style.css

* {
    font-family: 'Poppins', sans-serif;
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background: -webkit-linear-gradient(120deg, #FFEB3B, #2196F3);
    color: white;
    min-height: 100vh;
}


.container {
    display: flex;
    align-items: center;
    align-content: center;
    flex-direction: column;
}



header {
    font-size: 1.2rem;
    display: flex;
    align-items: center;
    align-content: center;
    flex-direction: column;
}

header,
form {
    margin-left: 11px;
    min-width: 20px;
    min-height: 20vh;
    justify-content: center;
    align-items: center;
    display: flex;
}


.todo-input {
    width: 370px;

}


form input,
form button {
    padding: .5rem;
    font-size: 2rem;
    border: none;
    background: white;
}

form button {
    color: #ffa502;
    background: white;
    cursor: pointer;
    transition: all 0.3s ease;
}


form button:hover {
    background: #ffa502;
    color: white;
}

.todo-container {
    display: flex;
    justify-content: center;
    align-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 0.5s ease;
}

.todo li {
    flex: 1;
}

.trash-btn,
.complete-btn {
    background: #ff4757;
    color: white;
    border: none;
    padding: 1rem;
    cursor: pointer;
    font-size: 1rem;
}

.complete-btn {
    background: rgb(73, 204, 73);
}

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

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

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

.fall {
    transform: translateY(8rem) rotateZ(20deg);
    opacity: 0;
}

select {
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    outline: none;
    border: none;

}

.select {
    margin: 1rem;
    position: relative;
    overflow: hidden;
    align-items: center;
    align-content: center;
    flex-direction: column;
}

select {
    color: #ffa502;
    width: 10rem;
    cursor: pointer;
    padding: 1rem;
}

.select::after {
    content: "\25BC";
    position: absolute;
    background: #ff4757;
    top: 0;
    right: 0;
    padding: 1rem;
    pointer-events: none;
    transition: all 0.3s ease;
}

.select:hover::after {
    background: white;
    color: #ff4757;
}