/* ============================================================
   ZEELCHEM™ Design System — Foundation
   Premium Industrial Water Treatment Chemicals Website
   ============================================================ */

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

:root {
  /* ── Color System ── */
  --color-bg-primary: #0a1628;
  --color-bg-secondary: #0d1b2a;
  --color-bg-tertiary: #1b2838;
  --color-bg-card: #162032;
  --color-bg-card-hover: #1e2d45;
  --color-bg-elevated: #1a2940;
  --color-surface: rgba(255, 255, 255, 0.03);
  --color-surface-hover: rgba(255, 255, 255, 0.06);

  --color-border: rgba(255, 255, 255, 0.08);
  --color-border-hover: rgba(255, 255, 255, 0.15);
  --color-border-active: rgba(255, 255, 255, 0.25);

  --color-text-primary: #f8fafc;
  --color-text-secondary: #94a3b8;
  --color-text-muted: #64748b;
  --color-text-inverse: #0a1628;

  /* Brand Colors */
  --color-primary: #0ea5e9;
  --color-primary-light: #38bdf8;
  --color-primary-dark: #0284c7;
  --color-primary-glow: rgba(14, 165, 233, 0.2);

  --color-accent: #00d4ff;
  --color-accent-light: #67e8f9;
  --color-accent-dark: #00a8cc;
  --color-accent-glow: rgba(0, 212, 255, 0.15);

  --color-gold: #fbbf24;
  --color-gold-light: #fcd34d;
  --color-gold-dark: #f59e0b;
  --color-gold-glow: rgba(251, 191, 36, 0.15);

  --color-green: #34d399;
  --color-green-light: #6ee7b7;
  --color-green-dark: #10b981;
  --color-green-glow: rgba(52, 211, 153, 0.15);

  --color-rose: #fb7185;
  --color-rose-light: #fda4af;
  --color-rose-dark: #f43f5e;
  --color-rose-glow: rgba(251, 113, 133, 0.15);

  --color-purple: #a78bfa;
  --color-purple-glow: rgba(167, 139, 250, 0.15);

  /* Gradients */
  --gradient-hero: linear-gradient(135deg, #0a1628 0%, #0d2847 40%, #0f1d32 100%);
  --gradient-card: linear-gradient(145deg, var(--color-bg-card) 0%, rgba(22, 32, 50, 0.8) 100%);
  --gradient-primary: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
  --gradient-gold: linear-gradient(135deg, var(--color-gold) 0%, #f59e0b 100%);
  --gradient-text: linear-gradient(90deg, #ffffff 0%, #38bdf8 30%, #00d4ff 60%, #fbbf24 100%);
  --gradient-section-dark: linear-gradient(180deg, var(--color-bg-primary) 0%, var(--color-bg-secondary) 100%);
  --gradient-section-alt: linear-gradient(180deg, var(--color-bg-secondary) 0%, var(--color-bg-tertiary) 50%, var(--color-bg-secondary) 100%);
  --gradient-glow-cyan: radial-gradient(ellipse at center, rgba(0, 212, 255, 0.08) 0%, transparent 70%);
  --gradient-glow-gold: radial-gradient(ellipse at center, rgba(251, 191, 36, 0.06) 0%, transparent 70%);

  /* ── Typography ── */
  --font-heading: 'Montserrat', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;

  /* Font Sizes — Fluid Typography */
  --text-xs: clamp(0.7rem, 0.65rem + 0.25vw, 0.75rem);
  --text-sm: clamp(0.8rem, 0.75rem + 0.25vw, 0.875rem);
  --text-base: clamp(0.9rem, 0.85rem + 0.25vw, 1rem);
  --text-md: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
  --text-lg: clamp(1.1rem, 1rem + 0.5vw, 1.25rem);
  --text-xl: clamp(1.2rem, 1.1rem + 0.5vw, 1.5rem);
  --text-2xl: clamp(1.4rem, 1.2rem + 1vw, 1.875rem);
  --text-3xl: clamp(1.6rem, 1.3rem + 1.5vw, 2.25rem);
  --text-4xl: clamp(1.8rem, 1.4rem + 2vw, 3rem);
  --text-5xl: clamp(2rem, 1.5rem + 2.5vw, 3.75rem);

  --leading-tight: 1.2;
  --leading-snug: 1.35;
  --leading-normal: 1.6;
  --leading-relaxed: 1.75;

  --tracking-tight: -0.025em;
  --tracking-normal: 0;
  --tracking-wide: 0.025em;
  --tracking-wider: 0.05em;
  --tracking-widest: 0.1em;

  /* Font Weights */
  --weight-regular: 400;
  --weight-medium: 500;
  --weight-semibold: 600;
  --weight-bold: 700;
  --weight-extrabold: 800;

  /* ── Spacing ── */
  --space-3xs: 0.125rem;   /* 2px */
  --space-2xs: 0.25rem;    /* 4px */
  --space-xs: 0.5rem;      /* 8px */
  --space-sm: 0.75rem;     /* 12px */
  --space-md: 1rem;        /* 16px */
  --space-lg: 1.5rem;      /* 24px */
  --space-xl: 2rem;        /* 32px */
  --space-2xl: 3rem;       /* 48px */
  --space-3xl: 4rem;       /* 64px */
  --space-4xl: 6rem;       /* 96px */
  --space-5xl: 8rem;       /* 128px */

  /* ── Border Radius ── */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-2xl: 32px;
  --radius-full: 9999px;

  /* ── Shadows ── */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3), 0 1px 2px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.3), 0 2px 4px rgba(0, 0, 0, 0.2);
  --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.35), 0 5px 10px rgba(0, 0, 0, 0.2);
  --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.4), 0 10px 20px rgba(0, 0, 0, 0.25);
  --shadow-2xl: 0 30px 60px rgba(0, 0, 0, 0.5);
  --shadow-glow-cyan: 0 0 20px rgba(0, 212, 255, 0.15), 0 0 40px rgba(0, 212, 255, 0.08);
  --shadow-glow-gold: 0 0 20px rgba(251, 191, 36, 0.15), 0 0 40px rgba(251, 191, 36, 0.08);
  --shadow-glow-primary: 0 0 20px rgba(14, 165, 233, 0.2), 0 0 40px rgba(14, 165, 233, 0.1);
  --shadow-card: 0 4px 16px rgba(0, 0, 0, 0.3), 0 0 0 1px var(--color-border);
  --shadow-card-hover: 0 8px 30px rgba(0, 0, 0, 0.4), 0 0 0 1px var(--color-border-hover), var(--shadow-glow-cyan);

  /* ── Transitions ── */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 400ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-spring: 500ms cubic-bezier(0.34, 1.56, 0.64, 1);

  /* ── Z-Index Scale ── */
  --z-behind: -1;
  --z-base: 0;
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-overlay: 300;
  --z-modal: 400;
  --z-toast: 500;
  --z-floating: 600;

  /* ── Layout ── */
  --container-sm: 640px;
  --container-md: 768px;
  --container-lg: 1024px;
  --container-xl: 1200px;
  --container-2xl: 1400px;
  --header-height: 72px;
  --header-height-scrolled: 60px;
}

/* ── Base Styles ── */
html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-padding-top: calc(var(--header-height) + var(--space-lg));
}

body {
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-regular);
  line-height: var(--leading-normal);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  min-height: 100vh;
}

/* ── Typography Base ── */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: var(--weight-bold);
  line-height: var(--leading-tight);
  letter-spacing: var(--tracking-tight);
  color: var(--color-text-primary);
}

h1 { font-size: var(--text-4xl); font-weight: var(--weight-extrabold); }
h2 { font-size: var(--text-3xl); }
h3 { font-size: var(--text-2xl); }
h4 { font-size: var(--text-xl); font-weight: var(--weight-semibold); }
h5 { font-size: var(--text-lg); font-weight: var(--weight-semibold); }
h6 { font-size: var(--text-md); font-weight: var(--weight-semibold); }

p {
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  max-width: 72ch;
}

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

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

a:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

strong { font-weight: var(--weight-semibold); color: var(--color-text-primary); }

ul, ol { list-style: none; }

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

button {
  cursor: pointer;
  font-family: inherit;
  border: none;
  background: none;
  color: inherit;
}

input, select, textarea {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
}

table {
  border-collapse: collapse;
  width: 100%;
}

/* ── Skip Link (Accessibility) ── */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-md);
  padding: var(--space-xs) var(--space-md);
  background: var(--color-accent);
  color: var(--color-text-inverse);
  font-weight: var(--weight-semibold);
  border-radius: 0 0 var(--radius-md) var(--radius-md);
  z-index: var(--z-toast);
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 0;
  outline: none;
}

/* ── Container ── */
.container {
  width: 100%;
  max-width: var(--container-xl);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

@media (min-width: 768px) {
  .container { padding: 0 var(--space-xl); }
}

@media (min-width: 1024px) {
  .container { padding: 0 var(--space-2xl); }
}

.container-narrow {
  max-width: var(--container-lg);
}

/* ── Section Spacing ── */
.section {
  padding: var(--space-3xl) 0;
  position: relative;
}

.section-lg {
  padding: var(--space-4xl) 0;
}

.section-dark {
  background: var(--gradient-section-dark);
}

.section-alt {
  background: var(--gradient-section-alt);
}

.section-accent {
  background: var(--color-bg-tertiary);
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}

/* ── Section Headers ── */
.section-label {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  font-family: var(--font-heading);
  font-size: var(--text-xs);
  font-weight: var(--weight-bold);
  text-transform: uppercase;
  letter-spacing: var(--tracking-widest);
  color: var(--color-accent);
  margin-bottom: var(--space-md);
}

.section-label::before {
  content: '';
  width: 24px;
  height: 2px;
  background: var(--gradient-primary);
  border-radius: var(--radius-full);
}

.section-title {
  margin-bottom: var(--space-md);
}

.section-subtitle {
  font-size: var(--text-lg);
  color: var(--color-text-secondary);
  max-width: 640px;
}

.text-center { text-align: center; }
.text-center .section-label { justify-content: center; }
.text-center .section-subtitle { margin-left: auto; margin-right: auto; }

/* ── Grid System ── */
.grid {
  display: grid;
  gap: var(--space-lg);
}

.grid-2 { grid-template-columns: 1fr; }
.grid-3 { grid-template-columns: 1fr; }
.grid-4 { grid-template-columns: 1fr; }

@media (min-width: 640px) {
  .grid-2 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
}

@media (min-width: 1024px) {
  .grid-3 { grid-template-columns: repeat(3, 1fr); }
  .grid-4 { grid-template-columns: repeat(4, 1fr); }
}

/* ── Utility Classes ── */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-xs { gap: var(--space-xs); }
.gap-sm { gap: var(--space-sm); }
.gap-md { gap: var(--space-md); }
.gap-lg { gap: var(--space-lg); }
.gap-xl { gap: var(--space-xl); }

.mt-sm { margin-top: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mt-xl { margin-top: var(--space-xl); }
.mt-2xl { margin-top: var(--space-2xl); }
.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.mb-xl { margin-bottom: var(--space-xl); }

/* ── Selection ── */
::selection {
  background: var(--color-accent);
  color: var(--color-text-inverse);
}

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

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

::-webkit-scrollbar-thumb {
  background: var(--color-bg-tertiary);
  border-radius: var(--radius-full);
  border: 2px solid var(--color-bg-secondary);
}

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

/* ── Focus Styles ── */
:focus {
  outline: none;
}

:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}

/* ── Print Styles ── */
@media print {
  body {
    background: white;
    color: black;
  }

  .site-header, .site-footer, .floating-cta, .btn {
    display: none !important;
  }
}