* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  font-family: "Segoe UI", Arial, sans-serif;
  background: #050607;
  color: #23272f;
  margin: 0;
  padding: 0;
}
.container-main {
  max-width: 1100px;
  margin: 40px auto;
  background: #2f4774;
  box-shadow: 0 4px 32px rgba(30, 64, 175, 0.09);
  border-radius: 16px;
  padding: 40px 18px 38px 18px;
}
h1 {
  color: #db6c12;
  font-size: 2.7rem;
  margin-bottom: 12px;
  text-align: center;
  letter-spacing: 1px;
}
.section-index {
  background: #0369a1;
  border-radius: 12px;
  padding: 18px 20px;
  margin-bottom: 35px;
  box-shadow: 0 2px 8px rgba(96, 165, 250, 0.06);
}
.section-index ul {
  columns: 2;
  padding-left: 0;
  list-style: none;
  margin: 0;
}
.section-index li {
  margin-bottom: 8px;
  font-size: 1.09em;
  font-weight: 500;
}
a {
  color: #ffffff;
  text-decoration: none;
  transition: color 0.2s;
}
a:hover {
  color: #0e3a7d;
  text-decoration: underline;
}
.topic-box {
  background: #64728f;
  color: #010047;
  font-weight: 500;
  border-radius: 13px;
  margin-bottom: 28px;
  padding: 28px 22px 18px 22px;
  box-shadow: 0 2px 12px rgba(59, 130, 246, 0.04);
  position: relative;
  border-left: 7px solid #2563eb;
}
.topic-title {
  margin: 0 0 13px 0;
  font-size: 1.25rem;
  color: #1e293b;
  font-weight: bold;
  letter-spacing: 1px;
  display: flex;
  align-items: center;
}
.topic-index {
  background: #2563eb;
  color: #fff;
  border-radius: 7px;
  font-size: 1.04em;
  padding: 3px 13px;
  margin-right: 14px;
  font-weight: bold;
  letter-spacing: 1px;
  box-shadow: 0 1px 7px rgba(37, 99, 235, 0.1);
}
.btn-top {
  position: absolute;
  right: 22px;
  top: 24px;
  border: none;
  background: #2563eb;
  color: #fff;
  border-radius: 5px;
  padding: 4px 13px;
  cursor: pointer;
  font-size: 1em;
  transition: background 0.18s;
  box-shadow: 0 1px 7px rgba(37, 99, 235, 0.11);
}
.btn-top:hover {
  background: #1e293b;
  color: #fff;
}
pre {
  background: #e0e7ef;
  padding: 16px 20px;
  border-radius: 7px;
  overflow-x: auto;
  font-size: 1.05em;
  margin: 14px 0 10px 0;
  border-left: 4px solid #60a5fa;
  font-family: "Fira Mono", "Consolas", monospace;
}
.output {
  background: #dcfce7;
  color: #166534;
  padding: 9px 15px;
  border-radius: 6px;
  margin: 3px 0 15px 0;
  border-left: 4px solid #16a34a;
  font-family: "Fira Mono", monospace;
  font-size: 1.01em;
}
.note {
  color: #f59e42;
  background: #fff7ed;
  border-left: 5px solid #f59e42;
  padding: 12px 17px;
  margin: 16px 0 11px 0;
  border-radius: 8px;
  font-size: 1em;
}
.tip {
  background: #e0f2fe;
  color: #0369a1;
  border-left: 4px solid #0ea5e9;
  padding: 12px 18px;
  margin: 16px 0 16px 0;
  border-radius: 8px;
}
ul,
ol {
  margin-left: 1.3em;
  margin-bottom: 0.6em;
}
table {
  border-collapse: collapse;
  margin: 10px 0 18px 0;
  background: #f1f5f9;
  border-radius: 8px;
  overflow: hidden;
  width: 100%;
}
th,
td {
  border: 1px solid #e0e7ef;
  padding: 8px 12px;
  text-align: left;
  font-size: 1em;
}
th {
  background: #2563eb;
  color: #fff;
}

#bottom {
    color: #16a34a;
    font-weight: 700;
    display: flex;
    justify-content: center;
    align-items: center;
}
@media (max-width: 700px) {
  .container-main {
    padding: 7px;
  }
  .section-index ul {
    columns: 1;
  }
  .btn-top {
    top: 13px;
    right: 10px;
  }
  table,
  th,
  td {
    font-size: 0.97em;
  }
}