/* ============================================================
   NEEDFUL CALCULATOR — Global Design System
   style.css
   ============================================================ */

/* ─── Google Fonts ─── */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=Poppins:wght@400;500;600;700;800&display=swap');

/* ─── CSS Custom Properties (Light Mode) ─── */
:root {
  /* Brand Colors */
  --clr-primary:       #2563EB;
  --clr-primary-dark:  #1D4ED8;
  --clr-primary-light: #DBEAFE;
  --clr-secondary:     #7C3AED;
  --clr-accent:        #06B6D4;
  --clr-accent-light:  #CFFAFE;

  /* Gradients */
  --gradient-brand:    linear-gradient(135deg, #2563EB 0%, #7C3AED 100%);
  --gradient-accent:   linear-gradient(135deg, #06B6D4 0%, #2563EB 100%);
  --gradient-hero:     linear-gradient(135deg, #EEF2FF 0%, #F0FDFB 50%, #FAF5FF 100%);
  --gradient-card:     linear-gradient(145deg, rgba(255,255,255,0.9) 0%, rgba(255,255,255,0.7) 100%);

  /* Surfaces */
  --bg-body:           #F8FAFC;
  --bg-surface:        #FFFFFF;
  --bg-muted:          #F1F5F9;
  --bg-glass:          rgba(255, 255, 255, 0.7);

  /* Text */
  --txt-primary:       #111827;
  --txt-secondary:     #374151;
  --txt-muted:         #6B7280;
  --txt-light:         #9CA3AF;
  --txt-inverse:       #FFFFFF;

  /* Borders */
  --border-color:      #E5E7EB;
  --border-focus:      #2563EB;

  /* Shadows */
  --shadow-sm:         0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md:         0 4px 16px rgba(0,0,0,0.08), 0 2px 6px rgba(0,0,0,0.04);
  --shadow-lg:         0 12px 40px rgba(0,0,0,0.1), 0 4px 12px rgba(0,0,0,0.06);
  --shadow-xl:         0 24px 64px rgba(0,0,0,0.12), 0 8px 24px rgba(0,0,0,0.06);
  --shadow-brand:      0 8px 32px rgba(37, 99, 235, 0.25);
  --shadow-glow:       0 0 40px rgba(37, 99, 235, 0.15);

  /* Typography */
  --font-body:         'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-heading:      'Poppins', -apple-system, BlinkMacSystemFont, sans-serif;

  --text-xs:    0.75rem;   /* 12px */
  --text-sm:    0.875rem;  /* 14px */
  --text-base:  1rem;      /* 16px */
  --text-lg:    1.125rem;  /* 18px */
  --text-xl:    1.25rem;   /* 20px */
  --text-2xl:   1.5rem;    /* 24px */
  --text-3xl:   1.875rem;  /* 30px */
  --text-4xl:   2.25rem;   /* 36px */
  --text-5xl:   3rem;      /* 48px */
  --text-6xl:   3.75rem;   /* 60px */

  /* Spacing */
  --space-1:    0.25rem;
  --space-2:    0.5rem;
  --space-3:    0.75rem;
  --space-4:    1rem;
  --space-5:    1.25rem;
  --space-6:    1.5rem;
  --space-8:    2rem;
  --space-10:   2.5rem;
  --space-12:   3rem;
  --space-16:   4rem;
  --space-20:   5rem;
  --space-24:   6rem;

  /* Border Radius */
  --radius-sm:   6px;
  --radius-md:   10px;
  --radius-lg:   14px;
  --radius-xl:   20px;
  --radius-2xl:  28px;
  --radius-full: 9999px;

  /* Transitions */
  --transition-fast:   0.15s ease;
  --transition-base:   0.25s ease;
  --transition-slow:   0.4s ease;

  /* Layout */
  --container-max:     1280px;
  --container-pad:     clamp(1rem, 5vw, 2rem);
  --header-height:     72px;

  /* Ad slots — fixed heights to prevent CLS */
  --ad-banner-h:       90px;
  --ad-rect-h:         250px;
  --ad-leaderboard-h:  90px;
}

/* ─── CSS Reset ─── */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: var(--font-body);
  font-size: var(--text-base);
  color: var(--txt-primary);
  background-color: var(--bg-body);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img, video, svg {
  display: block;
  max-width: 100%;
}

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

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

ul, ol { list-style: none; }

button {
  font-family: var(--font-body);
  cursor: pointer;
  border: none;
  background: none;
}

input, select, textarea {
  font-family: var(--font-body);
  font-size: var(--text-base);
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  line-height: 1.2;
  font-weight: 700;
  color: var(--txt-primary);
}

/* ─── Layout Utilities ─── */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--container-pad);
}

.section { padding-block: var(--space-16); }
.section-sm { padding-block: var(--space-10); }
.section-lg { padding-block: var(--space-24); }

/* Grid helpers */
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--space-6); }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--space-6); }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--space-6); }
.grid-6 { display: grid; grid-template-columns: repeat(6, 1fr); gap: var(--space-4); }

/* Flex helpers */
.flex { display: flex; }
.flex-col { display: flex; flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: var(--space-2); }
.gap-3 { gap: var(--space-3); }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }

/* Text utilities */
.text-center { text-align: center; }
.text-muted { color: var(--txt-muted); }
.text-sm { font-size: var(--text-sm); }
.text-lg { font-size: var(--text-lg); }
.font-medium { font-weight: 500; }
.font-semibold { font-weight: 600; }

/* Spacing */
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mt-8 { margin-top: var(--space-8); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }
.mb-8 { margin-bottom: var(--space-8); }

/* ─── Section Labels ─── */
.section-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--clr-primary);
  background: var(--clr-primary-light);
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-full);
  margin-bottom: var(--space-4);
}

.section-title {
  font-size: clamp(var(--text-2xl), 4vw, var(--text-4xl));
  font-weight: 800;
  color: var(--txt-primary);
  margin-bottom: var(--space-3);
  line-height: 1.15;
}

.section-subtitle {
  font-size: var(--text-lg);
  color: var(--txt-muted);
  max-width: 600px;
  margin-inline: auto;
  line-height: 1.6;
}

/* ─── Badge ─── */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: var(--text-xs);
  font-weight: 600;
  padding: 3px 10px;
  border-radius: var(--radius-full);
}
.badge-primary { background: var(--clr-primary-light); color: var(--clr-primary); }
.badge-accent   { background: var(--clr-accent-light); color: #0E7490; }
.badge-new      { background: #DCFCE7; color: #166534; }
.badge-trending { background: #FEF3C7; color: #92400E; }

/* ─── Ad Slots ─── */
.ad-slot {
  width: 100%;
  min-height: var(--ad-banner-h);
  background: var(--bg-muted);
  border: 2px dashed var(--border-color);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--txt-light);
  font-size: var(--text-sm);
  font-weight: 500;
  letter-spacing: 0.05em;
  margin-block: var(--space-6);
  overflow: hidden;
  contain: layout;
}

.ad-slot-rectangle {
  min-height: var(--ad-rect-h);
}

.ad-slot-leaderboard {
  min-height: var(--ad-leaderboard-h);
  max-width: 728px;
  margin-inline: auto;
}

/* ─── Breadcrumb ─── */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-sm);
  color: var(--txt-muted);
  flex-wrap: wrap;
  padding-block: var(--space-4);
}
.breadcrumb a { color: var(--txt-muted); }
.breadcrumb a:hover { color: var(--clr-primary); }
.breadcrumb-sep { color: var(--txt-light); }
.breadcrumb-current { color: var(--txt-primary); font-weight: 500; }

/* ─── Scrollbar ─── */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: var(--bg-muted); }
::-webkit-scrollbar-thumb { background: #CBD5E1; border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: #94A3B8; }

/* ─── Selection ─── */
::selection {
  background: var(--clr-primary-light);
  color: var(--clr-primary-dark);
}

/* ─── Focus Ring ─── */
:focus-visible {
  outline: 2px solid var(--clr-primary);
  outline-offset: 3px;
}

/* ─── Skip Link (Accessibility) ─── */
.skip-link {
  position: absolute;
  top: -100px;
  left: var(--space-4);
  background: var(--clr-primary);
  color: white;
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius-md);
  font-weight: 600;
  z-index: 9999;
  transition: top var(--transition-fast);
}
.skip-link:focus { top: var(--space-4); }

/* ─── Sticky Header Offset ─── */
.has-sticky-header {
  scroll-padding-top: calc(var(--header-height) + var(--space-4));
}

/* ─── Divider ─── */
.divider {
  height: 1px;
  background: var(--border-color);
  margin-block: var(--space-8);
}

/* ─── Visually Hidden (Screen reader only) ─── */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

/* ─── Responsive Breakpoints ─── */
@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-6 { grid-template-columns: repeat(3, 1fr); }
}

@media (max-width: 768px) {
  .grid-2, .grid-3 { grid-template-columns: 1fr; }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-6 { grid-template-columns: repeat(2, 1fr); }
  .section { padding-block: var(--space-12); }
  .section-lg { padding-block: var(--space-16); }
}

@media (max-width: 480px) {
  .grid-4, .grid-6 { grid-template-columns: 1fr; }
}