@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@400;500;600;700;800&family=Inter:wght@400;500;600;700&display=swap');

:root {
  /* Brand Core */
  --brand-blue: #0838A0;
  --brand-blue-hover: #062b7c;
  --brand-blue-light: #2563EB;
  --brand-blue-subtle: rgba(8, 56, 160, 0.08);
  --brand-blue-glow: rgba(8, 56, 160, 0.22);
  
  --brand-orange: #F09018;
  --brand-orange-hover: #d97d0e;
  --brand-orange-subtle: rgba(240, 144, 24, 0.12);
  --brand-orange-glow: rgba(240, 144, 24, 0.25);
  
  --brand-charcoal: #202020;
  
  /* Fonts */
  --font-display: 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;
  --font-body: 'Inter', system-ui, -apple-system, sans-serif;
  
  /* Transitions */
  --ease-spring: cubic-bezier(0.16, 1, 0.3, 1);
  --duration-fast: 150ms;
  --duration-normal: 250ms;
}

/* Light Theme (Default) */
:root[data-theme="light"] {
  --bg-main: #F8FAFC;
  --bg-surface: #FFFFFF;
  --bg-surface-elevated: #FFFFFF;
  --bg-surface-subtle: #F1F5F9;
  --bg-card: #FFFFFF;
  --bg-card-hover: #F8FAFC;
  
  --border-subtle: #E2E8F0;
  --border-medium: #CBD5E1;
  --border-focus: #0838A0;
  
  --text-primary: #0F172A;
  --text-secondary: #334155;
  --text-muted: #64748B;
  --text-inverse: #FFFFFF;
  
  --header-glass-bg: rgba(248, 250, 252, 0.82);
  --header-glass-border: rgba(226, 232, 240, 0.85);
  
  --card-shadow: 0 4px 20px -2px rgba(15, 23, 42, 0.05), 0 2px 6px -1px rgba(15, 23, 42, 0.03);
  --card-shadow-hover: 0 20px 35px -4px rgba(8, 56, 160, 0.09), 0 6px 16px -2px rgba(15, 23, 42, 0.04);
  
  --badge-bg: rgba(8, 56, 160, 0.07);
  --badge-text: #0838A0;
  --badge-border: rgba(8, 56, 160, 0.15);

  --accent-badge-bg: rgba(240, 144, 24, 0.1);
  --accent-badge-text: #B45309;
  --accent-badge-border: rgba(240, 144, 24, 0.25);
  
  --grid-pattern: radial-gradient(rgba(15, 23, 42, 0.05) 1px, transparent 1px);
  --interactive-card-bg: #FFFFFF;
  --code-snippet-bg: #0F172A;
}

/* Dark Theme */
:root[data-theme="dark"] {
  --bg-main: #0B0F17;
  --bg-surface: #111827;
  --bg-surface-elevated: #1A2234;
  --bg-surface-subtle: #161F30;
  --bg-card: #131B2C;
  --bg-card-hover: #19243B;
  
  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-medium: rgba(255, 255, 255, 0.14);
  --border-focus: #3B82F6;
  
  --text-primary: #F8FAFC;
  --text-secondary: #CBD5E1;
  --text-muted: #94A3B8;
  --text-inverse: #0B0F17;
  
  --header-glass-bg: rgba(11, 15, 23, 0.82);
  --header-glass-border: rgba(255, 255, 255, 0.09);
  
  --card-shadow: 0 4px 24px -2px rgba(0, 0, 0, 0.4);
  --card-shadow-hover: 0 20px 40px -4px rgba(8, 56, 160, 0.28), 0 4px 16px -2px rgba(0, 0, 0, 0.6);
  
  --badge-bg: rgba(37, 99, 235, 0.15);
  --badge-text: #60A5FA;
  --badge-border: rgba(37, 99, 235, 0.3);

  --accent-badge-bg: rgba(240, 144, 24, 0.15);
  --accent-badge-text: #FBBF24;
  --accent-badge-border: rgba(240, 144, 24, 0.3);
  
  --grid-pattern: radial-gradient(rgba(255, 255, 255, 0.07) 1px, transparent 1px);
  --interactive-card-bg: #141D30;
  --code-snippet-bg: #090D14;
}

/* Base Resets */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-body);
  background-color: var(--bg-main);
  color: var(--text-primary);
  line-height: 1.6;
  transition: background-color var(--duration-normal) ease, color var(--duration-normal) ease;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

/* Glassmorphism Header */
.glass-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 50;
  background-color: var(--header-glass-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--header-glass-border);
  transition: background-color var(--duration-normal) ease, border-color var(--duration-normal) ease, box-shadow var(--duration-normal) ease;
}

.glass-header.scrolled {
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
}

/* Brand SVG Logo Adaptability */
.pixel-algos-logo-svg .logo-text-pixel {
  fill: var(--text-primary);
  transition: fill var(--duration-normal) ease;
}

.pixel-algos-logo-svg .logo-text-sub {
  fill: var(--text-secondary);
  transition: fill var(--duration-normal) ease;
}

/* Grid Background Effect */
.bg-grid-mesh {
  background-image: var(--grid-pattern);
  background-size: 28px 28px;
}

/* Card Styling */
.pa-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: 14px;
  box-shadow: var(--card-shadow);
  transition: transform var(--duration-normal) var(--ease-spring),
              border-color var(--duration-normal) ease,
              box-shadow var(--duration-normal) ease,
              background-color var(--duration-normal) ease;
}

.pa-card:hover {
  border-color: var(--border-medium);
  box-shadow: var(--card-shadow-hover);
}

.pa-card-interactive {
  position: relative;
  overflow: hidden;
}

.pa-card-interactive::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, var(--brand-blue) 0%, var(--brand-orange) 100%);
  opacity: 0;
  transition: opacity var(--duration-normal) ease;
}

.pa-card-interactive:hover::after {
  opacity: 1;
}

/* Button System */
.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  background-color: var(--brand-blue);
  color: #FFFFFF !important;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 0.95rem;
  padding: 0.85rem 1.6rem;
  border-radius: 9px;
  border: 1px solid rgba(255, 255, 255, 0.15);
  box-shadow: 0 4px 14px rgba(8, 56, 160, 0.3);
  cursor: pointer;
  transition: all var(--duration-fast) ease;
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary:hover {
  background-color: var(--brand-blue-hover);
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(8, 56, 160, 0.4);
}

.btn-primary:active {
  transform: translateY(1px);
  box-shadow: 0 2px 8px rgba(8, 56, 160, 0.3);
}

.btn-accent {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  background-color: var(--brand-orange);
  color: #FFFFFF !important;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 0.95rem;
  padding: 0.85rem 1.6rem;
  border-radius: 9px;
  border: 1px solid rgba(255, 255, 255, 0.15);
  box-shadow: 0 4px 14px rgba(240, 144, 24, 0.3);
  cursor: pointer;
  transition: all var(--duration-fast) ease;
  text-decoration: none;
  white-space: nowrap;
}

.btn-accent:hover {
  background-color: var(--brand-orange-hover);
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(240, 144, 24, 0.42);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  background-color: var(--bg-surface-subtle);
  color: var(--text-primary) !important;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 0.95rem;
  padding: 0.85rem 1.5rem;
  border-radius: 9px;
  border: 1px solid var(--border-medium);
  cursor: pointer;
  transition: all var(--duration-fast) ease;
  text-decoration: none;
  white-space: nowrap;
}

.btn-secondary:hover {
  background-color: var(--bg-surface);
  border-color: var(--brand-blue);
  color: var(--brand-blue) !important;
  transform: translateY(-1px);
}

/* Badge System */
.badge-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.35rem 0.85rem;
  font-size: 0.82rem;
  font-weight: 700;
  font-family: var(--font-display);
  letter-spacing: 0.02em;
  text-transform: uppercase;
  border-radius: 9999px;
  background-color: var(--badge-bg);
  color: var(--badge-text);
  border: 1px solid var(--badge-border);
}

.badge-accent {
  background-color: var(--accent-badge-bg);
  color: var(--accent-badge-text);
  border-color: var(--accent-badge-border);
}

/* Theme Toggle Button */
.theme-toggle-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 8px;
  background-color: var(--bg-surface-subtle);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--duration-fast) ease;
}

.theme-toggle-btn:hover {
  color: var(--brand-blue);
  border-color: var(--border-medium);
  background-color: var(--bg-surface);
}

/* Diagnostic / Calculator UI */
.diag-option-btn {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  width: 100%;
  padding: 0.9rem 1.1rem;
  border-radius: 10px;
  border: 1px solid var(--border-subtle);
  background-color: var(--bg-surface);
  color: var(--text-primary);
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 0.92rem;
  text-align: left;
  cursor: pointer;
  transition: all var(--duration-fast) ease;
}

.diag-option-btn:hover {
  border-color: var(--brand-blue);
  background-color: var(--bg-surface-subtle);
}

.diag-option-btn.active {
  border-color: var(--brand-blue);
  background-color: var(--brand-blue-subtle);
  color: var(--brand-blue);
  box-shadow: 0 0 0 1px var(--brand-blue);
}

/* Tab System */
.nav-tab-btn {
  padding: 0.75rem 1.25rem;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 0.92rem;
  border-radius: 8px;
  border: 1px solid transparent;
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  transition: all var(--duration-fast) ease;
}

.nav-tab-btn:hover {
  color: var(--text-primary);
}

.nav-tab-btn.active {
  color: var(--brand-blue);
  background-color: var(--bg-surface);
  border-color: var(--border-subtle);
  box-shadow: var(--card-shadow);
}

/* Accordion Component */
.faq-item {
  border: 1px solid var(--border-subtle);
  border-radius: 10px;
  background-color: var(--bg-card);
  overflow: hidden;
  transition: border-color var(--duration-fast) ease;
}

.faq-item:hover {
  border-color: var(--border-medium);
}

.faq-header {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.25rem 1.5rem;
  text-align: left;
  background: transparent;
  border: none;
  cursor: pointer;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--text-primary);
}

.faq-icon {
  transition: transform var(--duration-normal) ease;
  color: var(--brand-blue);
}

.faq-item.open .faq-icon {
  transform: rotate(180deg);
}

.faq-body {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease-out, padding 0.35s ease;
  padding: 0 1.5rem;
  color: var(--text-secondary);
  font-size: 0.96rem;
  line-height: 1.65;
}

.faq-item.open .faq-body {
  max-height: 300px;
  padding: 0 1.5rem 1.25rem 1.5rem;
}

/* Modal Backdrop & Container */
.modal-backdrop {
  position: fixed;
  inset: 0;
  z-index: 100;
  background-color: rgba(11, 15, 23, 0.75);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--duration-normal) ease;
}

.modal-backdrop.active {
  opacity: 1;
  pointer-events: auto;
}

.modal-dialog {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: 16px;
  width: 100%;
  max-width: 580px;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
  transform: scale(0.95) translateY(10px);
  transition: transform var(--duration-normal) var(--ease-spring);
}

.modal-backdrop.active .modal-dialog {
  transform: scale(1) translateY(0);
}

/* Form Input Styling */
.form-input, .form-select, .form-textarea {
  width: 100%;
  padding: 0.8rem 1rem;
  border-radius: 8px;
  background-color: var(--bg-surface-subtle);
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  font-family: var(--font-body);
  font-size: 0.95rem;
  outline: none;
  transition: border-color var(--duration-fast) ease, box-shadow var(--duration-fast) ease;
}

.form-input:focus, .form-select:focus, .form-textarea:focus {
  border-color: var(--brand-blue);
  box-shadow: 0 0 0 3px var(--brand-blue-subtle);
  background-color: var(--bg-surface);
}

/* Custom Scrollbar */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-main);
}

::-webkit-scrollbar-thumb {
  background: var(--border-medium);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 110;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.toast-msg {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-left: 4px solid var(--brand-blue);
  color: var(--text-primary);
  padding: 1rem 1.25rem;
  border-radius: 8px;
  box-shadow: 0 10px 25px rgba(0,0,0,0.2);
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-family: var(--font-display);
  font-size: 0.92rem;
  font-weight: 600;
  animation: slideInToast 0.3s ease forwards;
}

@keyframes slideInToast {
  from { transform: translateX(100%); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}

/* Reveal Animations */
.reveal-on-scroll {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease-out, transform 0.6s var(--ease-spring);
}

.reveal-on-scroll.revealed {
  opacity: 1;
  transform: translateY(0);
}