todo-style

app.scss

#todo-app {
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  margin: 60px auto;
  max-width: 320px;
  padding: 38px;
  font-size: 16px;
  color: rgba(0, 0, 0, 0.8);
  box-shadow:
    /* The top layer shadow */
    0px 1px 2px rgba(0, 0, 0, 0.18),
    0px 1px 10px rgba(0, 0, 0, 0.15),
    /* The second layer */
    0 10px 0 -5px #eee,
    /* The second layer shadow */
    0 10px 1px -4px rgba(0,0,0,0.15),
     /* The third layer */
    0 20px 0 -10px #eee,
    /* The third layer shadow */
    0 20px 1px -9px rgba(0,0,0,0.15);
    /* Padding for demo purposes */
    padding: 30px;

  ul {
    list-style-type: none;
    padding: 0;
    margin: 0;
    margin-bottom: 43px;
  }

  li {
    margin: 26px 0;

    p {
      display: inline;
      cursor: pointer;
      position: relative;
      &::after {
        content: "";
        position: absolute;
        left: 0;
        width: 100%;
        height: 2px;
        top: 10px;
        background-color: rgb(45, 45, 45);
        width: 0%;
        transition: width 0.3s;
      }

      &:hover,
      &[data-checked] {
        opacity: 0.5;
      }

      &[data-checked]::after {
        width: 100%;
      }
    }

    button {
      margin-top: -5px;
      background-color: #de6b58;
      opacity: 0;
      transition: opacity 0.1s;
    }

    &:hover button {
      opacity: 0.5;
      &:hover {
        opacity: 1;
      }
    }
  }

  button {
    border: none;
    border-radius: 2px;
    padding: 6px 8px;
    font-size: 14px;
    color: white;
    box-shadow: 0px 1px 3px rgba(0, 0, 0, 0.08);
    cursor: pointer;
    transition: box-shadow 0.1s, transform 0.1s;
    float: right;
    &:hover {
      box-shadow: 0px 1px 5px rgba(0, 0, 0, 0.15);
      transform: scale(1.02);
    }
    &:focus {
      outline: none;
    }
  }

  input {
    outline: none;
    border: none;
    border-bottom: 1px solid rgba(0, 0, 0, 0.38);
    width: calc(100% - 110px);
    font-size: 16px;
    padding: 5px 0px;
    &:focus {
      border-color: rgba(21, 124, 230, 0.72);
    }

    + button {
      width: 90px;
      margin-top: 2px;
      background-color: #41daa1;
    }
  }
}