* {
    box-sizing: border-box;
    font-family: Arial, Helvetica, sans-serif;
}

body {
    background-color: #f2f2f2;
}

.content-center {
    width: 100%;
    max-width: 300px;
    margin: auto;
    padding: 20px;
    background-color: #fff;
    border-radius: 15px;
}

.content-center .text-center {
    text-align: center;
}

.content-center img {
    width: 70%;
}

.content-center form {
    margin: 20px;
}

.content-center input,
.content-center button {
    width: 100%;
    padding: 10px 5px;
    border: none;
    outline: none;
}

.content-center input {
    border-bottom-color: #ccc;
    border-bottom-style: solid;
    border-bottom-width: 2px;
    margin-bottom: 10px;
}

.content-center input:focus {
    border-bottom-color: #d07335;
}

.content-center button {
    background-color: #d07335;
    color: #fff;
}

.content-center button:hover {
    background-color: #b55b28;
    cursor: pointer;  
}

.content-center button:active {
    background-color: #c14e0e;
}

header a {
    color: #666;
    text-decoration: none;
}

header a:visited {
    color: #000;
}

header a:hover {
    text-decoration: underline;
}

header a:focus {
    color: red;
}

header a:active {
    color: yellow;
}

header h1 {
    font-size: 2.5em;
    text-align: center;
    margin: 50px auto;
}

footer {
    font-size: .8em;
    text-align: center
}

.content-tabuada {
    width: 100%;
    text-align: center;
    max-width: 500px;
    background-color: #fff;
    margin: auto;
    padding: 20px;
    border-radius: 20px;
}

.content-tabuada table {
    width: 100%;
    border-collapse: collapse;
}

.content-tabuada td {
    padding: .75rem;
    border-top: 1px solid #dee2e6;
}

.content-tabuada tbody tr:nth-child(odd) {
    background-color: rgba(0,0,0, .05);
}

.content-tabuada tbody tr:hover {
    background-color: rgba(0,0,0, .015);
    cursor: pointer;
}

#valorA {
    width: 100%;
    padding: 10px;
    background-color: aquamarine;
}

.todo {
    list-style: none;
    padding: 0;
}

.todo li {
    padding: 10px;
    border-bottom: #ccc 1px solid;
}

.todo li input {
    width: initial;
    margin-right: 10px;
    
}

.todo li.complete {
    text-decoration: line-through;
    color: #999;
    cursor: not-allowed;        
}