style.css

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

body {
    margin: 5% 5%;
    background-color: #7a1ae1;
}
header {
    display: flex;
    justify-content: center;
    align-items: center;
}
h1 {
    color: #fff;
    font-size: 35px;
}
main {
    display: flex;
    justify-content: center;
    align-items: center;
}

footer {
    display: flex;
    justify-content: center;
    align-items: center;
    color: #fff;
    font-size: 15px;
}

input {
    font-size: 20px;
    color: #41183c;
    width: 82%;
    height: 50px;
    border-radius: 10px;
    
    padding: 2px 12px;
    margin: 2px;
    outline: none;
}

button {
    width: 40px;
    height: 40px;
    border-radius: 10px;
    margin: 3px 3px;
    font-weight: bold;
    background-color: #fff;
    transition: 0.5s;
    border: none;
    cursor: pointer;
}

button:hover {
    background-color: #970484;
    color: #fff;
}

ul {
    display: flex;
    flex-direction: column;
    justify-content: center;
    width: 100%;
}

li {
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-radius: 10px;
    background-color: #fff;
    color: #41183c;
    font-weight: bold;
    font-size: 25px;
    padding: 12px;
    margin: 5px 5px;
}

.conteudo {
    max-width: 600px;
    margin-top: 50px;
    margin-bottom: 10%;
    background-color: #e70dbf;
    border-radius: 10px;
}

.input-tarefa {
    margin: 10px;
}

.tarefa {
    width: 100%;
    padding: 5px;
}