Login Modal

.html

<div class="scroll-down">SCROLL DOWN
  <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32">
  <path d="M16 3C8.832031 3 3 8.832031 3 16s5.832031 13 13 13 13-5.832031 13-13S23.167969 3 16 3zm0 2c6.085938 0 11 4.914063 11 11 0 6.085938-4.914062 11-11 11-6.085937 0-11-4.914062-11-11C5 9.914063 9.914063 5 16 5zm-1 4v10.28125l-4-4-1.40625 1.4375L16 23.125l6.40625-6.40625L21 15.28125l-4 4V9z"/> 
</svg></div>
<div class="container"></div>
<div class="modal">
  <div class="modal-container">
    <div class="modal-left">
      <h1 class="modal-title">Welcome!</h1>
      <p class="modal-desc">Fanny pack hexagon food truck, street art waistcoat kitsch.</p>
      <div class="input-block">
        <label for="email" class="input-label">Email</label>
        <input type="email" name="email" id="email" placeholder="Email">
      </div>
      <div class="input-block">
        <label for="password" class="input-label">Password</label>
        <input type="password" name="password" id="password" placeholder="Password">
      </div>
      <div class="modal-buttons">
        <a href="" class="">Forgot your password?</a>
        <button class="input-button">Login</button>
      </div>
      <p class="sign-up">Don't have an account? <a href="#">Sign up now</a></p>
    </div>
    <div class="modal-right">
      <img src="https://images.unsplash.com/photo-1512486130939-2c4f79935e4f?ixlib=rb-0.3.5&ixid=eyJhcHBfaWQiOjEyMDd9&s=dfd2ec5a01006fd8c4d7592a381d3776&auto=format&fit=crop&w=1000&q=80" alt="">
    </div>
    <button class="icon-button close-button">
        <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 50 50">
    <path d="M 25 3 C 12.86158 3 3 12.86158 3 25 C 3 37.13842 12.86158 47 25 47 C 37.13842 47 47 37.13842 47 25 C 47 12.86158 37.13842 3 25 3 z M 25 5 C 36.05754 5 45 13.94246 45 25 C 45 36.05754 36.05754 45 25 45 C 13.94246 45 5 36.05754 5 25 C 5 13.94246 13.94246 5 25 5 z M 16.990234 15.990234 A 1.0001 1.0001 0 0 0 16.292969 17.707031 L 23.585938 25 L 16.292969 32.292969 A 1.0001 1.0001 0 1 0 17.707031 33.707031 L 25 26.414062 L 32.292969 33.707031 A 1.0001 1.0001 0 1 0 33.707031 32.292969 L 26.414062 25 L 33.707031 17.707031 A 1.0001 1.0001 0 0 0 32.980469 15.990234 A 1.0001 1.0001 0 0 0 32.292969 16.292969 L 25 23.585938 L 17.707031 16.292969 A 1.0001 1.0001 0 0 0 16.990234 15.990234 z"></path>
</svg>
      </button>
  </div>
  <button class="modal-button">Click here to login</button>
</div>

.css

@import url("https://fonts.googleapis.com/css?family=Nunito:400,600,700");

* {
  box-sizing: border-box;
}

body {
  font-family: "Nunito", sans-serif;
  color: rgba(#000, 0.7);
}

.container {
  height: 200vh;
  background-image: url(https://images.unsplash.com/photo-1538137524007-21e48fa42f3f?ixlib=rb-0.3.5&ixid=eyJhcHBfaWQiOjEyMDd9&s=ac9fa0975bd2ebad7afd906c5a3a15ab&auto=format&fit=crop&w=1834&q=80);
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
}

.modal {
  position: fixed;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 60px;
  background: rgba(#333, 0.5);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  transition: 0.4s;

  &-container {
    display: flex;
    max-width: 720px;
    width: 100%;
    border-radius: 10px;
    overflow: hidden;
    position: absolute;
    opacity: 0;
    pointer-events: none;
    transition-duration: 0.3s;
    background: #fff;
    transform: translateY(100px) scale(0.4);
  }

  &-title {
    font-size: 26px;
    margin: 0;
    font-weight: 400;
    color: #55311c;
  }

  &-desc {
    margin: 6px 0 30px 0;
  }

  &-left {
    padding: 60px 30px 20px;
    background: #fff;
    flex: 1.5;
    transition-duration: 0.5s;
    transform: translateY(80px);
    opacity: 0;
  }

  &-button {
    color: darken(#8c7569, 5%);
    font-family: "Nunito", sans-serif;
    font-size: 18px;
    cursor: pointer;
    border: 0;
    outline: 0;
    padding: 10px 40px;
    border-radius: 30px;
    background: rgb(255, 255, 255);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.16);
    transition: 0.3s;
    
    &:hover {
      border-color: rgba(255, 255, 255, 0.2);
      background: rgba(#fff, 0.8);
    }
  }

  &-right {
    flex: 2;
    font-size: 0;
    transition: 0.3s;
    overflow: hidden;

    img {
      width: 100%;
      height: 100%;
      transform: scale(2);
      object-fit: cover;
      transition-duration: 1.2s;
    }
  }

  &.is-open {
    height: 100%;
    background: rgba(#333, 0.85);

    .modal-button {
      opacity: 0;
    }

    .modal-container {
      opacity: 1;
      transition-duration: 0.6s;
      pointer-events: auto;
      transform: translateY(0) scale(1);
    }

    .modal-right img {
      transform: scale(1);
    }

    .modal-left {
      transform: translateY(0);
      opacity: 1;
      transition-delay: 0.1s;
    }
  }

  &-buttons {
    display: flex;
    justify-content: space-between;
    align-items: center;

    a {
      color: rgba(#333, 0.6);
      font-size: 14px;
    }
  }
}

.sign-up {
  margin: 60px 0 0;
  font-size: 14px;
  text-align: center;

  a {
    color: #8c7569;
  }
}

.input-button {
  padding: 8px 12px;
  outline: none;
  border: 0;
  color: #fff;
  border-radius: 4px;
  background: #8c7569;
  font-family: "Nunito", sans-serif;
  transition: 0.3s;
  cursor: pointer;

  &:hover {
    background: #55311c;
  }
}

.input-label {
  font-size: 11px;
  text-transform: uppercase;
  font-family: "Nunito", sans-serif;
  font-weight: 600;
  letter-spacing: 0.7px;
  color: #8c7569;
  transition: 0.3s;
}

.input-block {
  display: flex;
  flex-direction: column;
  padding: 10px 10px 8px;
  border: 1px solid #ddd;
  border-radius: 4px;
  margin-bottom: 20px;
  transition: 0.3s;

  input {
    outline: 0;
    border: 0;
    padding: 4px 0 0;
    font-size: 14px;
    font-family: "Nunito", sans-serif;

    &::placeholder {
      color: #ccc;
      opacity: 1;
    }
  }

  &:focus-within {
    border-color: #8c7569;

    .input-label {
      color: rgba(#8c7569, 0.8);
    }
  }
}

.icon-button {
  outline: 0;
  position: absolute;
  right: 10px;
  top: 12px;
  width: 32px;
  height: 32px;
  border: 0;
  background: 0;
  padding: 0;
  cursor: pointer;
}

.scroll-down {
  position: fixed;
  top: 50%;
  left: 50%;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  color: darken(#8c7569, 5%);
  font-size: 32px;
  font-weight: 800;
  transform: translate(-50%, -50%);
  svg {
    margin-top: 16px;
    width: 52px;
    fill: currentColor;
  }
}


@media(max-width: 750px) {
  .modal-container {
    width: 90%;
  }
  .modal-right {
    display: none;
  }
}

.js

const body = document.querySelector("body");
const modal = document.querySelector(".modal");
const modalButton = document.querySelector(".modal-button");
const closeButton = document.querySelector(".close-button");
const scrollDown = document.querySelector(".scroll-down");
let isOpened = false;

const openModal = () => {
  modal.classList.add("is-open");
  body.style.overflow = "hidden";
};

const closeModal = () => {
  modal.classList.remove("is-open");
  body.style.overflow = "initial";
};

window.addEventListener("scroll", () => {
  if (window.scrollY > window.innerHeight / 3 && !isOpened) {
    isOpened = true;
    scrollDown.style.display = "none";
    openModal();
  }
});

modalButton.addEventListener("click", openModal);
closeButton.addEventListener("click", closeModal);

document.onkeydown = evt => {
  evt = evt || window.event;
  evt.keyCode === 27 ? closeModal() : false;
};