body {
  background: #181826;
  color: #fff;
  font-family: 'Arial Black', Arial, sans-serif;
  line-height: 1.8;
}
#container {
  max-width: 890px;
  margin: 30px auto;
  background: #28293d;
  border-radius: 15px;
  padding: 30px 20px;
  box-shadow: 0 2px 18px 8px rgba(63,63,63,0.18);
}
h1, h2, h3, h4, h5, h6, ul, li, td, th, tr, p, button, pre, code, b {
  font-weight: bold !important;
}
h1, h2 {
  color: #00ffb9;
  text-shadow: 1px 1px 3px #000;
}
ul {
  margin-left: 22px;
}
li {
  margin: 10px 0;
}
table {
  width: 100%;
  background: #151520;
  border-collapse: collapse;
  margin-top: 16px;
}
th, td {
  border: 1.7px solid #00ffb9;
  padding: 14px;
  color: #fff;
  font-weight: bold;
  text-align: center;
}
th {
  background: #0e3460;
  color: #00ffb9;
}
.print-btn {
  position: fixed;
  right: 40px;
  top: 20px;
  font-size: 18px;
  padding: 9px 25px;
  background: #17c0eb;
  color: #121233;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  box-shadow: 0 0 10px #09f2ffb2;
  z-index: 2000;
}
#print-btn:hover { background: #1aceff; }
button {
  background: #27ae60;
  color: #fff;
  border: none;
  border-radius: 7px;
  margin: 6px 2px;
  padding: 9px 20px;
  font-size: 15px;
  cursor: pointer;
  transition: background .2s;
  box-shadow: 0 2px 10px 1px #0ef0c433;
}
button:hover {
  background: #00b894;
  color: #fff;
}
#nav ul {
  list-style: none;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 22px;
}
#nav ul li {
  margin: 0;
}
.qa {
  margin-bottom: 28px;
}
.answer {
  display: none;
  background: #353661;
  color: #fff !important;
  border-radius: 11px;
  padding: 13px 28px;
  margin-top: 12px;
  font-size: 1em;
}
pre, code {
  background: #112030;
  color: #00ffe7;
  font-weight: bold;
  font-size: 1.1em;
  font-family: 'Courier New', monospace;
  border-radius: 7px;
  padding: 6px 12px;
  display: block;
}
@media print {
  .print-btn, #nav { display: none !important; }
  #container { background: #fff; color: #181826; }
  h1, h2, th { color: #0e3460 !important; }
}