codepens/vacation-todo-list/dist/style.css

@import url("https://fonts.googleapis.com/css?family=Nunito:600,700&display=swap");
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
}

body {
  min-height: 450px;
  height: 100vh;
  margin: 0;
  background: radial-gradient(ellipse farthest-corner at center top, #f39264 0%, #f2606f 100%);
  color: #fff;
  font-family: 'Nunito', sans-serif;
}

button,
input,
select,
textarea {
  font-family: inherit;
  font-size: inherit;
  line-height: inherit;
}

/*-------------------- ToDo List -------------------*/
.todoList {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 320px;
  height: 500px;
  background: #fff;
  border-radius: 10px;
  box-shadow: 0 7px 30px rgba(62, 9, 11, 0.3);
}

/** Header Image **/
.cover-img .cover-inner {
  background: url("https://images.unsplash.com/photo-1516483638261-f4dbaf036963?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=1533&q=80");
  height: 190px;
  background-size: cover;
  background-position: 10% 20%;
  border-top-left-radius: 10px;
  border-top-right-radius: 10px;
  position: relative;
}
.cover-img .cover-inner::after {
  background: rgba(0, 0, 0, 0.3);
  content: "";
  top: 0;
  left: 0;
  position: absolute;
  width: 100%;
  height: 100%;
  border-top-left-radius: 10px;
  border-top-right-radius: 10px;
}
.cover-img .cover-inner h3 {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-family: 'Nunito', sans-serif;
  text-transform: uppercase;
  font-size: 2.8rem;
  z-index: 10;
  font-weight: 700;
}

/* Main Content */
.content {
  padding: 10px 20px;
}
.content form {
  display: flex;
  justify-content: space-between;
  margin-bottom: 15px;
  padding: 0 10px 0 5px;
  border-bottom: 1px solid #8e979c;
}
.content form > * {
  background: transparent;
  border: none;
  height: 35px;
}
.content input[type=text] {
  font-weight: 700;
  font-size: 1.2rem;
  color: #6C717B;
}
.content .input-buttons a {
  text-decoration: none;
}
.content .input-buttons i {
  margin-top: 5px;
  font-size: 20px;
  color: #8e979c;
}
.content ul.todos {
  margin-left: 0;
  padding: 0;
  list-style: none;
  height: 220px;
  overflow: auto;
}
.content li {
  user-select: none;
  margin-bottom: 10px;
  display: flex;
  justify-content: space-between;
}
.content li i {
  color: #6C717B;
  font-size: 15px;
  cursor: pointer;
  padding: 5px 10px;
}
.content input[type=checkbox] {
  display: none;
}
.content input[type=checkbox] + label {
  color: #6C717B;
  font-size: 15px;
  cursor: pointer;
  position: relative;
  border-radius: 3px;
  display: inline-block;
  padding: 5px 5px 5px 30px;
}
.content input[type=checkbox] + label:hover {
  color: #353A42;
  background-color: #F4F7FA;
}
.content input[type=checkbox] + label span.check {
  left: 4px;
  top: 50%;
  position: absolute;
  transform: translateY(-50%);
  width: 18px;
  height: 18px;
  display: block;
  background: white;
  border-radius: 3px;
  border: 1px solid #b8bfcc;
  box-shadow: 0 2px 3px #F0F4F8;
}
.content input[type=checkbox]:checked + label {
  color: #AEB7C6;
  text-decoration: line-through;
}
.content input[type=checkbox]:checked + label span.check {
  background-color: transparent;
  border-color: transparent;
  box-shadow: none;
}
.content input[type=checkbox] + label span.check::after {
  width: 100%;
  height: 100%;
  content: '';
  display: block;
  position: absolute;
  background-image: url("https://tjgillweb.github.io/Vacation-Todo-App/images/tick.svg");
  background-repeat: no-repeat;
  background-position: center;
  background-size: 16px 16px;
  transform: scale(0);
  transition: transform 300ms cubic-bezier(0.3, 0, 0, 1.5);
}
.content input[type=checkbox]:checked + label span.check::after {
  transform: scale(1);
}
.content input[type=checkbox] + label span.check::before {
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: block;
  content: '';
  position: absolute;
  border-radius: 50%;
  background: #8798AA;
  opacity: .8;
  transform: scale(0);
}
.content input[type=checkbox]:checked + label span.check::before {
  opacity: 0;
  transform: scale(1.3);
  transition: opacity 300ms cubic-bezier(0.2, 0, 0, 1), transform 400ms cubic-bezier(0.3, 0, 0, 1.4);
}