;
    /* border: 3px solid rgba(0, 0, 0, 0.8); */
    padding: 0px;
  
}

.footer{
   text-align: center;

}

.principal {
    flex-direction: column;
    align-items: flex-start;
    
    display: flex;
    justify-content: start;

    
}

.img-principal {
    margin:5px;
    width: 100%;
    float: right;
    height: 90%;
    filter: grayscale(66%);
    -webkit-filter: grayscale(66%);
}

.text-titulo{
    font-size: 3rem;
    margin-top: 100px;
    margin-left: 40px;
    
}

.text-subtitulo{
    font-size: 1.2rem;
    margin-left: 40px; 
}
.btn-estudiar {
    background-color: #1a66ff;
    font-size: 1.5rem;
    width: 50%;
    font-weight: bold;
    margin: 80px auto;
    border: none;
    color: white;
    padding: 15px 32px;
    text-align: center;
    text-decoration: none;
    display: inline-block;
    cursor: pointer;
    border-radius: 15px;
}


@media screen and (max-width: 900px) {

    .row,
    .navbar {
        flex-direction: column;
    }

    .container-img-principal{
        display: none;
    }
    .img-principal{
        display: none;
    }

    .grid-container-main {
        display: grid;
        grid-template-columns: 100% 0%;
        padding: 0px;
      
    }

    .btn-estudiar {
        width: 100%;
    }
}