todo.css

body {
  font-family: 'Roboto Condensed', sans-serif;
  font-size: 20px;
  color: #444;
  border: 0;
  background-color: #e0f7fa;
}
h1 {
  font-family: 'Lemon', cursive;
  font-size: 44px;
  color: #00bfa5;
}

hr {
  border: 1px dashed #0097a7;
}

todo {
  display: block;
  max-width: 400px;
  margin: 5% auto;
}
timer {
  display: block;
  max-width: 400px;
  margin: 5% auto;
  font-size: small;
  color: #888;
}

form input {
  font-size: 100%;
  padding: .3em;
  border: 1px solid #ccc;
  border-radius: 0px;
}

button {
  background-color: #26a69a;
  border: 1px solid #00897b;
  font-size: 100%;
  color: #fff;
  padding: .3em .5em;
  cursor: pointer;
  margin: 0 0em;
  outline: none;
}

button[disabled] {
  background-color: #e0e0e0;
  border: 1px solid #bdbdbd;
  color: #aaa;
}

ul {
  padding: 0;
}

li {
  list-style-type: none;
  padding: .2em 0;
}

.completed {
  text-decoration: line-through;
  color: #ccc;
}

label {
  cursor: pointer;
}
/***************
   Checkboxes 
***************/
/* CUSTOM CSS CHECKBOXES */
form p {
  margin-bottom: 10px;
  text-align: left;
}

form p:last-child {
  margin-bottom: 0px;
}

/* Remove default checkbox */
[type="checkbox"]:not(:checked),
[type="checkbox"]:checked {
  position: absolute;
  left: -9999px;
}

[type="checkbox"]:not(:checked) + label,
[type="checkbox"]:checked + label {
  position: relative;
  padding-left: 35px;
  cursor: pointer;
  display: inline-block;
  height: 25px;
  line-height: 25px;
  font-size: 1rem;
  -webkit-user-select: none;
  /* webkit (safari, chrome) browsers */
  -moz-user-select: none;
  /* mozilla browsers */
  -khtml-user-select: none;
  /* webkit (konqueror) browsers */
  -ms-user-select: none;
  /* IE10+ */
}

/* checkbox aspect */
[type="checkbox"] + label:before {
  content: '';
  position: absolute;
  margin-top: 2px;
  left: 0;
  z-index: 0;
  -webkit-border-radius: 1px;
  -moz-border-radius: 1px;
  border-radius: 1px;
  background-clip: padding-box;
  -webkit-transition: 0.2s;
  -moz-transition: 0.2s;
  -o-transition: 0.2s;
  -ms-transition: 0.2s;
  transition: 0.2s;
}

/* Unchecked styles */
[type="checkbox"]:not(:checked) + label:before {
  top: 0px;
  width: 14px;
  height: 14px;
  border: 2px solid #5a5a5a;
}

/* Checked styles */
[type="checkbox"]:checked + label:before {
  left: -3px;
  top: -4px;
  width: 8px;
  height: 18px;
  border-top: 2px solid transparent;
  border-left: 2px solid transparent;
  border-right: 2px solid #0f9d58;
  border-bottom: 2px solid #0f9d58;
  -webkit-transform: rotateZ(40deg);
  -moz-transform: rotateZ(40deg);
  -ms-transform: rotateZ(40deg);
  -o-transform: rotateZ(40deg);
  transform: rotateZ(40deg);
  -webkit-backface-visibility: hidden;
  -webkit-transform-origin: 20% 40%;
  transform-origin: 100% 100%;
}

/* disabled checkbox */
[type="checkbox"]:disabled:not(:checked) + label:before,
[type="checkbox"]:disabled:checked + label:before {
  top: 0;
  left: 0;
  box-shadow: none;
  background-color: rgba(0, 0, 0, 0.26);
  width: 14px;
  height: 14px;
  border: 2px solid rgba(0, 0, 0, 0.26);
  -webkit-transform: rotateZ(0deg);
  -moz-transform: rotateZ(0deg);
  -ms-transform: rotateZ(0deg);
  -o-transform: rotateZ(0deg);
  transform: rotateZ(0deg);
}

[type="checkbox"]:disabled + label {
  color: rgba(0, 0, 0, 0.26);
}

[type="checkbox"]:disabled:not(:checked) + label:hover:before {
  border-color: rgba(0, 0, 0, 0.26);
}