Bootstrap 4 - Flex
Descrição
O utilitário Flex pode ser usado para gerenciar o layout, alinhamento, colunas de grade, navegação e outros componentes da página. Facilita o projeto da estrutura de layout sem usar flutuação ou posicionamento.
Flex Behaviors and Direction
Use os utilitários de exibição do flexbox como d-flex e d-inline-flex para exibir o contêiner flexbox e os elementos filhos em itens flex. Você pode definir a direção dos itens flex na direção horizontal e na direção vertical usando .flex-row (use .flex-row-reverse para exibir a direção horizontal do lado oposto) e .flex-column (use .flex-column-reverse para exibir a direção vertical do lado oposto) classes, respectivamente, conforme mostrado no exemplo abaixo -
Exemplo
<html>
<head>
<!-- Meta tags -->
<meta charset = "utf-8">
<meta name = "viewport" content = "width = device-width, initial-scale = 1, shrink-to-fit = no">
<!-- Bootstrap CSS -->
<link rel = "stylesheet"
href = "https://maxcdn.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css">
<title>Bootstrap 4 Example</title>
</head>
<body>
<div class = "container">
<h2>Flex Behaviors</h2>
<div class = "d-flex p-2 bg-info">
This is flex container, uses the 'd-flex' class
</div>
<br>
<div class = "d-inline-flex p-2 bg-info">
This is inline flexbox container, uses the 'd-inline-flex' class
</div>
<br>
<br>
<h2>Direction</h2>
<h4>Horizontal Direction</h4>
<div class = "d-flex flex-row bg-info mb-3">
<div class = "p-2 border border-dark ">flex-row: Item 1</div>
<div class = "p-2 border border-dark">flex-row: Item 2</div>
<div class = "p-2 border border-dark">flex-row: Item 3</div>
</div>
<div class = "d-flex flex-row-reverse bg-info">
<div class = "p-2 border border-dark">flex-row-reverse: Item 1</div>
<div class = "p-2 border border-dark">flex-row-reverse: Item 2</div>
<div class = "p-2 border border-dark">flex-row-reverse: Item 3</div>
</div>
<br>
<h4>Vertical Direction</h4>
<div class = "d-flex flex-column bg-info mb-3">
<div class = "p-2 border border-dark">flex-column: Item 1</div>
<div class = "p-2 border border-dark">flex-column: Item 2</div>
<div class = "p-2 border border-dark">flex-column: Item 3</div>
</div>
<div class = "d-flex flex-column-reverse bg-info">
<div class = "p-2 border border-dark">flex-column-reverse: Item 1</div>
<div class = "p-2 border border-dark">flex-column-reverse: Item 2</div>
<div class = "p-2 border border-dark">flex-column-reverse: Item 3</div>
</div>
</div>
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src = "https://code.jquery.com/jquery-3.2.1.slim.min.js"
integrity = "sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN"
crossorigin = "anonymous">
</script>
<!-- Popper -->
<script src = "https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js"
integrity = "sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q"
crossorigin = "anonymous">
</script>
<!-- Latest compiled and minified Bootstrap JavaScript -->
<script src = "https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"
integrity = "sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl"
crossorigin = "anonymous">
</script>
</body>
</html>Isso produzirá o seguinte resultado -
Resultado
Justificar conteúdo
O alinhamento dos itens flexíveis (como início, fim, centro, entre e ao redor) pode ser alterado no eixo principal (eixo x para início) dos contêineres flexbox usando o utilitário justify-content .
O exemplo a seguir demonstra isso -
Exemplo
<html>
<head>
<!-- Meta tags -->
<meta charset = "utf-8">
<meta name = "viewport" content = "width = device-width, initial-scale = 1, shrink-to-fit = no">
<!-- Bootstrap CSS -->
<link rel = "stylesheet"
href = "https://maxcdn.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css">
<title>Bootstrap 4 Example</title>
</head>
<body>
<div class = "container">
<h2>Alignment - Start</h2>
<div class = "d-flex justify-content-start bg-info">
<div class = "p-2 border border-dark">Item 1</div>
<div class = "p-2 border border-dark">Item 2</div>
<div class = "p-2 border border-dark">Item 3</div>
</div>
<br>
<h2>Alignment - End</h2>
<div class = "d-flex justify-content-end bg-info">
<div class = "p-2 border border-dark">Item 1</div>
<div class = "p-2 border border-dark">Item 2</div>
<div class = "p-2 border border-dark">Item 3</div>
</div>
<br>
<h2>Alignment - Center</h2>
<div class = "d-flex justify-content-center bg-info">
<div class = "p-2 border border-dark">Item 1</div>
<div class = "p-2 border border-dark">Item 2</div>
<div class = "p-2 border border-dark">Item 3</div>
</div>
<br>
<h2>Alignment - Between</h2>
<div class = "d-flex justify-content-between bg-info">
<div class = "p-2 border border-dark">Item 1</div>
<div class = "p-2 border border-dark">Item 2</div>
<div class = "p-2 border border-dark">Item 3</div>
</div>
<br>
<h2>Alignment - Around</h2>
<div class = "d-flex justify-content-around bg-info">
<div class = "p-2 border border-dark">Item 1</div>
<div class = "p-2 border border-dark">Item 2</div>
<div class = "p-2 border border-dark">Item 3</div>
</div>
</div>
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src = "https://code.jquery.com/jquery-3.2.1.slim.min.js"
integrity = "sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN"
crossorigin = "anonymous">
</script>
<!-- Popper -->
<script src = "https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js"
integrity = "sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q"
crossorigin = "anonymous">
</script>
<!-- Latest compiled and minified Bootstrap JavaScript -->
<script src = "https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"
integrity = "sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl"
crossorigin = "anonymous">
</script>
</body>
</html>Isso produzirá o seguinte resultado -
Resultado
Alinhar itens
O alinhamento dos itens flexíveis (como início, fim, centro, linha de base e extensão) pode ser alterado no eixo cruzado (eixo y para iniciar) dos contêineres flexbox usando o utilitário de itens de alinhamento .
O exemplo a seguir demonstra isso -
Exemplo
<html>
<head>
<!-- Meta tags -->
<meta charset = "utf-8">
<meta name = "viewport" content = "width = device-width, initial-scale = 1, shrink-to-fit = no">
<!-- Bootstrap CSS -->
<link rel = "stylesheet"
href = "https://maxcdn.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css">
<title>Bootstrap 4 Example</title>
</head>
<body>
<div class = "container">
<h2>Align Items - Start</h2>
<div class = "d-flex align-items-start bg-info" style = "height: 100px">
<div class = "p-2 border border-dark">Item 1</div>
<div class = "p-2 border border-dark">Item 2</div>
<div class = "p-2 border border-dark">Item 3</div>
</div>
<br>
<h2>Align Items - End</h2>
<div class = "d-flex align-items-end bg-info" style = "height: 100px">
<div class = "p-2 border border-dark">Item 1</div>
<div class = "p-2 border border-dark">Item 2</div>
<div class = "p-2 border border-dark">Item 3</div>
</div>
<br>
<h2>Align Items - Center</h2>
<div class = "d-flex align-items-center bg-info" style = "height: 100px">
<div class = "p-2 border border-dark">Item 1</div>
<div class = "p-2 border border-dark">Item 2</div>
<div class = "p-2 border border-dark">Item 3</div>
</div>
<br>
<h2>Align Items - Baseline</h2>
<div class = "d-flex align-items-baseline bg-info" style = "height: 100px">
<div class = "p-2 border border-dark">Item 1</div>
<div class = "p-2 border border-dark">Item 2</div>
<div class = "p-2 border border-dark">Item 3</div>
</div>
<br>
<h2>Align Items - Stretch</h2>
<div class = "d-flex align-items-stretch bg-info" style = "height: 100px">
<div class = "p-2 border border-dark">Item 1</div>
<div class = "p-2 border border-dark">Item 2</div>
<div class = "p-2 border border-dark">Item 3</div>
</div>
<br>
</div>
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src = "https://code.jquery.com/jquery-3.2.1.slim.min.js"
integrity = "sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN"
crossorigin = "anonymous">
</script>
<!-- Popper -->
<script src = "https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js"
integrity = "sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q"
crossorigin = "anonymous">
</script>
<!-- Latest compiled and minified Bootstrap JavaScript -->
<script src = "https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"
integrity = "sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl"
crossorigin = "anonymous">
</script>
</body>
</html>Isso produzirá o seguinte resultado -
Resultado
Preencher, crescer e encolher
Os elementos podem ser exibidos em larguras iguais no espaço horizontal usando a classe .flex-fill . O item flexível aumentará, se houver espaço disponível usando a classe .flex-grow- * e o item flexível encolherá, se necessário, usando a classe .flex-shrink- * .
O exemplo a seguir demonstra o uso dos utilitários acima -
Exemplo
<html>
<head>
<!-- Meta tags -->
<meta charset = "utf-8">
<meta name = "viewport" content = "width = device-width, initial-scale = 1, shrink-to-fit = no">
<!-- Bootstrap CSS -->
<link rel = "stylesheet"
href = "https://maxcdn.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css">
<title>Bootstrap 4 Example</title>
</head>
<body>
<div class = "container">
<h2>Fill</h2>
<div class = "d-flex bg-info">
<div class = "p-2 flex-fill border border-dark">Item 1</div>
<div class = "p-2 flex-fill border border-dark">Item 2</div>
<div class = "p-2 flex-fill border border-dark">Item 3</div>
</div>
<br>
<h2>Grow</h2>
<div class = "d-flex bg-info">
<div class = "p-2 flex-grow-1 bg-info">Item 1 (Using class flex-grow-1)</div>
<div class = "p-2 bg-warning">Item 2</div>
<div class = "p-2 bg-secondary">Item 3</div>
</div>
<br>
<h2>Shrink</h2>
<div class = "d-flex bg-info">
<div class = "p-2 w-100 bg-info">Item 1</div>
<div class = "p-2 flex-shrink-1 bg-warning">Item 2 (Using class flex-shrink-1)</div>
</div>
</div>
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src = "https://code.jquery.com/jquery-3.2.1.slim.min.js"
integrity = "sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN"
crossorigin = "anonymous">
</script>
<!-- Popper -->
<script src = "https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js"
integrity = "sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q"
crossorigin = "anonymous">
</script>
<!-- Latest compiled and minified Bootstrap JavaScript -->
<script src = "https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"
integrity = "sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl"
crossorigin = "anonymous">
</script>
</body>
</html>Isso produzirá o seguinte resultado -
Resultado
Margens automáticas e com itens de alinhamento
O utilitário flex fornece o recurso de margem automática nos itens flex usando as classes .mr-auto (empurra itens para a direita) e .ml-auto (empurra itens para a esquerda). Os itens flex podem ser movidos para cima ou para baixo usando as classes mt-auto ou mb-auto em um contêiner.
O exemplo a seguir demonstra o uso das classes acima -
Exemplo
<html>
<head>
<!-- Meta tags -->
<meta charset = "utf-8">
<meta name = "viewport" content = "width = device-width, initial-scale = 1, shrink-to-fit = no">
<!-- Bootstrap CSS -->
<link rel = "stylesheet"
href = "https://maxcdn.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css">
<title>Bootstrap 4 Example</title>
</head>
<body>
<div class = "container">
<h2>Auto Margins</h2>
<div class = "d-flex bg-info mb-3">
<div class = "p-2 bg-warning">Item 1</div>
<div class = "p-2 bg-primary">Item 2</div>
<div class = "p-2 bg-secondary">Item 3</div>
</div>
<div class = "d-flex bg-info mb-3">
<div class = "mr-auto p-2 bg-warning">mr-auto: Item 1</div>
<div class = "p-2 bg-primary">Item 2</div>
<div class = "p-2 bg-secondary">Item 3</div>
</div>
<div class = "d-flex bg-info mb-3">
<div class = "p-2 bg-secondary">Item 1</div>
<div class = "p-2 bg-primary">Item 2</div>
<div class = "ml-auto p-2 bg-warning">ml-auto: Item 3</div>
</div>
<h2>With align-items</h2>
<div class = "d-flex align-items-start flex-column bg-info mb-3"
style = "height: 200px;">
<div class = "mb-auto p-2 bg-warning">mb-auto: Item 1</div>
<div class = "p-2 bg-primary">Item 2</div>
<div class = "p-2 bg-secondary">Item 3</div>
</div>
<div class = "d-flex align-items-end flex-column bg-info mb-3"
style = "height: 200px;">
<div class = "p-2 bg-secondary">Item 1</div>
<div class = "p-2 bg-primary">Item 2</div>
<div class = "mt-auto p-2 bg-warning">mt-auto: Item 3</div>
</div>
</div>
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src = "https://code.jquery.com/jquery-3.2.1.slim.min.js"
integrity = "sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN"
crossorigin = "anonymous">
</script>
<!-- Popper -->
<script src = "https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js"
integrity = "sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q"
crossorigin = "anonymous">
</script>
<!-- Latest compiled and minified Bootstrap JavaScript -->
<script src = "https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"
integrity = "sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl"
crossorigin = "anonymous">
</script>
</body>
</html>Isso produzirá o seguinte resultado -
Resultado
Ordem
O flex usa utilitários de pedido para alterar a ordem dos itens flexíveis em um contêiner, conforme mostrado no exemplo a seguir -
Exemplo
<html>
<head>
<!-- Meta tags -->
<meta charset = "utf-8">
<meta name = "viewport" content = "width = device-width, initial-scale = 1, shrink-to-fit = no">
<!-- Bootstrap CSS -->
<link rel = "stylesheet"
href = "https://maxcdn.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css">
<title>Bootstrap 4 Example</title>
</head>
<body>
<div class = "container">
<h2>Flex Items Order</h2>
<div class = "d-flex flex-nowrap bg-info">
<div class = "order-3 p-2 bg-secondary">'order-3': Item 1</div>
<div class = "order-1 p-2 bg-primary">'order-1': Item 2</div>
<div class = "order-2 p-2 bg-warning">'order-2': Item 3</div>
</div>
</div>
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src = "https://code.jquery.com/jquery-3.2.1.slim.min.js"
integrity = "sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN"
crossorigin = "anonymous">
</script>
<!-- Popper -->
<script src = "https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js"
integrity = "sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q"
crossorigin = "anonymous">
</script>
<!-- Latest compiled and minified Bootstrap JavaScript -->
<script src = "https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"
integrity = "sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl"
crossorigin = "anonymous">
</script>
</body>
</html>Isso produzirá o seguinte resultado -
Resultado
Alinhar Conteúdo
Você pode alinhar (como início, fim, centro, entre e ao redor) os itens flexíveis no eixo cruzado do contêiner usando o utilitário de alinhamento de conteúdo .
O exemplo a seguir demonstra isso -
Exemplo
<html>
<head>
<!-- Meta tags -->
<meta charset="utf-8">
<meta name = "viewport" content = "width = device-width, initial-scale = 1, shrink-to-fit = no">
<!-- Bootstrap CSS -->
<link rel = "stylesheet"
href = "https://maxcdn.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css">
<title>Bootstrap 4 Example</title>
</head>
<body>
<div class = "container">
<h2>align-content-start</h2>
<div class = "d-flex bg-info align-content-start flex-wrap" style = "height: 150px">
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
</div>
<br>
<h2>align-content-end</h2>
<div class = "d-flex bg-info align-content-end flex-wrap" style = "height: 150px">
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
</div>
<br>
<h2>align-content-center</h2>
<div class = "d-flex bg-info align-content-center flex-wrap" style = "height: 150px">
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
</div>
<br>
<h2>align-content-between</h2>
<div class = "d-flex bg-info align-content-between flex-wrap" style = "height: 150px">
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
</div>
<br>
<h2>align-content-around</h2>
<div class = "d-flex bg-info align-content-around flex-wrap" style = "height: 150px">
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
<div class = "p-2 border border-dark">Demo Item</div>
</div>
<br>
</div>
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src = "https://code.jquery.com/jquery-3.2.1.slim.min.js"
integrity = "sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN"
crossorigin = "anonymous">
</script>
<!-- Popper -->
<script src = "https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js"
integrity = "sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q"
crossorigin = "anonymous">
</script>
<!-- Latest compiled and minified Bootstrap JavaScript -->
<script src = "https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"
integrity = "sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl"
crossorigin = "anonymous">
</script>
</body>
</html>Isso produzirá o seguinte resultado -