:root {
  --gradient-start: #4f46e5; /* indigo-600 */
  --gradient-end: #0ea5e9;   /* sky-500 */
  --color-bg: #f7f8fc;
  --color-surface: #ffffff;
  --color-text: #1f2933;
  --color-muted: #64748b;
  --color-accent: #2563eb;
  --color-accent-strong: #1d4ed8;
  --card-shadow: rgba(15, 23, 42, 0.08);
  --nav-bg: rgba(255, 255, 255, 0.92);
  --nav-shadow: rgba(15, 23, 42, 0.08);
  --hero-text: #f8fafc;
  --social-bg: rgba(255, 255, 255, 0.18);
  --social-hover: rgba(255, 255, 255, 0.32);
  --bs-body-bg: var(--color-bg);
  --bs-body-color: var(--color-text);
  --brand-highlight-start: #f97316;
  --brand-highlight-end: #facc15;
}

[data-theme="dark"] {
  --gradient-start: #1e293b;
  --gradient-end: #0f172a;
  --color-bg: #0b1120;
  --color-surface: #111c2f;
  --color-text: #e2e8f0;
  --color-muted: #94a3b8;
  --color-accent: #60a5fa;
  --color-accent-strong: #3b82f6;
  --card-shadow: rgba(2, 6, 23, 0.65);
  --nav-bg: rgba(11, 18, 32, 0.92);
  --nav-shadow: rgba(2, 6, 23, 0.65);
  --hero-text: #e2e8f0;
  --social-bg: rgba(148, 163, 184, 0.18);
  --social-hover: rgba(148, 163, 184, 0.32);
  --bs-body-bg: var(--color-bg);
  --bs-body-color: var(--color-text);
  --brand-highlight-start: #fbbf24;
  --brand-highlight-end: #f97316;
}

html,
body {
  background-color: var(--color-bg);
  color: var(--color-text);
  font-family: "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.7;
}

body,
.navbar,
.navbar .nav-link,
.hero,
.section-card,
.content-card,
.theme-toggle,
footer {
  transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}

a {
  color: var(--color-accent-strong);
}

a:hover {
  color: var(--color-accent);
}

.navbar {
  background-color: var(--nav-bg);
  box-shadow: 0 2px 10px var(--nav-shadow);
  backdrop-filter: blur(8px);
  border-radius: 1rem;
  margin: 1.5rem auto;
  padding: 0.75rem 1.5rem;
}

.navbar-brand,
.navbar .nav-link {
  color: var(--color-text) !important;
  font-weight: 500;
}

.navbar-brand .brand-emphasis {
  position: relative;
  display: inline-block;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--brand-highlight-end);
  text-transform: uppercase;
}

@supports (-webkit-background-clip: text) or (background-clip: text) {
  .navbar-brand .brand-emphasis {
    background: linear-gradient(135deg, var(--brand-highlight-start), var(--brand-highlight-end));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
  }
}

.navbar .nav-link:hover,
.navbar .nav-link:focus {
  color: var(--color-accent) !important;
}

.navbar-toggler {
  border: none;
}

.navbar-toggler:focus {
  box-shadow: 0 0 0 0.15rem rgba(59, 130, 246, 0.25);
}

.theme-toggle {
  border-color: rgba(148, 163, 184, 0.45);
  color: var(--color-text);
  background-color: transparent;
}

.theme-toggle:hover {
  background-color: rgba(148, 163, 184, 0.12);
  color: var(--color-accent-strong);
}

.btn-hero {
  border: none;
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  color: #f8fafc;
  padding: 0.8rem 1.9rem;
  border-radius: 999px;
  font-weight: 600;
  box-shadow: 0 18px 30px rgba(79, 70, 229, 0.35);
  transition: transform 0.2s ease, box-shadow 0.2s ease, opacity 0.2s ease;
}

.btn-hero:hover,
.btn-hero:focus {
  color: #f8fafc;
  transform: translateY(-2px);
  box-shadow: 0 22px 36px rgba(79, 70, 229, 0.4);
  opacity: 0.96;
}

.btn-hero:active {
  transform: translateY(0);
  box-shadow: 0 12px 24px rgba(79, 70, 229, 0.25);
}

.icon-badge {
  width: 60px;
  height: 60px;
  border-radius: 18px;
  background-color: rgba(37, 99, 235, 0.12);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 1rem auto;
  color: var(--color-accent);
  box-shadow: 0 10px 24px rgba(37, 99, 235, 0.18);
}

[data-theme="dark"] .icon-badge {
  background-color: rgba(96, 165, 250, 0.16);
  box-shadow: 0 12px 28px rgba(15, 23, 42, 0.55);
  color: var(--color-accent);
}

.icon-badge .bi {
  font-size: 1.75rem;
}

.feature-icon {
  width: 40px;
  height: 40px;
  display: block;
  color: currentColor;
}

.hero {
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  border-radius: 1.5rem;
  color: var(--hero-text);
  box-shadow: 0 20px 40px rgba(79, 70, 229, 0.35);
  margin-bottom: 3rem;
  padding: clamp(2.5rem, 5vw, 4rem);
}

.hero .section-heading {
  color: rgba(248, 250, 252, 0.7);
}

.section-heading {
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-size: 0.85rem;
  color: var(--color-muted);
}

.section-card {
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 1rem;
  box-shadow: 0 15px 35px var(--card-shadow);
  background-color: var(--color-surface);
}

.section-card h2,
.section-card h3 {
  color: var(--color-text);
}

.section-card p.small,
.section-card p.small.text-muted,
.section-card p.text-muted {
  color: var(--color-muted) !important;
}

.social-links a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--social-bg);
  color: var(--hero-text);
  margin-right: 0.75rem;
  transition: transform 0.2s ease, background-color 0.2s ease;
}

.social-links a:hover {
  transform: translateY(-3px);
  background: var(--social-hover);
}

.content-card {
  border-radius: 1.25rem;
  background-color: var(--color-surface);
  padding: clamp(2rem, 5vw, 3rem);
  box-shadow: 0 12px 30px var(--card-shadow);
}

footer {
  font-size: 0.9rem;
  color: var(--color-muted);
}

.markdown-body {
  color: var(--color-text);
  font-size: 1rem;
  line-height: 1.8;
}

.markdown-body h1,
.markdown-body h2,
.markdown-body h3,
.markdown-body h4 {
  font-weight: 600;
  margin-top: 2.5rem;
  margin-bottom: 1rem;
  color: var(--color-text);
}

.markdown-body h1:first-child,
.markdown-body h2:first-child,
.markdown-body h3:first-child,
.markdown-body h4:first-child {
  margin-top: 0;
}

.markdown-body p {
  margin-bottom: 1.25rem;
}

.markdown-body ul,
.markdown-body ol {
  margin-bottom: 1.5rem;
  padding-left: 1.25rem;
}

.markdown-body blockquote {
  border-left: 4px solid var(--color-accent);
  padding-left: 1rem;
  color: var(--color-muted);
  font-style: italic;
}

.markdown-body code {
  background-color: rgba(148, 163, 184, 0.15);
  padding: 0.15rem 0.35rem;
  border-radius: 0.35rem;
  font-size: 0.95em;
}

.markdown-body pre {
  background-color: rgba(15, 23, 42, 0.85);
  color: #e2e8f0;
  padding: 1rem 1.25rem;
  border-radius: 0.75rem;
  overflow-x: auto;
}

.markdown-body pre code {
  background: none;
  color: inherit;
  padding: 0;
}

@media (max-width: 991.98px) {
  .navbar {
    border-radius: 1rem;
    margin: 1rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    transition: none !important;
  }
}