style.css

* {
    box-sizing: border-box;
  }

body {
    width: 100%;
    display: block;
    margin: 0;
    min-height: 93vh;
    background: #4fdb9a;
    font-family: Georgia, 'Times New Roman', Times, serif;
    color: rgb(139, 16, 196);
    text-shadow: #444343 0 0 .09em;
}

.titulo_principal {
    color: rgb(139, 16, 196);
    font-size: 70px;
    text-transform: capitalize;
    text-align: center;
    display: block;
}

.formularios {
    width: 60vw;
    margin: auto;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    flex: 1 1 200px;
}

.form_encriptar,
.form-desencriptar {
    margin: 20px;
}

#entrada_texto, #salida_texto {
    font-family: Georgia, 'Times New Roman', Times, serif;
    font-size: 14px;
    color: rgb(95, 14, 133);
    background-color: #ade9cd;
    border: 3px solid rgb(95, 14, 133);
}

.formularios button {
    align-items: center;
    border-radius: 20px;
    padding: 5px 5px 5px 5px;
    margin-top: 10px;
    box-shadow: 20px 0px 30px -5px #5a5959;
    border: 2px solid rgb(95, 14, 133);
    background-color: rgb(95, 14, 133);
    color: #4fdb9a;
    cursor: pointer;
    font-family: Georgia, 'Times New Roman', Times, serif;
    font-size: 16px;
}

.formularios label {
    text-align: center;
}

.boton_izquierdo {
    margin-left: 100px;
}

.boton_derecho {
    margin-left: 10px;
}

.derechos {
    padding: 5px 5px 5px 5px;
    background-color: rgb(95, 14, 133);
    color: #4fdb9a;
    text-align: center;
    width: 100%;
    max-width: 100%;
    position: fixed;
    bottom: 0;
}