* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 0;
  background-color: #e5efff;
  color: #4e5e72;
  text-align: center;
  font-family: 'Montserrat', sans-serif;
  overflow: hidden;
}

h1,
p {
  margin: 0;
  padding: 0;
}

h1 {
  font-size: 2rem;
  font-family: 'Montserrat', sans-serif;
}

small {
  display: block;
  padding: 1rem 0;
  font-size: 0.8rem;
  transition: opacity 0.33s;
}

textarea,
input,
button {
  line-height: 1.5rem;
  border: 0;
  outline: none;
  font-family: inherit;
  appearance: none;
}

textarea,
input {
  color: #4e5e72;
  background-color: transparent;
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='10' height='24'><rect fill='rgb(229, 225, 187)' x='0' y='23' width='10' height='1'/></svg>");
}

textarea {
  width: 100%;
  height: 8rem;
  resize: none;
}

input {
  width: 50%;
  margin-bottom: 1rem;
}
input[type="text"]:invalid,
input [type="email"]:invalid {
  box-shadow: none;
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='10' height='24'><rect fill='rgba(240, 132, 114, 0.5)' x='0' y='23' width='10' height='1'/></svg>");
}

button {
  padding: 0.5rem 1rem;
  border-radius: 0.25rem;
  background-color: #3f51b5;
  color: white;
  font-size: 1rem;
  text-align: center;
  outline: none;
  transition: background-color 0.2s;
}

input[type="text"]:focus,
input[type="email"]:focus,
textarea:focus {
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='10' height='24'><rect fill='rgba(78, 94, 114, 0.3)' x='0' y='23' width='10' height='1'/></svg>");
  outline: none;
}

.letter {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  width: 30rem;
  margin: auto;
  perspective: 60rem;
}

@media (max-width: 800px) {
  .letter {
    width: 20rem;
  }
}

.side {
  height: 12rem;
  background-color: #fcfcf8;
  outline: 1px solid transparent;
}
.side:nth-of-type(1) {
  padding: 2rem 2rem 0;
  border-radius: 1rem 1rem 0 0;
  box-shadow: inset 0 0.75rem 4rem rgba(229, 225, 187, 1);
}
.side.side:nth-of-type(2) {
  padding: 2rem;
  border-radius: 0 0 1rem 1rem;
  box-shadow: 0 0.3rem 0.3rem rgba(0, 0, 0, 0.05),
    inset 0 -0.57rem 4rem rgba(229, 225, 187, 1);
  text-align: left;
}

.envelope {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  margin: auto;
}

.envelope.front {
  width: 10rem;
  height: 6rem;
  border-radius: 0 0 1rem 1rem;
  overflow: hidden;
  z-index: 7;
  opacity: 0;
}

.envelope.front::before,
.envelope.front::after {
  position: absolute;
  display: block;
  width: 12rem;
  height: 6rem;
  background-color: #e9dc9d;
  transform: rotate(30deg);
  transform-origin: 0 0;
  box-shadow: 0 0 1rem rgba(0, 0, 0, 0.1);
  content: "";
}

.envelope.front::after {
  right: 0;
  transform: rotate(-30deg);
  transform-origin: 100% 0;
}

.envelope.back {
  top: -4rem;
  width: 10rem;
  height: 10rem;
  overflow: hidden;
  z-index: -9998;
  opacity: 0;
  transform: translateY(-6rem);
}
.envelope.back::before {
  display: block;
  width: 10rem;
  height: 10rem;
  background-color: #e9dc9d;
  border-radius: 1rem;
  content: "";
  transform: scaleY(0.6) rotate(45deg);
}

.result-message {
  opacity: 0;
  transition: all 0.3s 2s;
  transform: translateY(9rem);
  z-index: -9999;
}

.sent .letter {
  animation: scaleLetter 1s forwards ease-in;
}
.sent .side:nth-of-type(1) {
  transform-origin: 0 100%;
  animation: closeLetter 0.66s forwards ease-in;
}
.sent .side:nth-of-type(1) h1,
.sent .side:nth-of-type(1) textarea {
  animation: fadeOutText 0.66s forwards linear;
}
.sent button {
  background-color: rgba(78, 94, 114, 0.2);
}
.sent .envelope {
  animation: fadeInEnvelope 0.5s 1.33s forwards ease-out;
}
.sent .result-message {
  opacity: 1;
  transform: translateY(12rem);
}
.sent small {
  opacity: 0;
}

.centered {
  position: absolute;
  left: 0;
  right: 0;
  margin: 1rem auto;
}

@keyframes closeLetter {
  50% {
    transform: rotateX(-90deg);
  }
  100% {
    transform: rotateX(-180deg);
  }
}
@keyframes fadeOutText {
  49% {
    opacity: 1;
  }
  50% {
    opacity: 0;
  }
  100% {
    opacity: 0;
  }
}
@keyframes fadeInEnvelope {
  0% {
    opacity: 0;
    transform: translateY(8rem);
  }
  /*90% {opacity: 1; transform: translateY(4rem);}*/
  100% {
    opacity: 1;
    transform: translateY(4.5rem);
  }
}
@keyframes scaleLetter {
  66% {
    transform: translateY(-8rem) scale(0.5, 0.5);
  }
  75% {
    transform: translateY(-8rem) scale(0.5, 0.5);
  }
  90% {
    transform: translateY(-8rem) scale(0.3, 0.5);
  }
  97% {
    transform: translateY(-8rem) scale(0.33, 0.5);
  }
  100% {
    transform: translateY(-8rem) scale(0.3, 0.5);
  }
}

/* Header Styles */

header {
  position: relative;
  width: 100%;
  display: flex;
  justify-content: flex-start;
  align-items: center;
  padding: 18px 100px;
  opacity: 0;
  color: #fff;
  z-index: 1;
  background-color: rgba(0, 0, 0, 0.8);
  border-radius: 0 0 85% 85% / 40%;
  margin-bottom: 25px;
  animation: fadein 1s 0.5s forwards;
}

@keyframes fadein {
  100% {
    opacity: 1;
  }
}

header nav {
  display: flex;
  margin-right: -15px;
}

header nav li {
  margin: 0 15px;
  list-style: none;
}

header nav li a {
  opacity: 1;
  font-size: 20px;
  text-decoration: none;
  color: #fff;
}

@media (max-width: 1000px) {
  header {
    justify-content: center;
  }
}

/* MOBILE HAMBURGER MENU */
/* Don't display on web page */
@media (min-width: 600px) {
  .hamburger {
    display: none;
  }
}
/* Basic Styles */
@media (max-width: 600px) {
  header {
    display: none;
  }

  /* Basic Styles */
  .hamburger {
    position: relative;
    z-index: 8;
    opacity: 0;
    animation: fadein 1s 0.5s forwards;
    display: flex;
    justify-content: flex-start;
    margin-bottom: 50px;
  }

  /* Toggle Functionality */
  #toggle {
    display: none;
  }

  #toggle:checked ~ .toggle-container .button-toggle {
    box-shadow: 0 0 0 550px rgba(0, 0, 0, 0.9),
      inset 0 0 0 20px rgba(0, 0, 0, 0.9);
  }

  #toggle:checked ~ .toggle-container .button-toggle {
    border-radius: 1%;
  }

  #toggle:checked ~ .toggle-container .button-toggle:before {
    transform: translateY(-50%) rotate(45deg) scale(1);
  }

  #toggle:checked ~ .toggle-container .button-toggle:after {
    transform: translateY(-50%) rotate(-45deg) scale(1);
  }

  #toggle:checked ~ .nav {
    margin-bottom: 100px;
    pointer-events: auto;
    transform: translate(50px, 50px);
  }

  #toggle:checked ~ .nav .nav-item {
    z-index: 8;
    color: #fff;
    letter-spacing: 0;
    height: 40px;
    line-height: 40px;
    margin-top: 0;
    opacity: 1;
    transform: scaleY(1);
    transition: 0.5s, opacity 0.1s;
  }

  #toggle:checked ~ .nav .nav-item:nth-child(1) {
    transition-delay: 0.2s;
  }

  #toggle:checked ~ .nav .nav-item:nth-child(1):before {
    transition-delay: 0.2s;
  }

  #toggle:checked ~ .nav .nav-item:nth-child(2) {
    transition-delay: 0.15s;
  }

  #toggle:checked ~ .nav .nav-item:nth-child(2):before {
    transition-delay: 0.15s;
  }

  #toggle:checked ~ .nav .nav-item:nth-child(3) {
    transition-delay: 0.1s;
  }

  #toggle:checked ~ .nav .nav-item:nth-child(3):before {
    transition-delay: 0.1s;
  }

  #toggle:checked ~ .nav .nav-item:nth-child(4) {
    transition-delay: 0.05s;
  }

  #toggle:checked ~ .nav .nav-item:nth-child(4):before {
    transition-delay: 0.05s;
  }

  #toggle:checked ~ .nav .nav-item:nth-child(5) {
    transition-delay: 0s;
  }

  #toggle:checked ~ .nav .nav-item:nth-child(5):before {
    transition-delay: 0s;
  }

  #toggle:checked ~ .nav .nav-item:before {
    opacity: 0;
  }

  /* Toggle Button */
  .button-toggle {
    position: absolute;
    display: inline-block;
    width: 25px;
    height: 25px;
    margin: 25px;
    border-radius: 100%;
    background-color: transparent;
    border: none;
    cursor: pointer;
    transition: 0.6s;
    box-shadow: 0 0 0 16px rgb(0, 0, 0), inset 0 0 0 20px rgb(0, 0, 0);
  }

  .button-toggle:before,
  .button-toggle:after {
    position: absolute;
    content: "";
    top: 50%;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: #000a1d;
    border-radius: 1%;
    transition: 0.5s;
  }

  .button-toggle::before,
  .button-toggle::after {
    background-color: white;
    border-radius: 0%;
  }

  .button-toggle:before {
    transform: translateY(-50%) rotate(45deg) scale(0);
  }
  .button-toggle:after {
    transform: translateY(50%) rotate(-45deg) scale(0);
  }

  /* Menu */
  .nav {
    display: inline-block;
    margin: 25px 25px 20px;
    pointer-events: none;
    transition: 0.5s;
  }
  .nav-item {
    position: relative;
    float: left;
    clear: both;
    color: rgba(0, 0, 0, 0.9);
    font-size: 18px;
    letter-spacing: -6.2px;
    height: 7px;
    line-height: 7px;
    text-transform: uppercase;
    white-space: nowrap;
    transform: scaleY(0.2);
    transition: 0.5s, opacity 1s;
  }

  .nav-item:nth-child(1) {
    transition-delay: 0s;
  }

  .nav-item:nth-child(1):before {
    transition-delay: 0s;
  }

  .nav-item:nth-child(2) {
    transition-delay: 0.05s;
  }

  .nav-item:nth-child(2):before {
    transition-delay: 0.05s;
  }

  .nav-item:nth-child(3) {
    transition-delay: 0.1s;
  }

  .nav-item:nth-child(3):before {
    transition-delay: 0.1s;
  }

  .nav-item:nth-child(4) {
    transition-delay: 0.15s;
  }

  .nav-item:nth-child(4):before {
    transition-delay: 0.15s;
  }

  .nav-item:nth-child(5) {
    transition-delay: 0.2s;
  }

  .nav-item:nth-child(5):before {
    transition-delay: 0.2s;
  }

  .nav-item:nth-child(1) {
    letter-spacing: -8px;
  }

  .nav-item:nth-child(2) {
    letter-spacing: -7px;
  }

  .nav-item:nth-child(n + 4) {
    letter-spacing: -8px;
    margin-top: -7px;
    opacity: 0;
  }

  .nav-item:before {
    position: absolute;
    content: "";
    top: 50%;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: white;
    transform: translateY(-50%) scaleY(5);
    transition: 0.5s;
  }
}