/* ===== DESIGN TOKENS ===== */
:root {
  --bg-primary: #080c14;
  --bg-secondary: #0e1420;
  --bg-card: #111827;
  --bg-card-hover: #162032;
  --bg-glass: rgba(14, 20, 32, 0.7);

  --accent-blue: #3b82f6;
  --accent-cyan: #06b6d4;
  --accent-purple: #8b5cf6;
  --accent-pink: #ec4899;
  --accent-green: #10b981;
  --accent-orange: #f59e0b;

  --lpf-color: #06b6d4;
  --lpf-glow: rgba(6, 182, 212, 0.3);
  --hpf-color: #8b5cf6;
  --hpf-glow: rgba(139, 92, 246, 0.3);

  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #4b5563;

  --border-color: rgba(255, 255, 255, 0.06);
  --border-glow: rgba(59, 130, 246, 0.3);

  --code-bg: #0d1117;
  --code-text: #e2e8f0;
  --code-accent: #38bdf8;

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-xl: 28px;

  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 8px 32px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 24px 64px rgba(0, 0, 0, 0.6);
  --shadow-glow-blue: 0 0 40px rgba(59, 130, 246, 0.2);
  --shadow-glow-cyan: 0 0 40px rgba(6, 182, 212, 0.2);
  --shadow-glow-purple: 0 0 40px rgba(139, 92, 246, 0.2);

  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 450ms cubic-bezier(0.4, 0, 0.2, 1);

  --font-body: 'Inter', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
}

[data-theme="light"] {
  --bg-primary: #f8fafc;
  --bg-secondary: #f1f5f9;
  --bg-card: #ffffff;
  --bg-card-hover: #f1f5f9;
  --bg-glass: rgba(255, 255, 255, 0.9);

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;

  --border-color: rgba(0, 0, 0, 0.08);
  --border-glow: rgba(59, 130, 246, 0.1);

  --code-bg: #f1f5f9;
  --code-text: #0f172a;
  --code-accent: #2563eb;
}

/* ===== RESET & BASE ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-body);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

::selection {
  background: rgba(59, 130, 246, 0.4);
  color: #fff;
}

a {
  text-decoration: none;
  color: inherit;
}

img, canvas {
  max-width: 100%;
}

ul { list-style: none; }

/* ===== SCROLLBAR ===== */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--bg-primary); }
::-webkit-scrollbar-thumb { background: #2d3748; border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--accent-blue); }

/* ===== NAVBAR ===== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 0 2rem;
  height: 64px;
  display: flex;
  align-items: center;
  background: var(--bg-glass);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-color);
  transition: all var(--transition-base);
}

.navbar.scrolled {
  background: var(--bg-primary);
  box-shadow: var(--shadow-sm);
  height: 56px;
}


.nav-container {
  max-width: 1280px;
  width: 100%;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--text-primary);
  transition: color var(--transition-fast);
}

.nav-logo:hover { color: var(--accent-blue); }

.logo-icon {
  font-size: 1.25rem;
  filter: drop-shadow(0 0 8px rgba(59,130,246,0.8));
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  margin-left: auto;
}

.nav-link {
  padding: 0.5rem 1rem;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
  position: relative;
}

.nav-link:hover { color: var(--text-primary); background: rgba(255,255,255,0.06); }
.nav-link.active { color: var(--accent-blue); background: rgba(59,130,246,0.1); }

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  margin-left: auto;
}
.nav-toggle span {
  display: block;
  height: 2px;
  width: 22px;
  background: var(--text-secondary);
  border-radius: 1px;
  transition: all var(--transition-base);
}

/* ===== BUTTONS ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.75rem;
  border-radius: var(--radius-md);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: all var(--transition-base);
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent-blue), var(--accent-cyan));
  color: #fff;
  box-shadow: 0 4px 20px rgba(59, 130, 246, 0.4);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(59, 130, 246, 0.6);
}

.btn-secondary {
  background: rgba(255,255,255,0.06);
  color: var(--text-primary);
  border: 1px solid rgba(255,255,255,0.1);
}

.btn-secondary:hover {
  background: rgba(255,255,255,0.12);
  transform: translateY(-2px);
}

.btn-sm {
  padding: 0.5rem 1.25rem;
  font-size: 0.875rem;
}

.btn-lg {
  padding: 1rem 2.5rem;
  font-size: 1.05rem;
}

/* ===== CONTAINER ===== */
.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 2rem;
}

/* ===== SECTION HEADERS ===== */
.section-header { text-align: center; margin-bottom: 3.5rem; }

.section-tag {
  display: inline-block;
  padding: 0.4rem 1rem;
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: rgba(59,130,246,0.12);
  color: var(--accent-blue);
  border: 1px solid rgba(59,130,246,0.2);
  margin-bottom: 1rem;
}

.section-title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 1rem;
}

.section-subtitle {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* ===== GRADIENT TEXT ===== */
.gradient-text {
  background: linear-gradient(135deg, var(--accent-blue), var(--accent-cyan), var(--accent-purple));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  background-size: 200% 200%;
  animation: gradientShift 4s ease infinite;
}

@keyframes gradientShift {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

/* ===== CARDS ===== */
.glass-card {
  background: var(--bg-glass);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2rem;
}

/* ===== PAGE TITLE ===== */
.page-title-section {
  padding: 120px 2rem 60px;
  text-align: center;
  background: radial-gradient(ellipse at 50% 0%, rgba(59,130,246,0.12) 0%, transparent 70%);
}

.page-title-section h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 800;
  margin-bottom: 1rem;
}

.page-title-section p {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 640px;
  margin: 0 auto;
}

/* ===== FOOTER ===== */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 3rem 0 1.5rem;
  margin-top: auto;
}

.footer-content {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 3rem;
  margin-bottom: 2.5rem;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.footer-name {
  font-size: 1.1rem;
  font-weight: 700;
  margin-left: 0.5rem;
}

.footer-brand p {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-top: 0.5rem;
}

.footer-links h4 {
  font-size: 0.875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

.footer-links ul {
  display: flex;
  flex-direction: column;
  gap: 0.625rem;
}

.footer-links a {
  color: var(--text-muted);
  font-size: 0.9rem;
  transition: color var(--transition-fast);
}

.footer-links a:hover { color: var(--accent-blue); }

.footer-bottom {
  border-top: 1px solid var(--border-color);
  padding-top: 1.5rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* ===== CODE BLOCKS ===== */
pre {
  background: var(--code-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: var(--code-text);
}

code.formula {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  background: rgba(59,130,246,0.1);
  border: 1px solid rgba(59,130,246,0.2);
  border-radius: 6px;
  padding: 0.3rem 0.75rem;
  color: var(--accent-cyan);
  display: inline-block;
  margin-top: 0.4rem;
}

/* ===== ANIMATIONS ===== */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(30px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInLeft {
  from { opacity: 0; transform: translateX(-30px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes fadeInRight {
  from { opacity: 0; transform: translateX(30px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}

@keyframes glow {
  0%, 100% { box-shadow: 0 0 20px rgba(59,130,246,0.3); }
  50% { box-shadow: 0 0 40px rgba(59,130,246,0.6); }
}

.animate-in {
  animation: fadeInUp 0.7s cubic-bezier(0.4, 0, 0.2, 1) both;
}

/* ===== TABS ===== */
.tab-nav {
  display: flex;
  gap: 0.5rem;
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  padding: 0.375rem;
  border: 1px solid var(--border-color);
  margin-bottom: 2rem;
}

.tab-btn {
  flex: 1;
  padding: 0.75rem 1.25rem;
  border: none;
  border-radius: var(--radius-md);
  background: transparent;
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-base);
  font-family: var(--font-body);
}

.tab-btn:hover { color: var(--text-primary); background: rgba(255,255,255,0.05); }
.tab-btn.active {
  background: linear-gradient(135deg, var(--accent-blue), var(--accent-cyan));
  color: #fff;
  box-shadow: 0 4px 12px rgba(59,130,246,0.4);
}

.tab-panel { display: none; }
.tab-panel.active { display: block; }

/* ===== SLIDER ===== */
.slider-container {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.slider-label {
  font-size: 0.875rem;
  color: var(--text-secondary);
  min-width: 100px;
}

.slider-value {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--accent-cyan);
  font-weight: 600;
  min-width: 60px;
  text-align: right;
}

input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  background: rgba(255,255,255,0.1);
  border-radius: 3px;
  outline: none;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent-blue), var(--accent-cyan));
  cursor: pointer;
  box-shadow: 0 0 10px rgba(59,130,246,0.5);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.2);
  box-shadow: 0 0 16px rgba(59,130,246,0.8);
}

input[type="range"]::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent-blue), var(--accent-cyan));
  cursor: pointer;
  border: none;
  box-shadow: 0 0 10px rgba(59,130,246,0.5);
}

/* ===== SELECT ===== */
select {
  background: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 0.5rem 1rem;
  font-family: var(--font-body);
  font-size: 0.875rem;
  cursor: pointer;
  outline: none;
  transition: border-color var(--transition-fast);
}

select:focus { border-color: var(--accent-blue); }

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  .nav-links { display: none; }
  .nav-toggle { display: flex; }

  .footer-content {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .tab-nav { flex-direction: column; }
}

@media (max-width: 480px) {
  .container { padding: 0 1rem; }
  .btn { padding: 0.65rem 1.25rem; font-size: 0.875rem; }
}