/* Simple Heart Rate Monitor - support site
   No webfonts, no scripts, no third-party requests. The privacy policy
   hosted here says the product contacts nobody; the site holds to that. */

:root {
  --ink:        #10151c;
  --panel:      #171e27;
  --panel-2:    #1d2531;
  --rule:       #263140;
  --rule-soft:  #1f2833;
  --text:       #dde3ea;
  --text-dim:   #97a5b6;
  --text-faint: #6b7a8c;

  /* The five training zones are the app's only chromatic vocabulary,
     so they are this page's palette too. */
  --z1: #3b82a0;
  --z2: #3f9c6b;
  --z3: #c9a227;
  --z4: #e0651f;
  --z5: #c8384a;

  --mono: ui-monospace, "SF Mono", SFMono-Regular, Menlo, Consolas,
          "Liberation Mono", "Courier New", monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
          "Helvetica Neue", Arial, sans-serif;

  --col: 40rem;
}

@media (prefers-color-scheme: light) {
  :root {
    --ink:        #f2f4f7;
    --panel:      #ffffff;
    --panel-2:    #e9edf2;
    --rule:       #ccd4de;
    --rule-soft:  #dde3ea;
    --text:       #131a22;
    --text-dim:   #4d5b6b;
    --text-faint: #74828f;
    --z1: #2c6a86;
    --z2: #2f7d53;
    --z3: #94750f;
    --z4: #b64d10;
    --z5: #a82333;
  }
}

*, *::before, *::after { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--ink);
  color: var(--text);
  font-family: var(--sans);
  font-size: 1rem;
  line-height: 1.65;
  padding: 0 1.5rem 6rem;
}

/* ---------- masthead ---------- */

.bar {
  max-width: var(--col);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
  padding: 1.25rem 0;
  border-bottom: 1px solid var(--rule);
  font-family: var(--mono);
  font-size: 0.75rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.bar b { font-weight: 600; color: var(--text); }
.bar a { color: var(--text-dim); text-decoration: none; border-bottom: 1px solid transparent; }
.bar a:hover, .bar a:focus-visible { color: var(--text); border-bottom-color: var(--z1); }

/* ---------- layout ---------- */

main { max-width: var(--col); margin: 0 auto; }

.hero { padding: 3.5rem 0 2.5rem; }

.eyebrow {
  font-family: var(--mono);
  font-size: 0.7rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--text-faint);
  margin: 0 0 1.25rem;
}

h1 {
  font-family: var(--mono);
  font-weight: 600;
  font-size: clamp(1.75rem, 7vw, 2.6rem);
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin: 0;
}

h1 span { display: block; color: var(--text-faint); }

.lede {
  margin: 1.5rem 0 0;
  font-size: 1.0625rem;
  color: var(--text-dim);
  max-width: 34rem;
}

section { padding: 2.75rem 0 0; }

h2 {
  font-family: var(--mono);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--text-faint);
  margin: 0 0 1.5rem;
  padding-bottom: 0.6rem;
  border-bottom: 1px solid var(--rule);
}

h3 {
  font-family: var(--sans);
  font-size: 1rem;
  font-weight: 600;
  margin: 2rem 0 0.5rem;
}

p { margin: 0 0 1rem; }
p:last-child { margin-bottom: 0; }

a { color: var(--text); text-decoration: underline; text-decoration-color: var(--z1); text-underline-offset: 0.2em; }
a:hover, a:focus-visible { text-decoration-color: var(--text); }

code {
  font-family: var(--mono);
  font-size: 0.875em;
  background: var(--panel-2);
  padding: 0.1em 0.35em;
  border-radius: 2px;
}

strong { font-weight: 600; }

/* ---------- status panels: the signature element ---------- */

.panel {
  background: var(--panel);
  border: 1px solid var(--rule);
  border-left: 3px solid var(--z2);
  padding: 1.25rem 1.375rem;
  margin: 1.25rem 0 0;
}

.panel-head {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--mono);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--z2);
  margin: 0 0 0.75rem;
}

.led {
  width: 0.5rem;
  height: 0.5rem;
  border-radius: 50%;
  background: var(--z2);
  flex: none;
}

.panel p { color: var(--text-dim); font-size: 0.9375rem; }

.panel--alert { border-left-color: var(--z5); }
.panel--alert .panel-head { color: var(--z5); font-size: 0.9375rem; letter-spacing: 0.1em; }
.panel--alert .led { background: var(--z5); animation: pulse 1.8s ease-in-out infinite; }
.panel--alert strong { color: var(--text); }

@keyframes pulse { 0%, 100% { opacity: 1; } 50% { opacity: 0.3; } }

@media (prefers-reduced-motion: reduce) {
  .panel--alert .led { animation: none; }
}

/* ---------- compatibility split ---------- */

.split {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
}

@media (min-width: 40rem) {
  .split { grid-template-columns: 1fr 1fr; gap: 2.5rem; }
}

.split h3 {
  margin: 0 0 0.875rem;
  font-family: var(--mono);
  font-size: 0.7rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--rule-soft);
}

.split-yes h3 { color: var(--z2); }
.split-no  h3 { color: var(--z5); }

.split ul { list-style: none; margin: 0; padding: 0; }
.split li {
  font-size: 0.9375rem;
  color: var(--text-dim);
  padding: 0.3rem 0 0.3rem 1.1rem;
  position: relative;
}
.split li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.95em;
  width: 0.45rem;
  height: 1px;
  background: currentColor;
  opacity: 0.6;
}
.split li b { color: var(--text); font-weight: 600; }
.split-note { font-size: 0.875rem; color: var(--text-faint); margin-top: 1rem; }

/* ---------- question list ---------- */

.qa { border-top: 1px solid var(--rule-soft); }

.qa > div {
  border-bottom: 1px solid var(--rule-soft);
  padding: 1.375rem 0;
}

.q {
  font-weight: 600;
  font-size: 1rem;
  margin: 0 0 0.5rem;
  color: var(--text);
}

.qa p { color: var(--text-dim); font-size: 0.9375rem; }

/* ---------- ordered steps ---------- */

ol.steps {
  margin: 0.5rem 0 0;
  padding-left: 0;
  list-style: none;
  counter-reset: step;
}

ol.steps li {
  counter-increment: step;
  position: relative;
  padding: 0 0 0.75rem 2.25rem;
  font-size: 0.9375rem;
  color: var(--text-dim);
}

ol.steps li::before {
  content: counter(step, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 0;
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--z1);
  letter-spacing: 0.05em;
}

ol.steps li b { color: var(--text); font-weight: 600; }

/* ---------- zone ramp ---------- */

.ramp { display: flex; height: 3px; margin: 3rem 0 0; }
.ramp i { flex: 1; }
.ramp i:nth-child(1) { background: var(--z1); }
.ramp i:nth-child(2) { background: var(--z2); }
.ramp i:nth-child(3) { background: var(--z3); }
.ramp i:nth-child(4) { background: var(--z4); }
.ramp i:nth-child(5) { background: var(--z5); }

/* ---------- contact + footer ---------- */

.contact {
  background: var(--panel);
  border: 1px solid var(--rule);
  padding: 1.5rem;
  margin-top: 0.5rem;
}

.contact .addr {
  font-family: var(--mono);
  font-size: 1.0625rem;
  word-break: break-all;
}

footer {
  max-width: var(--col);
  margin: 4rem auto 0;
  padding-top: 1.5rem;
  border-top: 1px solid var(--rule);
  font-size: 0.8125rem;
  color: var(--text-faint);
}

footer p { margin: 0 0 0.5rem; }

footer .meta {
  font-family: var(--mono);
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

:focus-visible {
  outline: 2px solid var(--z1);
  outline-offset: 3px;
}