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

#container {
    padding: 50px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    font-family: Arial, Helvetica, sans-serif;
    background: rgba(13, 79, 122, 0.116);
}

h1 {
    font-size: 4rem;
    color: #fff;
    text-align: center;
    text-shadow: 2px 2px 5px rgba(0, 0, 0, 0.431);
}

#form-todo {
    margin-top: 50px
} 

#input-todo {
    padding: 0 12px;
    height: 2.5rem;
    font-size: 1.2rem;
    border-radius: 10px;
    border: 1px solid #ccc;
    outline: none
}

#add-btn {
    width: 4rem;
    height: 2.5rem;
    line-height: 2.5rem;
    font-size: 1.2rem;
    letter-spacing: 1px;
    font-weight: bold;
    color: #fff;
    background: rgb(39, 149, 212);
    border: none;
    border-radius: 10px;
    cursor: pointer;
    margin: 0 8px;
}

#add-btn:active {
    transform: scale(1.1);
}

#select {
    display: inline-block;
    position: relative
}

.filter-todo {
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    width: 10rem;
    height: 2.5rem;
    padding: 0 10px;
    font-size: 1.2rem;
    font-weight: bold;
    background: rgb(39, 149, 212);
    color: #fff /* rgb(167, 164, 164) */;
    border-radius: 10px;
    border: none;
    cursor: pointer;
    outline: none;
}

#select::after {
    content: "\25BC";
    color: #fff;
    position: absolute;
    top: 50%;
    right: 10px;
    transform: translateY(-50%);
    cursor: pointer;
    pointer-events: none;
}

#todo-list {
    width: 400px;
    list-style-type: none;
    list-style-position: inside;
    margin: 50px 0;
    background: #fff;
    border-radius: 10px;
    box-shadow: 2px 2px 3px rgba(0, 0, 0, 0.404)
}

.todo {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px;
}

.todo-item {
    flex: 1;
    font-size: 1.2rem;
    transition: all 0.5s ease;
}

.checked {
    text-decoration: line-through;
    font-weight: bold;
    transition: all 0.2s ease-in;
    text-shadow: 0px 3px 5px #ccc;
    opacity: 0.4
}

.check-btn {
    width: 25px;
    height: 25px;
    line-height: 25px;
    font-size: 1.1rem;
    font-weight: bold;
    color: #fff;
    background: rgb(102, 175, 18);
    border-radius: 10px;
    border: none;
    cursor: pointer;
}

.delete-btn {
    width: 25px;
    height: 25px;
    line-height: 25px;
    margin-left: 10px;
    font-size: 1.1rem;
    font-weight: bold;
    color: #fff;
    background: rgb(192, 42, 42);
    border-radius: 10px;
    border: none;
    cursor: pointer;
}

.delete-btn:hover, .done-btn:hover {
    box-shadow: 1px 0px 2px rgba(0, 0, 0, 0.479)
}

@media screen and (max-width: 620px) {
    #form-todo {
        text-align: center;
    }

    h1 {
        font-size: 3rem;
    }

    #input-todo {
        width: 80%
    }

    #add-btn {
        width: 18%;
        margin: 0
    }

    #select, .filter-todo {
        display: none
    }

    #todo-list {
        width: 100%
    }
}

@media screen and (max-width: 360px) {
    #input-todo {
        width: 100%;
    }

    #add-btn {
        width: 100%;
        margin-top: 6px
    }
}