* {
  box-sizing: border-box;
}

body {
  font-family: Arial, Helvetica, sans-serif;
  margin: 0;
  min-height: 100vh;

  display: flex;
  align-items: center;
  justify-content: center;

  background: #f4f5f7;
  color: #333;
}

main {
  width: 100%;
  max-width: 620px;

  margin: 30px;
  padding: 40px;

  background: white;

  border-radius: 10px;

  box-shadow:
    0 4px 18px rgba(0, 0, 0, 0.08);
}

h1 {
  margin-top: 0;
  margin-bottom: 20px;
}

#status {
  margin-bottom: 25px;
}

.acoes {
  display: flex;
  flex-direction: column;
  gap: 12px;

  margin-bottom: 20px;
}

.botao,
button {
  display: block;

  width: 100%;

  padding: 12px 16px;

  border: 0;
  border-radius: 5px;

  font-size: 16px;
  text-align: center;

  cursor: pointer;
}

.botao {
  text-decoration: none;

  background: #3472f7;
  color: white;
}

.botao:hover {
  opacity: 0.9;
}

.dashboard {
  background: #23ccef;
}

button {
  background: #fb404b;
  color: white;
}


/* Interface da atividade Desenho Assinado */
.cartao {
  margin: 1.5rem 0;
  padding: 1.25rem;
  border: 1px solid #30363d;
  border-radius: 12px;
  background: rgba(22, 27, 34, 0.72);
}
.cartao h2 { margin-top: 0; }
#formulario { display: grid; gap: .75rem; max-width: 28rem; }
#numero { width: 100%; box-sizing: border-box; padding: .7rem; }
button:disabled { opacity: .55; cursor: not-allowed; }
#desenho { margin: 1.5rem auto; max-width: 800px; }
#desenho img { display: block; width: 100%; height: auto; }
#mensagem { color: #ff8a8a; }