/* ============================================================
   COMPONENTS: buttons, masthead, folio, chapter index
   ============================================================ */

/* ──────────────── BUTTONS ────────────────
   One shape, one label per intent ("Book a call"). A split button: the
   label, a hairline, and an arrow cell. The fill swaps with the ground
   so the label always sits on the colour it contrasts with. */
.btn {
  --pad-y: 0.95rem;
  --pad-x: 1.25rem;
  --rule: rgb(255 255 255 / 0.32);
  display: inline-flex;
  align-items: stretch;
  border-radius: var(--radius);
  font-family: var(--f-text);
  font-size: 1rem;
  font-weight: 500;
  letter-spacing: -0.005em;
  line-height: 1;
  white-space: nowrap;
  cursor: pointer;
  transition:
    transform var(--d-fast) var(--e-out),
    background-color var(--d-fast) var(--e-out),
    box-shadow var(--d-base) var(--e-out);
}
.btn__label {
  display: inline-flex;
  align-items: center;
  padding: var(--pad-y) var(--pad-x);
  transition: transform var(--d-base) var(--e-out);
}
.btn__arr {
  display: inline-grid;
  place-items: center;
  width: 3.1em;
  border-left: 1px solid var(--rule);
  overflow: hidden;
}
.btn__arr svg {
  width: 1.05em;
  height: auto;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.5;
  stroke-linecap: round;
  stroke-linejoin: round;
  transition: transform var(--d-base) var(--e-out);
}
.btn:active { transform: scale(0.97); }

/* on white: ink fill, white label (5.14:1) */
.btn--primary {
  background: var(--orange-ink);
  color: var(--white);
}
/* on orange: white fill, ink label (5.14:1) */
[data-ground="orange"] .btn--primary {
  --rule: rgb(204 53 16 / 0.22);
  background: var(--white);
  color: var(--orange-ink);
}

@media (hover: hover) and (pointer: fine) {
  .btn--primary:hover { background: var(--orange-press); }
  [data-ground="orange"] .btn--primary:hover { background: var(--white); box-shadow: var(--e1); transform: translateY(-1px); }
  .btn:hover .btn__label { transform: translateX(-2px); }
  .btn:hover .btn__arr svg { transform: translateX(3px); }
}

.btn--sm { --pad-y: 0.72rem; --pad-x: 1rem; font-size: 0.9375rem; }

/* ──────────────── MASTHEAD (title page only, not fixed) ──────────────── */
.mast {
  position: relative;
  z-index: 4;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--s-3);
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding: clamp(1.1rem, 2.4vw, 1.8rem) var(--gut) 0;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.8rem;
  flex: none;
}
.brand__mark {
  width: 44px;
  color: currentColor;
  overflow: visible;
}
.brand__mark path {
  stroke-dasharray: 100;
  stroke-dashoffset: 0;
  transition: stroke-dashoffset 900ms var(--e-out);
}
.brand__mark path:last-child { transition-delay: 70ms; }
@media (hover: hover) and (pointer: fine) {
  .brand:hover .brand__mark path { stroke-dashoffset: 200; }
}
.brand__text {
  display: grid;
  gap: 0.3rem;
  line-height: 1.1;
}
/* The name is the logotype (WCAG 1.4.3 exempts it); the role line
   under it is text, so it stays at the 19px bold floor. */
.brand__name {
  font-family: var(--f-display);
  font-size: 1.125rem;
  font-weight: 500;
  letter-spacing: -0.03em;
}
.brand__role {
  font-family: var(--f-mono);
  font-size: var(--t-o-label);
  font-weight: 700;
  letter-spacing: -0.02em;
}

.mast__links {
  display: flex;
  align-items: center;
  gap: clamp(1rem, 2.2vw, 2.25rem);
  font-family: var(--f-mono);
  font-size: var(--t-o-label);
  font-weight: 700;
  letter-spacing: -0.02em;
}
.mast__links a { position: relative; padding-block: 0.2rem; }
.mast__links a::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: 0;
  height: 1.5px;
  background: currentColor;
  transform: scaleX(0);
  transform-origin: right;
  transition: transform var(--d-slow) var(--e-out);
}
@media (hover: hover) and (pointer: fine) {
  .mast__links a:hover::after { transform: scaleX(1); transform-origin: left; }
}

@media (max-width: 1060px) {
  .mast__links { display: none; }
}
@media (max-width: 560px) {
  .brand__role { display: none; }
  .brand__mark { width: 38px; }
}
@media (max-width: 400px) {
  .brand { gap: 0.55rem; }
  .brand__mark { width: 30px; }
  .brand__name { font-size: 0.95rem; }
  .mast .btn--sm { --pad-x: 0.8rem; font-size: 0.875rem; }
}

/* ──────────────── FOLIO ────────────────
   The chaptered-editorial navigation: a folio in the margin that names
   the chapter you are in and opens an index. White chips with ink text,
   so it reads identically over either ground. */
.folio { display: none; }

.js .folio {
  position: fixed;
  left: 0; right: 0;
  bottom: max(1rem, env(safe-area-inset-bottom));
  z-index: 90;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--s-2);
  padding-inline: var(--gut);
  pointer-events: none;
  opacity: 0;
  transform: translateY(12px);
  transition: opacity var(--d-base) var(--e-out), transform var(--d-slow) var(--e-out);
}
.js .folio.is-on { opacity: 1; transform: none; }
.js .folio.is-on > * { pointer-events: auto; }

.chip {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  min-height: 46px;
  padding: 0.7rem 1.05rem;
  border-radius: var(--radius);
  background: var(--white);
  color: var(--orange-ink);
  border: 1px solid rgb(204 53 16 / 0.2);
  box-shadow: var(--e1);
  font-size: 0.9375rem;
  font-weight: 500;
  letter-spacing: -0.01em;
  line-height: 1;
  transition: transform var(--d-fast) var(--e-out), box-shadow var(--d-base) var(--e-out), background-color var(--d-fast) var(--e-out);
}
.chip:active { transform: scale(0.97); }
/* A double ring: ink shows on white grounds, the white halo on orange. */
.chip:focus-visible,
.index a:focus-visible {
  outline: 2px solid var(--orange-ink);
  outline-offset: 2px;
  box-shadow: 0 0 0 6px var(--white), var(--e1);
}
@media (hover: hover) and (pointer: fine) {
  .chip:hover { box-shadow: var(--e2); transform: translateY(-1px); }
}

.chip__num {
  font-family: var(--f-mono);
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  line-height: 1;
  min-width: 2.6ch;
}
.chip__title { min-width: 5.5ch; }
.chip__caret {
  width: 9px; height: 9px;
  border-right: 1.5px solid currentColor;
  border-bottom: 1.5px solid currentColor;
  transform: translateY(2px) rotate(-135deg);
  transition: transform var(--d-base) var(--e-out);
}
.chip[aria-expanded="true"] .chip__caret { transform: translateY(-2px) rotate(45deg); }

.chip--cta {
  background: var(--orange-ink);
  color: var(--white);
  border-color: var(--orange-ink);
}
@media (hover: hover) and (pointer: fine) {
  .chip--cta:hover { background: var(--orange-press); }
}

/* ──────────────── CHAPTER INDEX ──────────────── */
.index {
  position: fixed;
  left: var(--gut);
  bottom: calc(max(1rem, env(safe-area-inset-bottom)) + 58px);
  z-index: 95;
  width: min(360px, calc(100vw - 2 * var(--gut)));
  padding: 0.6rem 0;
  background: var(--white);
  color: var(--orange-ink);
  border: 1px solid rgb(204 53 16 / 0.2);
  border-radius: var(--radius);
  box-shadow: var(--e2);
  opacity: 0;
  transform: translateY(10px) scale(0.98);
  transform-origin: bottom left;
  transition: opacity var(--d-fast) var(--e-out), transform var(--d-base) var(--e-out);
}
.index.is-open { opacity: 1; transform: none; }
.index[hidden] { display: none; }

.index a {
  display: grid;
  grid-template-columns: 2.6ch 1fr;
  align-items: baseline;
  gap: 0.9rem;
  padding: 0.7rem 1.25rem;
  font-family: var(--f-display);
  font-size: 1.05rem;
  font-weight: 400;
  line-height: 1.15;
  letter-spacing: -0.03em;
  border-radius: var(--radius);
  transition: background-color var(--d-fast) var(--e-out);
}
.index a span {
  font-family: var(--f-mono);
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  text-align: right;
}
.index a[aria-current="true"] { background: rgb(255 77 46 / 0.08); }
@media (hover: hover) and (pointer: fine) {
  .index a:hover { background: rgb(255 77 46 / 0.08); }
}

@media (max-width: 640px) {
  .js .folio { bottom: max(0.75rem, env(safe-area-inset-bottom)); }
  .chip { min-height: 48px; }
  .index {
    left: var(--gut);
    right: var(--gut);
    width: auto;
  }
}