style.css

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {

    background: white;
    background: linear-gradient(90deg, rgba(2,0,36,1) 0%, rgba(9,9,121,1) 35%, rgba(0,212,255,1) 100%);
    color: white;
    font-family: "Times New Roman", Times serif;
    min-height: 100vh;
}
header{
    font-size: 1.5rem;
}

header, form{
    min-height: 20vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

form input, form button {
    padding: 0.5rem;
    font-size: 2rem;
    border: none;
    background: white;
}

form button{
     color: rgb(3, 81, 129);
     background: white;
     cursor: pointer;
     transition: all 0.3s ease-in;
}

form button:hover{
    background:rgb(13, 103, 158);
    color: white; 
}

.todo-container {
    display: flex;
    justify-content: center;
    justify-items: center;
}
.todo-list {
    min-width: 30%;
    list-style: none;
}

.todo {
    margin: 0.5rem;
    background: white;
    color: black;
    font-size: 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: all 0.3s ease; 
}
.todo li {
    flex: 1;
}

.trash-btn, .complete-btn{
    background: rgb(3, 81, 129);
    color: white;
    border: none;
    padding: 1rem;
    cursor: pointer;
    font-size: 1rem;
}
/* //13, 103, 158 / 49, 44, 139*/

.complete-btn{
    background: rgb(8, 128, 34);
}

.todo-item{
    padding: 0rem 0.5rem;
}

.fa-trash, .fa-check {
    pointer-events: none;
}

.completed {
    text-decoration: line-through;
    opacity: 0.5;
}

.drop{
    transform: translateX(5rem) rotateZ(25deg);
    opacity: 0;
}

select{
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    outline: none;
    border: none;
    color: rgb(15, 110, 168);
    width: 10rem;
    cursor: pointer;
    padding: 1rem;
}
.select {
    margin: 1rem;
    position: relative;
    overflow: hidden;
}
.select::after{
    content: "\25BC";
    position: absolute;
    background: rgb(3, 81, 129);
    top: 0;
    right: 0;
    padding: 1rem;
    pointer-events: none;
    transition: all 0.3s ease-in-out;
}
.select:hover::after{
    background: white;
    color: rgb(3, 81, 129);
}