:root {
  --bg: #0d1117;
  --surface: #161b22;
  --surface-soft: #151a20;
  --accent: #58a6ff;
  --accent-soft: #79b8ff;
  --text: #e6edf3;
  --muted: #8b949e;
  --border: #30363d;
  --danger: #f85149;
}

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

html,
body {
  height: 100%;
  margin: 0;
  font-family: "Segoe UI", Roboto, system-ui, -apple-system, BlinkMacSystemFont,
    "Helvetica Neue", Arial, sans-serif;
  background-color: var(--bg);
  color: var(--text);
}

/* Layout wrappers */

body {
  display: flex;
  flex-direction: column;
}

/* Header & navigation */

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(13, 17, 23, 0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.nav-bar {
  max-width: 960px;
  margin: 0 auto;
  padding: 0.75rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}

.brand {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--text);
  text-decoration: none;
}

.brand::before {
  content: ">";
  margin-right: 0.35rem;
  color: var(--accent);
  font-weight: 700;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.nav-links a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.95rem;
  padding: 0.3rem 0.4rem;
  border-radius: 4px;
  transition: color 0.15s ease, background-color 0.15s ease;
}

.nav-links a:hover {
  color: var(--text);
  background-color: rgba(88, 166, 255, 0.08);
}

.nav-links a.active {
  color: var(--accent);
  background-color: rgba(88, 166, 255, 0.12);
}

/* Main content */

.page-container {
  max-width: 960px;
  width: 100%;
  margin: 0 auto;
  padding: 2rem 1.5rem 3rem;
}

/* Hero section */

.hero {
  background: radial-gradient(circle at top left, #1a2333, #0d1117 60%);
  border-radius: 16px;
  padding: 2rem 1.75rem;
  margin-bottom: 2rem;
  border: 1px solid var(--border);
  box-shadow: 0 18px 40px rgba(0, 0, 0, 0.55);
}

.hero h1 {
  margin: 0 0 0.75rem;
  font-size: clamp(1.9rem, 3vw, 2.3rem);
  letter-spacing: 0.02em;
}

.hero .subtitle {
  margin: 0 0 1.5rem;
  color: var(--muted);
  font-size: 0.98rem;
  max-width: 40rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

/* Buttons */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.7rem 1.2rem;
  border-radius: 999px;
  border: 1px solid transparent;
  font-size: 0.95rem;
  font-weight: 500;
  cursor: pointer;
  text-decoration: none;
  transition: background-color 0.15s ease, border-color 0.15s ease,
    transform 0.05s ease;
}

.btn.primary {
  background-color: var(--accent);
  border-color: var(--accent);
  color: #0b1017;
}

.btn.primary:hover {
  background-color: var(--accent-soft);
  border-color: var(--accent-soft);
  transform: translateY(-1px);
}

.btn.secondary {
  background-color: transparent;
  border-color: var(--border);
  color: var(--text);
}

.btn.secondary:hover {
  border-color: var(--accent);
  background-color: rgba(88, 166, 255, 0.07);
  transform: translateY(-1px);
}




.btn.success {
  background-color: #2ea043;
  border-color: #2ea043;
  color: #0b1017;
}

.btn.success:hover {
  filter: brightness(1.06);
  transform: translateY(-1px);
}

.btn.danger {
  background-color: var(--danger);
  border-color: var(--danger);
  color: #0b1017;
}

.btn.danger:hover {
  filter: brightness(1.06);
  transform: translateY(-1px);
}

.btn:disabled {
  opacity: 0.75;
  cursor: not-allowed;
  transform: none !important;
}




/* Generic sections */

.section {
  background-color: var(--surface);
  border-radius: 12px;
  border: 1px solid var(--border);
  padding: 1.5rem 1.75rem;
  margin-bottom: 1.5rem;
}

.section h2 {
  margin: 0 0 0.75rem;
  font-size: 1.1rem;
}

.section p {
  margin: 0.3rem 0 0;
  color: var(--muted);
  font-size: 0.95rem;
  line-height: 1.6;
}

/* Feature list (what you'll learn) */

.feature-list {
  list-style: none;
  padding: 0;
  margin: 0.75rem 0 0;
  display: grid;
  gap: 0.5rem;
}

.feature-list li {
  position: relative;
  padding-left: 1.25rem;
  color: var(--text);
  font-size: 0.95rem;
}

.feature-list li::before {
  content: "▹";
  position: absolute;
  left: 0;
  top: 0.15rem;
  color: var(--accent);
}

/* Utility text */

.muted {
  color: var(--muted);
}

/* Basic responsive adjustments */

@media (max-width: 720px) {
  .nav-bar {
    padding-inline: 1rem;
  }

  .nav-links {
    gap: 0.6rem;
  }

  .page-container {
    padding-inline: 1rem;
  }

  .hero {
    padding: 1.6rem 1.3rem;
  }

  .hero-actions {
    flex-direction: column;
    align-items: flex-start;
  }

  .btn {
    width: 100%;
    justify-content: center;
  }
}

/* Optional: style for future form pages (login, register, etc.) */

.form-card {
  max-width: 420px;
  margin: 2rem auto;
  padding: 1.7rem 1.6rem;
  background-color: var(--surface);
  border-radius: 12px;
  border: 1px solid var(--border);
}

.form-card h1 {
  margin-top: 0;
  margin-bottom: 0.75rem;
  font-size: 1.2rem;
}

.form-card label {
  display: block;
  font-size: 0.85rem;
  margin-top: 0.9rem;
  margin-bottom: 0.35rem;
  color: var(--muted);
}

.form-card input {
  width: 100%;
  padding: 0.55rem 0.65rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  background-color: var(--surface-soft);
  color: var(--text);
  font-size: 0.95rem;
}

.form-card input:focus {
  outline: none;
  border-color: var(--accent);
}

.form-card button {
  margin-top: 1.1rem;
  width: 100%;
}

.form-help {
  margin-top: 0.75rem;
  font-size: 0.85rem;
  color: var(--muted);
}








/* below  is appended after i made courses.html  */
.course-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
}

.course-card {
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.2rem 1.25rem;
}

.course-card h3 {
  margin: 0 0 0.4rem;
  font-size: 1.05rem;
}

.course-card p {
  margin: 0 0 0.9rem;
  color: var(--muted);
  line-height: 1.6;
  font-size: 0.95rem;
}

.course-card .card-actions {
  display: flex;
  gap: 0.6rem;
  flex-wrap: wrap;
}

@media (max-width: 720px) {
  .course-grid {
    grid-template-columns: 1fr;
  }
}



/* Markdown lesson styling */
.markdown {
  margin-top: 1rem;
  line-height: 1.75;
}

.markdown h1, .markdown h2, .markdown h3 {
  margin-top: 1.2rem;
  margin-bottom: 0.6rem;
}

.markdown p {
  color: var(--text);
}

.markdown code {
  padding: 0.15rem 0.35rem;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--surface-soft);
}

.markdown pre {
  padding: 1rem;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--surface-soft);
  overflow-x: auto;
}

.markdown pre code {
  border: none;
  padding: 0;
  background: transparent;
}




/* Course outline */
.outline-module {
  margin-top: 1rem;
  padding: 1rem;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface);
}

.outline-module h3 {
  margin: 0 0 0.75rem;
  font-size: 1.05rem;
}

.outline-lessons {
  margin: 0;
  padding-left: 1.2rem;
}

.outline-lessons li {
  margin: 0.5rem 0;
  display: flex;
  gap: 0.75rem;
  align-items: center;
}

.badge {
  font-size: 0.8rem;
  padding: 0.15rem 0.55rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--muted);
}

.badge.locked {
  opacity: 0.7;
}




.lesson-outline a.current {
  font-weight: 600;
  text-decoration: underline;
}

.lesson-outline .lesson-row {
  display: flex;
  gap: 0.75rem;
  align-items: center;
  margin: 0.45rem 0;
}



/* Lesson outline link styling (make current lesson obvious) */
.lesson-outline a {
  color: var(--muted);
  text-decoration: none; /* remove default underline so "current" stands out */
  display: inline-block;
  padding: 0.35rem 0.5rem;
  border-radius: 10px;
  border: 1px solid transparent;
}

.lesson-outline a:hover {
  color: var(--text);
  background: rgba(88, 166, 255, 0.07);
  border-color: rgba(88, 166, 255, 0.18);
}

.lesson-outline a.current {
  color: var(--text);
  font-weight: 600;
  background: rgba(88, 166, 255, 0.16);
  border-color: rgba(88, 166, 255, 0.45);
  box-shadow: 0 0 0 2px rgba(88, 166, 255, 0.12) inset;
}







/* Lesson outline link styling (make current lesson obvious) */
.lesson-outline a {
  color: var(--muted);
  text-decoration: none; /* remove default underline so "current" stands out */
  display: inline-block;
  padding: 0.35rem 0.5rem;
  border-radius: 10px;
  border: 1px solid transparent;
}

.lesson-outline a:hover {
  color: var(--text);
  background: rgba(88, 166, 255, 0.07);
  border-color: rgba(88, 166, 255, 0.18);
}

.lesson-outline a.current {
  color: var(--text);
  font-weight: 600;
  background: rgba(88, 166, 255, 0.16);
  border-color: rgba(88, 166, 255, 0.45);
  box-shadow: 0 0 0 2px rgba(88, 166, 255, 0.12) inset;
}




/* Auth forms */
.auth-form {
  display: grid;
  gap: 0.85rem;
}

.auth-label {
  display: grid;
  gap: 0.4rem;
  color: var(--text);
  font-size: 0.95rem;
}

.auth-input {
  padding: 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--surface-soft);
  color: var(--text);
  outline: none;
}

.auth-input:focus {
  border-color: var(--accent);
}