:root {
  --brand-main: #6366f1;
  --brand-light: #e0e7ff;
  --bg-main: #f4f6f9;
  --container-bg: #ffffff;
  --text-primary: #334155;
  --text-muted: #64748b;
  --border-color: #cbd5e1;
  --code-bg: #1e293b;
  --code-text: #f8fafc;
}

body {
  font-family: "Nunito", sans-serif;
  background-color: var(--bg-main);
  color: var(--text-primary);
  line-height: 1.6;
  margin: 0;
  padding: 40px 20px;
}

.lesson-container {
  max-width: 900px;
  margin: 0 auto;
  background: var(--container-bg);
  border-radius: 16px;
  padding: 40px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.05);
  border: 2px solid var(--border-color);
}

h1 {
  color: var(--brand-main);
  font-size: 2.5rem;
  font-weight: 800;
  margin-top: 0;
  border-bottom: 3px solid var(--brand-light);
  padding-bottom: 15px;
}

h2 {
  color: var(--text-primary);
  font-size: 1.5rem;
  font-weight: 700;
  margin-top: 35px;
  margin-bottom: 15px;
  display: flex;
  align-items: center;
  gap: 10px;
}

h2 i {
  color: var(--brand-main);
}

h3 {
  color: var(--text-primary);
  font-size: 1.2rem;
  margin-top: 25px;
  margin-bottom: 10px;
}

p,
ul {
  font-size: 1.05rem;
  color: var(--text-primary);
}

li {
  margin-bottom: 8px;
}

.highlight-box {
  background-color: var(--brand-light);
  border-left: 5px solid var(--brand-main);
  padding: 20px;
  border-radius: 0 12px 12px 0;
  margin: 25px 0;
}

.highlight-box strong {
  color: var(--brand-main);
}

.warning-box {
  background-color: #fee2e2;
  border-left: 5px solid #ef4444;
  padding: 20px;
  border-radius: 0 12px 12px 0;
  margin: 25px 0;
}

.warning-box strong {
  color: #ef4444;
}

pre {
  background-color: var(--code-bg);
  color: var(--code-text);
  padding: 15px;
  border-radius: 8px;
  overflow-x: auto;
  font-family: "Consolas", monospace;
  font-size: 0.95rem;
}

code.inline {
  background-color: #e2e8f0;
  color: #b91c1c;
  padding: 2px 6px;
  border-radius: 4px;
  font-family: "Consolas", monospace;
  font-size: 0.9rem;
}

.complexity-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 20px;
}

.complexity-table th,
.complexity-table td {
  text-align: left;
  padding: 15px;
  border-bottom: 1px solid var(--border-color);
}

.complexity-table th {
  background-color: var(--bg-main);
  font-weight: 800;
}