/* immunesystemday.com — bright public-health campaign.
   Vital teal + warm coral on cream · Bricolage Grotesque + Hanken Grotesk. */

:root {
  --cream:   oklch(0.984 0.012 95);
  --cream-2: oklch(0.962 0.022 120);     /* soft mint panel */
  --ink:     oklch(0.30 0.045 200);      /* deep teal-ink text */
  --ink-soft:oklch(0.46 0.040 200);
  --teal:    oklch(0.62 0.115 195);
  --teal-deep: oklch(0.46 0.105 200);
  --coral:   oklch(0.68 0.165 32);
  --coral-deep: oklch(0.60 0.165 30);
  --line:    oklch(0.30 0.045 200 / 0.14);
  --white:   oklch(0.995 0.004 95);

  --maxw: 74rem;
  --step--1: clamp(0.88rem, 0.85rem + 0.15vw, 0.96rem);
  --step-0:  clamp(1.05rem, 1.00rem + 0.28vw, 1.20rem);
  --step-1:  clamp(1.28rem, 1.15rem + 0.6vw, 1.6rem);
  --step-2:  clamp(1.7rem, 1.4rem + 1.4vw, 2.55rem);
  --step-3:  clamp(2.2rem, 1.7rem + 2.4vw, 3.6rem);
  --step-4:  clamp(2.7rem, 1.9rem + 3.9vw, 5rem);
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

body {
  margin: 0;
  background: var(--cream);
  color: var(--ink);
  font-family: "Hanken Grotesk", system-ui, sans-serif;
  font-size: var(--step-0);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; display: block; }
::selection { background: var(--coral); color: var(--white); }

.skip-link { position: absolute; left: -9999px; top: 0; z-index: 100; background: var(--ink); color: var(--cream); padding: .7em 1.1em; }
.skip-link:focus { left: 0; }

h1, h2, h3 { font-family: "Bricolage Grotesque", system-ui, sans-serif; font-weight: 700; line-height: 1.05; letter-spacing: -0.015em; }

.eyebrow {
  font-family: "Bricolage Grotesque", sans-serif;
  font-size: var(--step--1); font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.14em;
  color: var(--coral-deep); margin: 0 0 0.8rem;
}
.eyebrow--teal { color: var(--teal-deep); }
.eyebrow--coral { color: var(--coral-deep); }

.section-title { font-size: var(--step-3); margin: 0; color: var(--ink); }
.section-head { max-width: 40rem; margin: 0 0 clamp(2rem,4vw,3rem); }
.section-head--center { margin-left: auto; margin-right: auto; text-align: center; }

/* buttons */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  font-family: "Bricolage Grotesque", sans-serif; font-weight: 600;
  font-size: var(--step-0); padding: 0.85em 1.6em; border-radius: 999px;
  text-decoration: none; border: 2px solid transparent; cursor: pointer;
  transition: transform .35s var(--ease), background-color .25s var(--ease), color .25s var(--ease), border-color .25s var(--ease);
}
.btn--sm { font-size: var(--step--1); padding: 0.6em 1.1em; }
.btn--lg { font-size: var(--step-1); padding: 0.95em 2em; }
.btn:hover { transform: translateY(-2px); }
.btn--coral { background: var(--coral); color: var(--white); }
.btn--coral:hover { background: var(--coral-deep); }
.btn--ghost { background: transparent; color: var(--ink); border-color: var(--line); }
.btn--ghost:hover { border-color: var(--teal-deep); color: var(--teal-deep); }

/* header */
.site-header { position: sticky; top: 0; z-index: 50; background: oklch(0.984 0.012 95 / 0.85); backdrop-filter: saturate(1.3) blur(10px); border-bottom: 1px solid var(--line); }
.nav { max-width: var(--maxw); margin: 0 auto; display: flex; align-items: center; gap: 1.2rem; padding: 0.8rem clamp(1.1rem,4vw,2.5rem); }
.nav__brand { margin-right: auto; display: inline-flex; }
.nav__brand img { height: 2.3rem; width: auto; }
.nav__links { display: flex; align-items: center; gap: clamp(1rem,2vw,1.9rem); list-style: none; margin: 0; padding: 0; }
.nav__links a { text-decoration: none; color: var(--ink-soft); font-weight: 500; font-size: var(--step--1); }
.nav__links a:not(.btn):hover { color: var(--teal-deep); }
.nav__toggle { display: none; flex-direction: column; gap: 5px; background: none; border: 0; cursor: pointer; padding: 8px; }
.nav__toggle span { width: 24px; height: 2px; background: var(--ink); border-radius: 2px; transition: transform .3s var(--ease), opacity .3s; }
@media (max-width: 780px) {
  .nav__toggle { display: flex; }
  .nav__links {
    position: absolute; top: 100%; left: 0; right: 0; flex-direction: column; align-items: flex-start;
    gap: 1rem; background: var(--cream); border-bottom: 1px solid var(--line);
    padding: 1.2rem clamp(1.1rem,4vw,2.5rem) 1.6rem;
    display: grid; grid-template-rows: 0fr; opacity: 0; pointer-events: none;
    transition: grid-template-rows .4s var(--ease), opacity .3s;
    overflow: hidden;
  }
  .nav__links > * { min-height: 0; }
  .nav__links.is-open { grid-template-rows: 1fr; opacity: 1; pointer-events: auto; }
}

/* hero */
.hero {
  max-width: var(--maxw); margin: 0 auto;
  padding: clamp(2.5rem,6vw,5rem) clamp(1.1rem,4vw,2.5rem);
  display: grid; grid-template-columns: 1.15fr 0.85fr; gap: clamp(2rem,5vw,4rem); align-items: center;
}
.hero__title { font-size: var(--step-4); margin: 0.4rem 0 0; }
.hero__title em { font-style: normal; color: var(--coral-deep); }
.hero__lead { font-size: var(--step-1); color: var(--ink-soft); margin: 1.2rem 0 1.8rem; max-width: 34ch; }
.hero__lead strong { color: var(--ink); }
.hero__actions { display: flex; flex-wrap: wrap; gap: 0.8rem; }
.hero__art img { width: 100%; height: auto; border-radius: 1.5rem; }
@media (max-width: 820px) {
  .hero { grid-template-columns: 1fr; text-align: left; }
  .hero__art { max-width: 24rem; }
}

/* challenge */
.challenge { max-width: var(--maxw); margin: 0 auto; padding: clamp(2.5rem,5vw,4.5rem) clamp(1.1rem,4vw,2.5rem); }
.steps { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(3,1fr); gap: clamp(1rem,2.5vw,1.8rem); counter-reset: s; }
.step { position: relative; background: var(--white); border: 1px solid var(--line); border-radius: 1.4rem; padding: clamp(1.6rem,3vw,2.2rem); }
.step__num { position: absolute; top: -0.7rem; left: clamp(1.6rem,3vw,2.2rem); width: 2.2rem; height: 2.2rem; border-radius: 999px; background: var(--teal); color: var(--white); font-family: "Bricolage Grotesque",sans-serif; font-weight: 700; display: grid; place-items: center; }
.step__icon { width: 4rem; height: 4rem; object-fit: contain; margin: 0.6rem 0 1rem; }
.step h3 { font-size: var(--step-1); margin: 0 0 0.5rem; }
.step p { margin: 0; color: var(--ink-soft); }
.challenge__cta { text-align: center; margin-top: clamp(2rem,4vw,3rem); }
@media (max-width: 760px) { .steps { grid-template-columns: 1fr; } }

/* role */
.role { background: var(--cream-2); }
.role { max-width: none; }
.role { display: grid; grid-template-columns: 0.85fr 1.15fr; gap: clamp(2rem,5vw,4rem); align-items: center;
  padding: clamp(3rem,6vw,5rem) clamp(1.1rem,4vw,2.5rem); }
.role > * { max-width: calc(var(--maxw) / 2); }
.role__art { justify-self: center; }
.role__art img { width: 100%; max-width: 26rem; height: auto; }
.role__text { margin-left: auto; margin-right: auto; }
.role__text p { color: var(--ink-soft); }
.role__text p + p { margin-top: 1rem; }
@media (max-width: 820px) { .role { grid-template-columns: 1fr; } .role__art { max-width: 20rem; } }

/* facts */
.facts { max-width: var(--maxw); margin: 0 auto; padding: clamp(3rem,6vw,5rem) clamp(1.1rem,4vw,2.5rem); }
.facts__grid { display: grid; grid-template-columns: repeat(3,1fr); gap: clamp(1rem,2.5vw,1.6rem); }
.fact { background: var(--white); border: 1px solid var(--line); border-radius: 1.3rem; padding: clamp(1.4rem,2.8vw,1.9rem); transition: transform .35s var(--ease), box-shadow .35s var(--ease); }
.fact:hover { transform: translateY(-3px); box-shadow: 0 18px 38px -22px oklch(0.30 0.045 200 / 0.4); }
.fact__icon { width: 3.4rem; height: 3.4rem; object-fit: contain; margin-bottom: 0.9rem; }
.fact h3 { font-size: var(--step-1); margin: 0 0 0.5rem; }
.fact p { margin: 0; color: var(--ink-soft); font-size: var(--step-0); }
@media (max-width: 860px) { .facts__grid { grid-template-columns: repeat(2,1fr); } }
@media (max-width: 560px) { .facts__grid { grid-template-columns: 1fr; } }

/* stacks-up: quiz + video */
.stacks { background: var(--teal-deep); color: var(--cream); }
.stacks { padding: clamp(3rem,6vw,5.5rem) clamp(1.1rem,4vw,2.5rem); }
.stacks .section-title { color: var(--white); }
.stacks .eyebrow--coral { color: oklch(0.82 0.12 40); }
.stacks__sub { max-width: 42ch; margin: 0.6rem auto 0; color: oklch(0.92 0.02 120); }
.stacks__quiz { max-width: 52rem; margin: clamp(2rem,4vw,3rem) auto 0; background: var(--white); border-radius: 1.4rem; padding: 0.6rem; overflow: hidden; }
.stacks__quiz [data-tf-live] { min-height: 480px; border-radius: 1rem; overflow: hidden; }
.stacks__video { max-width: 52rem; margin: clamp(1.5rem,3vw,2.2rem) auto 0; border-radius: 1.4rem; overflow: hidden; box-shadow: 0 24px 60px -30px oklch(0 0 0 / 0.6); }

/* faq */
.faq { max-width: 50rem; margin: 0 auto; padding: clamp(3rem,6vw,5rem) clamp(1.1rem,4vw,2.5rem); }
.faq__list { display: flex; flex-direction: column; gap: 0.8rem; }
.faq__item { background: var(--white); border: 1px solid var(--line); border-radius: 1rem; padding: 0 clamp(1.1rem,2.5vw,1.6rem); }
.faq__item summary { font-family: "Bricolage Grotesque", sans-serif; font-weight: 600; font-size: var(--step-1); padding: 1.1rem 2rem 1.1rem 0; cursor: pointer; list-style: none; position: relative; }
.faq__item summary::-webkit-details-marker { display: none; }
.faq__item summary::after { content: "+"; position: absolute; right: 0; top: 50%; transform: translateY(-50%); font-size: 1.6rem; font-weight: 400; color: var(--teal-deep); transition: transform .3s var(--ease); }
.faq__item[open] summary::after { transform: translateY(-50%) rotate(45deg); }
.faq__item p { margin: 0 0 1.1rem; color: var(--ink-soft); }

/* footer */
.site-footer { background: var(--ink); color: oklch(0.92 0.02 120); padding: clamp(3rem,6vw,4.5rem) clamp(1.1rem,4vw,2.5rem); }
.site-footer__inner { max-width: 40rem; margin: 0 auto; text-align: center; display: flex; flex-direction: column; align-items: center; gap: 1.1rem; }
.site-footer__logo { height: 3.4rem; width: auto; }
.site-footer__date { font-family: "Bricolage Grotesque",sans-serif; font-size: var(--step-1); margin: 0; color: var(--cream); }
.site-footer__social { display: flex; gap: 1rem; }
.site-footer__social a { display: inline-flex; width: 2.6rem; height: 2.6rem; border-radius: 999px; background: oklch(1 0 0 / 0.1); align-items: center; justify-content: center; transition: background-color .25s; }
.site-footer__social a:hover { background: oklch(1 0 0 / 0.22); }
.site-footer__social img { width: 1.4rem; height: 1.4rem; filter: brightness(0) invert(1); }
.site-footer__media { color: var(--cream); font-weight: 600; text-underline-offset: 3px; }
.site-footer__copy { font-size: var(--step--1); color: oklch(0.78 0.02 120); margin: 0.4rem 0 0; }

/* reveal */
.reveal { opacity: 0; transform: translateY(18px); }
.reveal.is-in { opacity: 1; transform: none; transition: opacity .7s var(--ease), transform .7s var(--ease); }
@media (prefers-reduced-motion: reduce) {
  .reveal, .reveal.is-in { opacity: 1; transform: none; transition: none; }
  .btn:hover, .fact:hover { transform: none; }
}