text: document.getElementById("btn_regitrarse").addEventListener("click", register);
  document.getElementById("btn__iniciar-sesion").addEventListener("click", login);
  
  window.addEventListener("resize", anchoPagina);
  
  var contenedor_login_register = document.querySelector(".contenedor__login-register");
  var formulario_login = document.querySelector(".formulario__login");
  var caja_trasera_login = document.querySelector(".caja_trasera_login");
  var caja_trasera_register = document.querySelector(".caja_trasera_register");
  var formulario_registro = document.querySelector(".formulario__registro");
  
  
  function anchoPagina(){
      if(window.innerWidth > 850){
          caja_trasera_login.style.display = "block";
          caja_trasera_register.style.display = "block";
      }else{
          caja_trasera_register.style.display = "block";
          caja_trasera_register.style.opacity = "1";
          caja_trasera_login.style.display = "none";
          formulario_login.style.display = "block";
          formulario_registro.style.display = "none";
          contenedor_login_register.style.left = "0px";
      }
  }
  
  anchoPagina();
  
  function register(){
  
      if(window.innerWidth > 850){
      
      formulario_registro.style.display = "block";
      contenedor_login_register.style.left = "410px";
      formulario_login.style.display = "none";
      caja_trasera_register.style.opacity = "0";
      caja_trasera_login.style.opacity = "1";
  
      }else{
          formulario_registro.style.display = "block";
          contenedor_login_register.style.left = "0px";
          formulario_login.style.display = "none";
          caja_trasera_register.style.display = "none";
          caja_trasera_login.style.display = "block";
          caja_trasera_login.style.opacity = "1";
      }
  }
  
  function login(){
  
      if(window.innerWidth > 850){
  
      formulario_registro.style.display = "none";
      contenedor_login_register.style.left = "10px";
      formulario_login.style.display = "block";
      caja_trasera_register.style.opacity = "1";
      caja_trasera_login.style.opacity = "0";
  
      }else{
          formulario_registro.style.display = "none";
          contenedor_login_register.style.left = "0px";
          formulario_login.style.display = "block";
          caja_trasera_register.style.display = "block";
          caja_trasera_login.style.display = "none";
      }
  }