<?php
$erro = isset($_GET['erro']) ? "Login ou senha inválidos." : "";
?>
<!DOCTYPE html>
<html lang="pt-br">
<head>
  <meta charset="UTF-8">
  <title>Login</title>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
  <style>
    body {
      background-color: #f5f5f5;
    }
    .login-container {
      margin-top: 100px;
    }
    .login-box {
      max-width: 400px;
      padding: 30px;
      background: #fff;
      border-radius: 8px;
      box-shadow: 0 0 10px rgba(0,0,0,0.2);
      margin: 0 auto;
    }
    .login-box h3 {
      margin-bottom: 20px;
      text-align: center;
    }
  </style>
</head>
<body>
<div class="container login-container">
  <div class="login-box">
    <center><img src="https://colegioavila.com.br/wp-content/uploads/2019/02/logo-chanfrado01.png" width="200px"></center>
    <?php if (!empty($erro)): ?>
      <div class="alert alert-danger"><?= $erro ?></div>
      
    <?php endif; ?>
    <form method="POST" action="validarLogin.php">
      <div class="form-group">
        <label for="login">Usuário</label>
        <input type="text" name="login" class="form-control" id="login" required autofocus>
      </div>
      <div class="form-group">
        <label for="senha">Senha</label>
        <input type="password" name="senha" class="form-control" id="senha" required>
      </div>
      <button type="submit" class="btn btn-success btn-block">Entrar</button>
    </form>
  </div>
</div>
</body>
</html>
