/* ==========================================================================
   base.css — design tokens, reset, typography, layout primitives
   Single source of truth for colour, type and spacing across the site.
   Tokens extracted from the original conference page so pages don't drift.
   ========================================================================== */

:root{
  /* Brand palette — sampled from the NeuroSense logo and seminar flyer */
  --navy:      #1a1550;
  --navy-deep: #241946;
  --purple:    #6b3fa0;
  --teal:      #1a8f96;
  --orange:    #f2883f;
  --orange-hot:#ef6427;
  --pink:      #e0507a;
  --green:     #4caf50;

  --rainbow: linear-gradient(90deg,#1a8f96,#f2883f,#e0507a,#6b3fa0,#4caf50);

  /* Surfaces & text */
  --bg:        #f7f5fb;
  --surface:   #ffffff;
  --text:      #1a1550;
  --muted:     #5a5470;
  --line:      #e7e0f5;

  /* Typography */
  --font-body: 'Source Sans 3', 'Segoe UI', Arial, sans-serif;
  --font-head: 'Poppins', 'Segoe UI', Arial, sans-serif;

  --fs-xs: 0.8125rem;   /* 13px */
  --fs-sm: 0.9375rem;   /* 15px */
  --fs-base: 1.0625rem; /* 17px */
  --fs-lg: 1.25rem;     /* 20px */
  --fs-h3: 1.35rem;
  --fs-h2: 1.75rem;
  --fs-h1: 2.625rem;

  /* Spacing scale */
  --sp-1: 6px;
  --sp-2: 12px;
  --sp-3: 18px;
  --sp-4: 24px;
  --sp-5: 32px;
  --sp-6: 48px;
  --sp-7: 64px;

  --radius:   14px;
  --radius-sm: 8px;
  --radius-pill: 24px;

  --shadow: 0 2px 10px rgba(36,25,70,0.06);

  --maxw: 1000px;
}

*{ box-sizing: border-box; }

html{ -webkit-text-size-adjust: 100%; }

body{
  margin: 0;
  font-family: var(--font-body);
  font-size: var(--fs-base);
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
}

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

a{ color: var(--purple); }
a:hover{ color: var(--navy); }

h1,h2,h3,h4{
  font-family: var(--font-head);
  line-height: 1.2;
  color: var(--navy-deep);
  margin: 0 0 var(--sp-2);
}
h1{ font-size: var(--fs-h1); }
h2{ font-size: var(--fs-h2); }
h3{ font-size: var(--fs-h3); }

p{ margin: 0 0 var(--sp-2); }

/* Layout primitives ------------------------------------------------------- */

.container{
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 var(--sp-4);
}

section{ padding: var(--sp-6) 0; }
section.tight{ padding: var(--sp-5) 0; }
section.alt{ background: var(--surface); }

.muted{ color: var(--muted); }
.small{ font-size: var(--fs-sm); }
.center{ text-align: center; }
.stack > * + *{ margin-top: var(--sp-3); }

/* Section heading with the brand accent bar */
.section-title{
  border-left: 6px solid var(--orange);
  padding-left: var(--sp-2);
  margin-bottom: var(--sp-4);
}

/* Accessibility ----------------------------------------------------------- */

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

.skip-link{
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--navy-deep);
  color: #fff;
  padding: var(--sp-2) var(--sp-3);
  z-index: 100;
}
.skip-link:focus{ left: var(--sp-2); top: var(--sp-2); }

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

@media (prefers-reduced-motion: reduce){
  *{ animation: none !important; transition: none !important; scroll-behavior: auto !important; }
}

/* Responsive type --------------------------------------------------------- */
@media (max-width: 640px){
  :root{ --fs-h1: 2rem; --fs-h2: 1.5rem; }
}