:root {
  --bg: #1e1e1e;
  --fg: #f2f2f2;
  --accent: #f9a826;
  --font: "Segoe UI", sans-serif;
}
body {
  background-color: var(--bg);
  color: var(--fg);
  font-family: var(--font);
  margin: 0;
  padding: 0;
  line-height: 1.6;
}
.site-header {
  text-align: center;
  padding: 1.5em;
  background-color: var(--bg);
  color: var(--accent);
  border-bottom: 1px solid var(--accent);
}
main {
  padding: 2em;
  max-width: 700px;
  margin: 0 auto;
}
form input, form textarea {
  width: 100%;
  padding: 0.75em;
  margin-bottom: 1em;
  border: none;
  border-radius: 4px;
  background: #333;
  color: var(--fg);
}
form button {
  width: 100%;
  padding: 0.75em;
  background: var(--accent);
  border: none;
  border-radius: 4px;
  color: #000;
  font-weight: bold;
  cursor: pointer;
}
form button:hover {
  background: #ffd47f;
}
ul#invoice-list {
  list-style: none;
  padding: 0;
  padding-bottom: 150px;
}
ul#invoice-list li {
  background: #292929;
  padding: 1em;
  margin-bottom: 0.75em;
  border-left: 4px solid var(--accent);
  border-radius: 4px;
}
aside#invoice-sidebar {
  display: none;
}
@media (min-width: 769px) {
  aside#invoice-sidebar {
    display: block;
    position: fixed;
    left: 0;
    top: 0;
    height: 100%;
    width: 250px;
    background: var(--bg);
    color: var(--fg);
    padding: 1em;
    overflow-y: auto;
    z-index: 1000;
  }
  main {
    margin-left: 260px;
  }
}
@media print {
  body, header, footer, main {
    background: #fff;
    color: #000;
  }
  form, button, header, footer, aside {
    display: none;
  }
  ul#invoice-list li {
    border: none;
    background: none;
    padding: 0;
  }
}