.box-main {
  background-color: #f9f9f9;
  border-radius: 5px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  padding: 20px;
  margin: 20px auto;
  max-width: 600px;
}


label {
  display: block;
  margin-bottom: 5px;
  font-weight: bold;
  color: #333;
}

input[type="text"],
input[type="email"],
textarea {
  width: 100%;
  padding: 10px;
  margin-bottom: 15px;
  border: 1px solid #ccc;
  border-radius: 4px;
}

textarea {
  resize: vertical;
}

input[type="checkbox"] {
  margin-right: 5px;
}


input[type="submit"] {
  background-color: #333;
  color: white;
  border: none;
  padding: 10px 20px;
  border-radius: 4px;
  cursor: pointer;
}

input[type="submit"]:hover {
  background-color: #555;
}


input:invalid,
textarea:invalid {
  border-color: #e74c3c;
}

input:invalid::placeholder,
textarea:invalid::placeholder {
  color: #e74c3c;
}


input:required,
textarea:required {
  background-color: #ffffff;
}


@media screen and (max-width: 768px) {
  .box-main {
      margin: 20px;
  }
}