style.css

body {
    font-family: "Roboto", sans-serif;
    font-weight: 400;
    font-style: normal;
}
header{
    background: #f3f5fc;
    padding: 12px;
    padding-left: 10%;
    
}
.titulo{
    display: inline-block;
    color: #0A3871;
    font-family: "Roboto", sans-serif;
    font-size: 50px;
    padding-left: 30px;
}
.alura{
    color: #0A3871;
    font-family: "Roboto", sans-serif;
    font-size: 25px;
    padding-left: 170px;
    padding-top: 10px;
}
main{
    width: 100%;
    background: #f3f5fc;
    display: grid;
    grid-template-areas:
    "izquierda derecha";
    grid-template-columns: 70% 30%;
    grid-template-rows: 95%;
}
.izq{
    
    padding: 3em;
    margin: 22px 121px;
}
textarea{
    border: none;
    resize: none;
}
.texto-encriptado  {
    background: #f3f5fc;
    width: 100%;
    height: 450px;
    font-size: 30px;
    font-family: "Roboto", sans-serif;
    color: #0A3871;
  }
.izq p{
    margin-bottom: 15px;
}
.izq textarea::placeholder{
    color: #0A3871;
    font-family: "Roboto", sans-serif;
    font-size: 30px;
}
.izquierda textarea:focus::placeholder{
    color: #bfd5f0;
    font-family: "Roboto", sans-serif;
    font-size: 30px;
}
.boton{
    display: block;
    
}
  button {
    cursor: pointer;
    border: 1px solid #0A3871;
    border-radius: 25px;
    height: 57px;
    font-size: 16px;
}
.boton-encriptar{
    width: 48%;
    color: #D8DFE8;
    background: #0A3871;
}
.boton-desencriptar {
    width: 48%;
    color: #0A3871;
    background: #D8DFE8;
    margin-left: 3%;
}

  /*A la derecha*/

.der {
    background: #FFFFFF;
    border-radius: 15px;
    margin: 20px 20px 20px 0 ;
    text-align: center;
    box-sizing: border-box;
    box-shadow: 15px 10px 25px gray;
    
}
.der textarea {
    background: #ffffff;
    width: 93%;
    height: 350px;
    font-size: 25px;
    font-family: "Roboto", sans-serif;
    color: #495057;
    border-radius: 15px;
    padding: 12px;
    padding-right: 5%;
}
.imagen-mensaje{
    margin-top: 25%;
}
.imagen-mensaje img{
    width: 70%;
}
.boton-copiar {
    width: 80%;
    color: #0A3871;
    background: #D8DFE8;
    vertical-align: bottom;
    margin-left: 3%;
}
  footer {
    text-align: center;
    color: #f6fbf5;
    background: #0A3871;
    margin: 0;
    padding: 5px;
}