* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
  font-family: Arial, Helvetica, sans-serif;
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  background: black;
  height: 100vh;
}

div {
  width: 400px;
  display: flex;
  flex-direction: column;
  align-items: center;
}

form {
  display: flex;
  align-items: center;
  justify-content: center;
}

h1 {
  color: orangered;
  margin-bottom: 10px;
}
#input {
  height: 40px;
  font-size: 24px;
  width: 100%;
  padding: 2px 10px;
  background: rgba(255, 68, 0, 0.157);
  color: rgba(255, 255, 255, 0.602);
  cursor: pointer;
  border: none;
  border-bottom: orangered 2px solid;
  display: none;
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.5s ease-in;
}
#input.active {
  display: block;
  transform: scaleX(100%);
}

#input:focus {
  outline: none;
}
#input::placeholder {
  color: rgba(255, 68, 0, 0.26);
  font-size: 15px;
}

#btn {
  transition: all 10ms ease-in;
  height: 40px;
  width: 40px;
  border-radius: 50%;
  background-color: transparent;
  color: orangered;
  border: 2px solid orangered;
  font-size: 30px;
  cursor: pointer;
}
#btn.active {
  border-radius: 0;
  height: 40px;
  font-size: 15px;
  width: fit-content;
  padding: 2px;
  background-color: black;
  font-weight: 700;
  margin-left: 5px;
}

#btn:hover {
  background-color: rgba(255, 68, 0, 0.26);
}

ul {
  width: 100%;
  display: flex;
  flex-direction: column;
  text-align: center;
  margin-top: 10px;
  padding: 0 10px;
  list-style: none;
}

ul li {
  width: 100%;
  color: rgba(255, 68, 0, 0.746);
  height: fit-content;
  background-color: rgba(255, 68, 0, 0.205);
  padding: 5px;
  min-height: 40px;
  display: grid;
  place-items: center;
  margin-bottom: 5px;
  font-weight: 600;
}

ul li.completed {
  background-color: rgba(255, 255, 255, 0.089);
  color: rgba(255, 68, 0, 0.294);
}