/* ==========================================================================
   Noakhali Tech — base.css
   Design tokens, reset, typography, layout primitives and utilities.
   ========================================================================== */

:root {
  /* Brand */
  --primary: #0B5CAD;          /* Noakhali Tech blue (logo) */
  --primary-600: #0A4F96;
  --primary-700: #083F7A;
  --primary-50: #EEF5FC;
  --primary-100: #DCEAF8;
  --accent: #F47B20;           /* Noakhali Tech orange (logo) */
  --accent-600: #DB6A12;
  --accent-50: #FFF3E9;
  --navy: #0A1B33;             /* dark sections, headings */
  --navy-800: #0F2644;
  --navy-700: #16325A;

  /* Semantic */
  --success: #16A34A;
  --success-50: #EAF7EF;
  --warning: #D97706;
  --warning-50: #FEF5E7;
  --danger: #DC2626;
  --danger-50: #FDECEC;
  --info: #0891B2;

  /* Neutrals */
  --bg: #F5F7FA;
  --bg-soft: #F9FAFC;
  --surface: #FFFFFF;
  --surface-muted: #F2F5F9;
  --border: #E3E8EF;
  --border-strong: #CFD7E2;
  --text: #0F1B2D;
  --text-2: #334155;
  --muted: #5E6E84;
  --subtle: #8A98AB;

  /* Type */
  --font: 'Plus Jakarta Sans', 'Noto Sans Bengali', 'Hind Siliguri', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  --fs-xs: .75rem;
  --fs-sm: .875rem;
  --fs-base: 1rem;
  --fs-md: 1.125rem;
  --fs-lg: 1.25rem;
  --fs-xl: 1.5rem;
  --fs-2xl: clamp(1.6rem, 1.2rem + 1.4vw, 2.25rem);
  --fs-3xl: clamp(2rem, 1.3rem + 2.6vw, 3.4rem);

  /* Shape & depth */
  --radius-sm: 8px;
  --radius: 12px;
  --radius-lg: 18px;
  --radius-xl: 26px;
  --radius-pill: 999px;
  --shadow-xs: 0 1px 2px rgba(10, 27, 51, .06);
  --shadow-sm: 0 2px 8px rgba(10, 27, 51, .06);
  --shadow: 0 10px 30px -12px rgba(10, 27, 51, .18);
  --shadow-lg: 0 24px 60px -20px rgba(10, 27, 51, .28);
  --ring: 0 0 0 4px rgba(11, 92, 173, .16);

  /* Layout */
  --container: 1320px;
  --gutter: 24px;
  --section-y: clamp(56px, 7vw, 96px);
  --header-h: 76px;
  --ease: cubic-bezier(.2, .7, .2, 1);
}

/* ---------- Reset ------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font);
  font-size: var(--fs-base);
  line-height: 1.6;
  color: var(--text);
  background: var(--surface);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}
img, svg, video { display: block; max-width: 100%; height: auto; }
a { color: inherit; text-decoration: none; }
button, input, select, textarea { font: inherit; color: inherit; }
button { cursor: pointer; background: none; border: 0; padding: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
h1, h2, h3, h4, h5, h6 { margin: 0; line-height: 1.2; font-weight: 700; color: var(--navy); letter-spacing: -.02em; }
p { margin: 0; }
figure, blockquote { margin: 0; }
table { border-collapse: collapse; width: 100%; }
:focus-visible { outline: 2px solid var(--primary); outline-offset: 2px; border-radius: 6px; }
::selection { background: var(--primary-100); }

.skip-link { position: absolute; left: 12px; top: -60px; z-index: 1000; background: var(--navy); color: #fff; padding: 10px 16px; border-radius: var(--radius-sm); }
.skip-link:focus { top: 12px; }
[hidden] { display: none !important; }
.visually-hidden { position: absolute !important; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }

/* ---------- Layout primitives ------------------------------------------ */
.container { width: 100%; max-width: var(--container); margin-inline: auto; padding-inline: var(--gutter); }
.section { padding-block: var(--section-y); }
.section--tight { padding-block: calc(var(--section-y) * .6); }
.section--muted { background: var(--bg); }
.section--dark { background: var(--navy); color: #C9D6E8; }
.section--dark h2, .section--dark h3 { color: #fff; }

.section-head { display: flex; align-items: flex-end; justify-content: space-between; gap: 24px; margin-bottom: 36px; }
.section-head--center { flex-direction: column; align-items: center; text-align: center; }
.section-head--center .section-head__sub { margin-inline: auto; }
.eyebrow { display: inline-flex; align-items: center; gap: 8px; font-size: var(--fs-xs); font-weight: 700; letter-spacing: .12em; text-transform: uppercase; color: var(--primary); margin-bottom: 12px; }
.eyebrow::before { content: ""; width: 18px; height: 2px; border-radius: 2px; background: var(--accent); }
.section--dark .eyebrow { color: #7DB8F2; }
.section-title { font-size: var(--fs-2xl); font-weight: 800; }
.section-head__sub { color: var(--muted); max-width: 620px; margin-top: 10px; font-size: var(--fs-md); }
.section--dark .section-head__sub { color: #A9B9CF; }

.grid { display: grid; gap: var(--gutter); }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.grid-6 { grid-template-columns: repeat(6, minmax(0, 1fr)); }
.stack > * + * { margin-top: 16px; }

/* ---------- Utilities --------------------------------------------------- */
.text-center { text-align: center; }
.text-muted { color: var(--muted); }
.text-primary { color: var(--primary); }
.text-accent { color: var(--accent); }
.mt-0 { margin-top: 0 !important; }
.mt-2 { margin-top: 8px; }
.mt-4 { margin-top: 16px; }
.mt-6 { margin-top: 24px; }
.mt-8 { margin-top: 32px; }
.mb-4 { margin-bottom: 16px; }
.mb-6 { margin-bottom: 24px; }
.flex { display: flex; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.justify-center { justify-content: center; }
.gap-2 { gap: 8px; }
.gap-3 { gap: 12px; }
.wrap { flex-wrap: wrap; }
.w-full { width: 100%; }
.lead { font-size: var(--fs-md); color: var(--muted); }

/* Tones shared by course covers, blog media and avatars */
.tone-blue { --tone: #0B5CAD; --tone-bg: #EAF2FC; }
.tone-orange { --tone: #E36A10; --tone-bg: #FFF1E6; }
.tone-indigo { --tone: #4F46E5; --tone-bg: #EEEEFE; }
.tone-teal { --tone: #0E8A8A; --tone-bg: #E5F6F5; }
.tone-green { --tone: #16A34A; --tone-bg: #E9F7EE; }
.tone-pink { --tone: #DB2777; --tone-bg: #FDECF4; }