/* main.css - Core CSS and Design System for MathMaster Tools */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=JetBrains+Mono:wght@400;500;700&display=swap');

:root {
  /* Common variables */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --transition-fast: 0.15s ease;
  --transition-normal: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --border-radius-sm: 8px;
  --border-radius-md: 16px;
  --border-radius-lg: 24px;
  
  /* Default Theme: Dark Mode values (as specified in Master Prompt) */
  --bg-primary: #0b0f19;
  --bg-secondary: #111827;
  --bg-card: #1e293b;
  --bg-input: #0f172a;
  
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  
  --color-primary: #6366f1; /* Indigo-500 */
  --color-primary-hover: #4f46e5;
  --color-primary-rgb: 99, 102, 241;
  --color-secondary: #8b5cf6; /* Violet-500 */
  --color-secondary-hover: #7c3aed;
  --color-accent: #06b6d4; /* Cyan-500 */
  --color-success: #10b981;
  --color-error: #ef4444;
  --color-warning: #f59e0b;
  
  --border-color: rgba(255, 255, 255, 0.08);
  --border-focus: rgba(99, 102, 241, 0.5);
  
  --box-shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.5);
  --box-shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
  --box-shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.4), 0 10px 10px -5px rgba(0, 0, 0, 0.3);
  --box-shadow-glow: 0 0 20px rgba(99, 102, 241, 0.15);
  
  --glass-bg: rgba(30, 41, 59, 0.7);
  --glass-border: rgba(255, 255, 255, 0.08);
  --glass-blur: 12px;
}

[data-theme="light"] {
  /* Light Mode values */
  --bg-primary: #f8fafc; /* Slate-50 */
  --bg-secondary: #f1f5f9; /* Slate-100 */
  --bg-card: #ffffff;
  --bg-input: #f8fafc;
  
  --text-primary: #0f172a; /* Slate-900 */
  --text-secondary: #475569; /* Slate-600 */
  --text-muted: #94a3b8;
  
  --color-primary: #4f46e5; /* Indigo-600 */
  --color-primary-hover: #4338ca;
  --color-primary-rgb: 79, 70, 229;
  --color-secondary: #7c3aed; /* Violet-600 */
  --color-secondary-hover: #6d28d9;
  --color-accent: #0891b2;
  --color-success: #059669;
  --color-error: #dc2626;
  --color-warning: #d97706;
  
  --border-color: rgba(15, 23, 42, 0.08);
  --border-focus: rgba(79, 70, 229, 0.5);
  
  --box-shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --box-shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -1px rgba(0, 0, 0, 0.03);
  --box-shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.05), 0 4px 6px -2px rgba(0, 0, 0, 0.03);
  --box-shadow-glow: 0 0 20px rgba(79, 70, 229, 0.08);
  
  --glass-bg: rgba(255, 255, 255, 0.7);
  --glass-border: rgba(15, 23, 42, 0.08);
}

/* Reset & Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.5;
  transition: background-color var(--transition-normal), color var(--transition-normal);
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.25;
  color: var(--text-primary);
  letter-spacing: -0.025em;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

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

ul {
  list-style: none;
}

img {
  max-width: 100%;
  height: auto;
}

/* Layout Utilities */
.container {
  width: 100%;
  max-width: 1280px;
  margin-right: auto;
  margin-left: auto;
  padding-right: 1.5rem;
  padding-left: 1.5rem;
}

.grid {
  display: grid;
  gap: 1.5rem;
}

.grid-cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

@media (max-width: 1024px) {
  .grid-cols-4 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}
@media (max-width: 768px) {
  .grid-cols-3, .grid-cols-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 480px) {
  .grid-cols-2, .grid-cols-3, .grid-cols-4 { grid-template-columns: 1fr; }
}

/* Glassmorphism Classes */
.glass {
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  font-weight: 600;
  font-size: 0.95rem;
  border-radius: var(--border-radius-sm);
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  gap: 0.5rem;
  box-shadow: var(--box-shadow-sm);
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  color: #ffffff;
}

.btn-primary:hover {
  background: linear-gradient(135deg, var(--color-primary-hover), var(--color-secondary-hover));
  box-shadow: var(--box-shadow-glow);
  transform: translateY(-1px);
}

.btn-secondary {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
}

.btn-secondary:hover {
  background-color: var(--bg-secondary);
  border-color: var(--color-primary);
}

.btn-icon {
  width: 40px;
  height: 40px;
  padding: 0;
  border-radius: 50%;
}

/* Forms */
.form-group {
  margin-bottom: 1.25rem;
}

.form-label {
  display: block;
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: var(--text-secondary);
}

.form-control {
  width: 100%;
  padding: 0.75rem 1rem;
  font-size: 1rem;
  font-family: var(--font-sans);
  background-color: var(--bg-input);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-sm);
  color: var(--text-primary);
  transition: all var(--transition-fast);
}

.form-control:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--border-focus);
}

.form-checkbox {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  cursor: pointer;
  font-weight: 500;
  color: var(--text-secondary);
}

.form-checkbox input {
  width: 1.125rem;
  height: 1.125rem;
  accent-color: var(--color-primary);
  cursor: pointer;
}

/* Card Styles */
.card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: 1.5rem;
  box-shadow: var(--box-shadow-md);
  transition: transform var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.card-hover:hover {
  transform: translateY(-4px);
  border-color: rgba(var(--color-primary-rgb), 0.3);
  box-shadow: var(--box-shadow-lg), var(--box-shadow-glow);
}

/* Navigation Header */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  padding: 1rem 0;
  transition: background-color var(--transition-normal);
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-primary);
}

.logo-icon {
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  font-size: 1.75rem;
}

.logo-text span {
  font-weight: 400;
  color: var(--text-secondary);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.75rem;
}

.nav-link {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-secondary);
  position: relative;
}

.nav-link:hover, .nav-link.active {
  color: var(--text-primary);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-primary);
  transition: width var(--transition-fast);
}

.nav-link:hover::after, .nav-link.active::after {
  width: 100%;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.menu-toggle {
  display: none;
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background-color: var(--bg-card);
    border-bottom: 1px solid var(--border-color);
    padding: 1.5rem;
    flex-direction: column;
    align-items: flex-start;
    gap: 1rem;
    box-shadow: var(--box-shadow-lg);
  }
  
  .nav-links.open {
    display: flex;
  }
  
  .menu-toggle {
    display: inline-flex;
  }
}

/* Hero Section */
.hero {
  padding: 5rem 0 4rem 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero-glow {
  position: absolute;
  top: -20%;
  left: 50%;
  transform: translateX(-50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(var(--color-primary-rgb), 0.1) 0%, rgba(var(--color-primary-rgb), 0) 70%);
  z-index: -1;
  pointer-events: none;
}

.hero h1 {
  font-size: 3rem;
  font-weight: 800;
  margin-bottom: 1.25rem;
  background: linear-gradient(135deg, var(--text-primary) 30%, var(--text-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero p {
  font-size: 1.2rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto 2rem auto;
}

/* Search Box Container */
.search-container {
  position: relative;
  max-width: 580px;
  margin: 0 auto 3rem auto;
  z-index: 10;
}

.search-wrapper {
  display: flex;
  align-items: center;
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: 0.25rem 0.5rem;
  box-shadow: var(--box-shadow-md);
  transition: all var(--transition-fast);
}

.search-wrapper:focus-within {
  border-color: var(--color-primary);
  box-shadow: var(--box-shadow-glow), var(--box-shadow-lg);
}

.search-icon {
  color: var(--text-muted);
  font-size: 1.25rem;
  margin: 0 0.75rem;
}

.search-input {
  flex: 1;
  border: none;
  background: transparent;
  padding: 0.75rem 0.25rem;
  font-size: 1.05rem;
  color: var(--text-primary);
  outline: none;
}

.search-results {
  position: absolute;
  top: calc(100% + 8px);
  left: 0;
  width: 100%;
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-sm);
  box-shadow: var(--box-shadow-lg);
  display: none;
  max-height: 300px;
  overflow-y: auto;
  z-index: 50;
  text-align: left;
}

.search-results.open {
  display: block;
}

.search-item {
  padding: 0.75rem 1.25rem;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  cursor: pointer;
  transition: background-color var(--transition-fast);
}

.search-item:last-child {
  border-bottom: none;
}

.search-item:hover {
  background-color: var(--bg-secondary);
}

.search-item-title {
  font-weight: 600;
  color: var(--text-primary);
  font-size: 0.95rem;
}

.search-item-desc {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* Category Grid & Tool List */
.section-title {
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: 2rem;
  text-align: center;
  position: relative;
}

.category-section {
  padding: 3rem 0;
}

.category-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 2.5rem;
  justify-content: center;
}

.category-tab {
  padding: 0.5rem 1.25rem;
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 50px;
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  color: var(--text-secondary);
}

.category-tab:hover, .category-tab.active {
  background-color: var(--color-primary);
  color: #ffffff;
  border-color: var(--color-primary);
}

.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
}

.tool-card {
  display: flex;
  flex-direction: column;
  height: 100%;
}

.tool-card-category {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--color-primary);
  margin-bottom: 0.5rem;
  letter-spacing: 0.05em;
}

.tool-card h3 {
  font-size: 1.15rem;
  margin-bottom: 0.75rem;
}

.tool-card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  flex-grow: 1;
  margin-bottom: 1.25rem;
}

.tool-card-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  color: var(--color-primary);
  font-weight: 600;
}

/* Tool Layout Specific (Breadcrumbs, Sidebar, Tool container) */
.breadcrumbs {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 1.5rem;
  margin-bottom: 1.5rem;
}

.breadcrumbs a {
  color: var(--text-secondary);
}

.breadcrumbs a:hover {
  color: var(--color-primary);
}

.tool-layout {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 2rem;
  margin-bottom: 4rem;
}

@media (max-width: 968px) {
  .tool-layout {
    grid-template-columns: 1fr;
  }
}

.tool-main {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.tool-formula {
  background-color: var(--bg-secondary);
  padding: 1.25rem;
  border-radius: var(--border-radius-sm);
  border-left: 4px solid var(--color-primary);
  font-family: var(--font-mono);
  overflow-x: auto;
  font-size: 0.95rem;
}

.tool-sidebar {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.sidebar-widget {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: 1.25rem;
}

.sidebar-widget h4 {
  font-size: 1rem;
  margin-bottom: 1rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.5rem;
}

.related-tools-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.related-tool-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.related-tool-link:hover {
  color: var(--color-primary);
}

/* Calculator specific controls/actions */
.calculator-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.5rem;
}

.result-area {
  margin-top: 2rem;
  border-top: 1px solid var(--border-color);
  padding-top: 1.5rem;
  display: none;
}

.result-area.active {
  display: block;
}

.result-card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-sm);
  padding: 1.5rem;
  margin-bottom: 1rem;
}

.result-label {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
  letter-spacing: 0.05em;
}

.result-value {
  font-family: var(--font-mono);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
  word-break: break-all;
}

.explanation-card {
  margin-top: 1.5rem;
}

.explanation-card h3 {
  font-size: 1.25rem;
  margin-bottom: 1rem;
}

.explanation-steps {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-top: 1rem;
}

.step-item {
  display: flex;
  gap: 1rem;
  align-items: flex-start;
}

.step-number {
  background-color: var(--color-primary);
  color: #ffffff;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: 700;
  flex-shrink: 0;
}

.step-text {
  font-size: 0.95rem;
  color: var(--text-secondary);
}

/* Utility Info Page Layout */
.info-layout {
  max-width: 800px;
  margin: 3rem auto;
  padding: 0 1.5rem;
}

.info-layout h1 {
  font-size: 2.5rem;
  margin-bottom: 1.5rem;
  text-align: center;
}

.info-layout h2 {
  font-size: 1.75rem;
  margin: 2rem 0 1rem 0;
}

.info-layout p {
  color: var(--text-secondary);
  margin-bottom: 1.25rem;
  font-size: 1.05rem;
}

.info-layout ul, .info-layout ol {
  margin-bottom: 1.5rem;
  padding-left: 1.5rem;
  color: var(--text-secondary);
}

.info-layout li {
  margin-bottom: 0.5rem;
}

/* Back to Top & Floating components */
.back-to-top {
  position: fixed;
  bottom: 24px;
  right: 24px;
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  width: 48px;
  height: 48px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  z-index: 99;
  box-shadow: var(--box-shadow-md);
  transition: all var(--transition-fast);
  opacity: 0;
  visibility: hidden;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  transform: translateY(-4px);
  border-color: var(--color-primary);
  box-shadow: var(--box-shadow-lg), var(--box-shadow-glow);
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  bottom: 24px;
  left: 24px;
  z-index: 1000;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.toast {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-left: 4px solid var(--color-success);
  border-radius: var(--border-radius-sm);
  padding: 0.75rem 1.25rem;
  color: var(--text-primary);
  box-shadow: var(--box-shadow-lg);
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  transform: translateX(-120%);
  transition: transform var(--transition-normal);
  max-width: 320px;
}

.toast.show {
  transform: translateX(0);
}

.toast-error {
  border-left-color: var(--color-error);
}

/* Accordion FAQ */
.accordion {
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  overflow: hidden;
  margin-top: 1.5rem;
}

.accordion-item {
  border-bottom: 1px solid var(--border-color);
}

.accordion-item:last-child {
  border-bottom: none;
}

.accordion-header {
  padding: 1.25rem 1.5rem;
  background-color: var(--bg-card);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 600;
  transition: background-color var(--transition-fast);
}

.accordion-header:hover {
  background-color: var(--bg-secondary);
}

.accordion-icon {
  transition: transform var(--transition-fast);
  font-size: 1.25rem;
}

.accordion-content {
  padding: 0;
  max-height: 0;
  overflow: hidden;
  background-color: var(--bg-primary);
  transition: max-height var(--transition-normal), padding var(--transition-normal);
}

.accordion-item.active .accordion-content {
  padding: 1.25rem 1.5rem;
  max-height: 300px;
}

.accordion-item.active .accordion-icon {
  transform: rotate(180deg);
}

/* Footer Styles */
.footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 4rem 0 2rem 0;
  margin-top: 6rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr repeat(3, 1fr);
  gap: 3rem;
  margin-bottom: 3rem;
}

@media (max-width: 768px) {
  .footer-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }
}

.footer-about h3 {
  font-size: 1.25rem;
  margin-bottom: 1rem;
}

.footer-about p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: 1.5rem;
}

.footer-socials {
  display: flex;
  gap: 1rem;
}

.footer-social-link {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  transition: all var(--transition-fast);
}

.footer-social-link:hover {
  background-color: var(--color-primary);
  color: #ffffff;
  border-color: var(--color-primary);
}

.footer-column h4 {
  font-size: 1rem;
  margin-bottom: 1.25rem;
  color: var(--text-primary);
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.footer-link {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.footer-link:hover {
  color: var(--color-primary);
}

.footer-bottom {
  border-top: 1px solid var(--border-color);
  padding-top: 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  color: var(--text-muted);
}

@media (max-width: 640px) {
  .footer-bottom {
    flex-direction: column;
    gap: 1rem;
    text-align: center;
  }
}

/* Spinner Loader */
.loader-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: var(--bg-primary);
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: opacity 0.5s ease, visibility 0.5s ease;
}

.loader {
  width: 50px;
  height: 50px;
  border: 4px solid var(--border-color);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* Accessibility */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}