:root {
    --header-height: 60px;
}

*, *::before, *::after {
  box-sizing: border-box;
}

body {
  font-family: Arial, sans-serif;
  background: #f5f5f5;
  margin: 0;
  padding: 0;

  padding-top: var(--header-height);
}

.error {
    color: #c00;
    margin-top: 1rem;
    display: none;
}

.hidden {
  display: none;
}

.border_test {
    border: 1px solid red;
}