/* =========================================================
   main.css — Professor Dr. S.M.G. Kibria
   Design System Foundation | Bear My Brand
   ========================================================= */

/* -----------------------------
   1. Design Tokens
----------------------------- */
:root {
  /* Primary Blues */
  --blue-900:  #0a2e50;
  --blue-800:  #0f4a7a;
  --blue-700:  #1867a6;
  --blue-600:  #2180cc;
  --blue-500:  #3d9be0;
  --blue-200:  #a8cfed;
  --blue-100:  #daeaf8;
  --blue-50:   #f0f7ff;

  /* Gold */
  --gold-700:  #9a6f20;
  --gold-500:  #c9a84c;
  --gold-300:  #e8c97a;
  --gold-100:  #f9f0d6;

  /* Neutrals */
  --gray-900:  #111827;
  --gray-800:  #1f2937;
  --gray-700:  #374151;
  --gray-500:  #6b7280;
  --gray-400:  #9ca3af;
  --gray-300:  #d1d5db;
  --gray-200:  #e5e7eb;
  --gray-100:  #f3f4f6;
  --white:     #ffffff;

  /* Semantic surfaces */
  --surface-0: #ffffff;
  --surface-1: #f8fafd;
  --surface-2: #f0f7ff;
  --border:    #dde8f4;

  /* Shadows */
  --shadow-sm:   0 2px 8px rgba(24,103,166,0.08);
  --shadow-md:   0 8px 32px rgba(24,103,166,0.12);
  --shadow-lg:   0 20px 64px rgba(24,103,166,0.16);
  --shadow-gold: 0 4px 24px rgba(201,168,76,0.25);
  --glow-blue:   0 0 40px rgba(24,103,166,0.40);
  --glow-gold:   0 0 30px rgba(201,168,76,0.40);

  /* Typography — clean, bold, corporate */
  --font-serif: 'Manrope', 'Inter', -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
  --font-sans:  'Inter', -apple-system, BlinkMacSystemFont, system-ui, sans-serif;

  --text-xs:   0.75rem;
  --text-sm:   0.875rem;
  --text-base: 1rem;
  --text-lg:   1.125rem;
  --text-xl:   1.25rem;
  --text-2xl:  1.5rem;
  --text-3xl:  1.875rem;
  --text-4xl:  2.25rem;
  --text-5xl:  3rem;
  --text-6xl:  3.75rem;
  --text-7xl:  4.5rem;

  --leading-tight:   1.2;
  --leading-snug:    1.375;
  --leading-normal:  1.6;
  --leading-relaxed: 1.75;

  /* Layout */
  --container-max: 1240px;
  --container-pad: clamp(16px, 5vw, 80px);
  --section-py:    clamp(60px, 8vw, 120px);
  --gap-grid:      clamp(16px, 2.5vw, 32px);

  /* Radii */
  --radius-sm:   8px;
  --radius-md:   12px;
  --radius-lg:   20px;
  --radius-xl:   32px;
  --radius-full: 9999px;

  /* Motion */
  --ease-out:    cubic-bezier(0.16, 1, 0.3, 1);
  --ease-bounce: cubic-bezier(0.34, 1.56, 0.64, 1);
  --dur-fast:    0.18s;
  --dur-base:    0.3s;
  --dur-slow:    0.6s;

  /* Z-index */
  --z-nav:       1000;
  --z-overlay:   1050;
  --z-modal:     1100;
  --z-tooltip:   1200;
}

/* -----------------------------
   2. Modern CSS Reset
----------------------------- */
*, *::before, *::after { box-sizing: border-box; }

* { margin: 0; padding: 0; }

html {
  -webkit-text-size-adjust: 100%;
  -moz-tab-size: 4;
  tab-size: 4;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--gray-900);
  background: var(--white);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

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

input, button, textarea, select { font: inherit; color: inherit; }

button {
  background: none;
  border: none;
  cursor: pointer;
}

a {
  color: var(--blue-700);
  text-decoration: none;
  transition: color var(--dur-base) var(--ease-out);
}

a:hover { color: var(--blue-600); }

ul, ol { list-style: none; }

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-serif);
  font-weight: 800;
  line-height: var(--leading-snug);
  letter-spacing: -0.02em;
  color: var(--gray-900);
}

p { color: var(--gray-700); line-height: var(--leading-relaxed); }

/* Accessibility */
:focus-visible {
  outline: 3px solid var(--gold-500);
  outline-offset: 2px;
  border-radius: 4px;
}

.skip-link {
  position: absolute;
  top: -60px;
  left: 16px;
  background: var(--blue-700);
  color: var(--white);
  padding: 10px 18px;
  z-index: var(--z-modal);
  border-radius: 0 0 6px 6px;
  transition: top var(--dur-base);
}
.skip-link:focus { top: 0; color: var(--white); }

.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;
}

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

.section {
  padding-block: var(--section-py);
  position: relative;
}

.section--surface { background: var(--surface-1); }
.section--blue    { background: var(--blue-700); color: var(--white); }
.section--dark    {
  background: linear-gradient(135deg, var(--blue-900) 0%, var(--blue-800) 100%);
  color: var(--white);
}

.section__head {
  max-width: 760px;
  margin-inline: auto;
  text-align: center;
  margin-bottom: clamp(40px, 5vw, 72px);
}

.section__eyebrow {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--gold-500);
  margin-bottom: 14px;
}

.section__title {
  font-family: var(--font-serif);
  font-size: clamp(var(--text-3xl), 3.5vw, var(--text-5xl));
  line-height: var(--leading-tight);
  letter-spacing: -0.015em;
  margin-bottom: 16px;
}

.section__title--light { color: var(--white); }

.section__subtitle {
  font-size: var(--text-lg);
  color: var(--gray-500);
  line-height: var(--leading-relaxed);
}

.section__subtitle--light { color: rgba(255,255,255,0.78); }

/* -----------------------------
   4. Typography Utilities
----------------------------- */
.display-heading {
  font-family: var(--font-serif);
  font-size: clamp(var(--text-4xl), 5.5vw, var(--text-7xl));
  font-weight: 700;
  line-height: 1.08;
  letter-spacing: -0.02em;
}

.eyebrow {
  font-family: var(--font-sans);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.2em;
  text-transform: uppercase;
}

.text-gold { color: var(--gold-500); }
.text-blue { color: var(--blue-700); }
.text-white { color: var(--white); }
.text-muted { color: var(--gray-500); }

/* -----------------------------
   5. Buttons
----------------------------- */
.btn {
  --btn-bg: var(--blue-700);
  --btn-color: var(--white);
  --btn-border: var(--blue-700);

  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 16px 32px;
  font-family: var(--font-sans);
  font-size: var(--text-base);
  font-weight: 600;
  letter-spacing: 0.01em;
  line-height: 1;
  background: var(--btn-bg);
  color: var(--btn-color);
  border: 2px solid var(--btn-border);
  border-radius: var(--radius-full);
  cursor: pointer;
  position: relative;
  overflow: hidden;
  transition: transform var(--dur-base) var(--ease-out),
              box-shadow var(--dur-base) var(--ease-out),
              background var(--dur-base) var(--ease-out),
              color var(--dur-base) var(--ease-out);
  text-decoration: none;
  white-space: nowrap;
}

.btn::after {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(255,255,255,0.15);
  transform: translateX(-100%);
  transition: transform 0.4s var(--ease-out);
  pointer-events: none;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  color: var(--btn-color);
}
.btn:hover::after { transform: translateX(0); }

.btn:active { transform: translateY(0); }

.btn--gold {
  --btn-bg: var(--gold-500);
  --btn-color: var(--gray-900);
  --btn-border: var(--gold-500);
  box-shadow: var(--shadow-gold);
}
.btn--gold:hover {
  --btn-bg: var(--gold-300);
  --btn-border: var(--gold-300);
  box-shadow: var(--glow-gold);
}

.btn--outline {
  --btn-bg: transparent;
  --btn-color: var(--white);
  --btn-border: rgba(255,255,255,0.4);
}
.btn--outline:hover {
  --btn-bg: rgba(255,255,255,0.08);
  --btn-border: var(--white);
}

.btn--outline-dark {
  --btn-bg: transparent;
  --btn-color: var(--blue-700);
  --btn-border: var(--blue-700);
}
.btn--outline-dark:hover {
  --btn-bg: var(--blue-700);
  --btn-color: var(--white);
}

.btn--ghost {
  --btn-bg: transparent;
  --btn-color: var(--blue-700);
  --btn-border: transparent;
  padding: 12px 20px;
}
.btn--ghost:hover {
  --btn-bg: var(--blue-50);
}

.btn--sm { padding: 12px 22px; font-size: var(--text-sm); }
.btn--lg { padding: 20px 40px; font-size: var(--text-lg); }

.btn__arrow {
  transition: transform var(--dur-base) var(--ease-out);
}
.btn:hover .btn__arrow { transform: translateX(4px); }

/* -----------------------------
   6. Utility Helpers
----------------------------- */
.u-sr-only { position: absolute !important; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0; }
.u-flex { display: flex; }
.u-grid { display: grid; }
.u-hidden { display: none !important; }

@media (max-width: 767px) {
  .u-hide-mobile { display: none !important; }
}
@media (min-width: 768px) {
  .u-show-mobile { display: none !important; }
}

/* -----------------------------
   7. Reduced Motion
----------------------------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}