style.css

:root{
  --main-color: #4a0ab2;
  --hover-color: rgb(107, 15, 255, 0.8);
}

body {
  font-family: 'Varela Round', sans-serif;  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-align: center;
  color: white;
  margin: 5vw;
  padding: 5vw;
  background-color: var(--main-color);
  transition: all .5s ease-in-out;
}

/* Top Nav */
#topLogo{
  display: inline;
}
.topnav{
  position: relative;
  text-align: center;
  padding-bottom: 5vw;
  margin: auto;
}
.topnav i{
  background-color: var(--hover-color);
  top: 2vw;
  right: 2vw;
  transition: all .5s ease-in-out;
}
#help{
  display: inline;
  float: right;
  padding: 2vw;
  position: relative;
  cursor: pointer;
}

/* Style the header */
.header {
  color: white;
  text-align: center;
}

/* Timer Navigation */
.timerNav{
  padding-top: 5vw;
}
.timerNav p{
  font-size: 16px;
  padding: 5px;
  color: white;
  text-decoration: none;
  display: inline;
}
.timerNav p.active{
  background-color: var(--main-color);
  border-radius: 10px;
  transition: all .5s ease-in-out;
}
.timerNav p:hover{
  text-decoration: underline;
  border-radius: 10px;
}
.timerNav p:hover.active{
  text-decoration: none;
}
/* Timer */
#timer{
  text-align: center;
  background-color: var(--hover-color);
  border-radius: 10px;
  transition: all .5s ease-in-out;
}

#timer button{
  text-decoration: none;
  color: var(--main-color);
  background-color: white;
  font-size: 16px;
  font-weight: bolder;
  margin-bottom: 5vw;
  padding: 1vw 2vw;
  transition: all .5s ease-in-out;
}
#clock{
  font-size: 100px;
  font-weight: bolder;
  margin: 5vw;
}

/* The switch - the box around the slider */
.switch {
  position: relative;
  display: block;
  visibility: hidden;
  width: 60px;
  height: 34px;
}

/* Hide default HTML checkbox */
.switch input {
  opacity: 0;
  width: 0;
  height: 0;
}

/* The slider */
.slider {
  position: absolute;
  visibility: hidden;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: #ccc;
  -webkit-transition: .4s;
  transition: .4s;
}

.slider:before {
  position: absolute;
  content: "";
  height: 26px;
  width: 26px;
  left: 4px;
  bottom: 4px;
  background-color: white;
  -webkit-transition: .4s;
  transition: .4s;
}

input:checked + .slider {
  background-color: #2196F3;
}

input:focus + .slider {
  box-shadow: 0 0 1px #2196F3;
}

input:checked + .slider:before {
  -webkit-transform: translateX(26px);
  -ms-transform: translateX(26px);
  transform: translateX(26px);
}

/* Rounded sliders */
.slider.round {
  border-radius: 34px;
}

.slider.round:before {
  border-radius: 50%;
}

/* Remove margins and padding from the list */
ul {
  margin: 0;
  padding: 0;
}

/* Style the list items */
ul li {
  cursor: pointer;
  position: relative;
  padding: 12px 8px 12px 35px;
  background: #eee;
  font-size: 16px;
  transition: 0.5s;
  list-style: none;
  color: var(--main-color);
  font-weight: bolder;
  text-align: left;


  /* make the list items unselectable */
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
}

/* Set all odd list items to a different color (zebra-stripes) */
ul li:nth-child(odd) {
  background: #f9f9f9;
}

/* Darker background-color on hover */
ul li:hover {
  background: #ddd;
}

/* When clicked on, add a background color and strike out text */
ul li.checked {
  background: #888;
  color: #fff;
  text-decoration: line-through;
}

/* Add a "checked" mark when clicked on */
ul li.checked::before {
  content: '';
  position: absolute;
  border-color: #fff;
  border-style: solid;
  border-width: 0 2px 2px 0;
  top: 10px;
  left: 16px;
  transform: rotate(45deg);
  height: 15px;
  width: 7px;
}

/* Style the close button */
.close {
  position: absolute;
  right: 0;
  top: 0;
  padding: 12px 16px 12px 16px;
}
.close:hover {
  background-color: #f44336;
  color: white;
}


/* Style the input */
input {
  margin-bottom: 2vw;
  border-color: white;
  border-width: 2px;  font-size: 20px;
  color: white;
  background-color: var(--main-color);
  transition: all .5s ease-in-out;
}
::placeholder{
  color: white;
}
#addBtn{
  text-decoration: none;
  border-color: white;
  border-width: 2px;
  color: white;
  background-color: var(--main-color);
  transition: all .5s ease-in-out;
  font-size: 16px;
}
/*Media Queries*/
@media screen and (max-width: 1980px){
  body{
    margin: 2vw;
  padding: 2vw;
  }
  #help{
    padding:1vw;
  }
  .topnav i{
    top: 1vw;
    right: 1vw;
  }
  #timer button{
    padding: .5vw 1vw;
  }
}



/* The Modal (background) */
.modal {
  display: none; 
  color:var(--main-color);
  position: fixed; 
  z-index: 1; 
  left: 0;
  top: 0;
  width: 100%; 
  height: 100%; 
  overflow: auto; 
  background-color: rgb(0,0,0); /* Fallback color */
  background-color: rgba(0,0,0,0.7); /* Black w/ opacity */
}

/* Modal Content/Box */
.modal-content {
  background-color: var(--main-color);
  margin: 15% auto; 
  padding: 20px;
  border: 1px solid #888;
  border-radius: 5px;
  width: 80%; 
}
.modal-content p{
  background-color: white;
  padding: 2vw;
  border-radius: 5px;
}
.modal-content h2{
  color: white;
  margin: 0;
}
.modal-content h4{
  color: white;
  margin: 0;
}