/* ============================================================================
   layout.css — app shell, header + nav, scene frame, footer, responsive system
   ----------------------------------------------------------------------------
   Contract : docs/architecture.md §3 (DOM/markup), §8 (breakpoints, behaviours
              3,4,5,6), §9 (island clip-paths live in scenes.css)
   Visual   : docs/css-style-ruleset.md (60/20/10/10 ratio, generous whitespace)
   Order    : tokens.css → base.css → layout.css → components.css → scenes.css
   ============================================================================ */

/* ============================================== 1. document + anchor offset */
html {
  /* Behaviour 3 — anchors clear the fixed header. */
  scroll-padding-top: calc(var(--header-h) + 8px);
}

body {
  /* Behaviour 6 — no horizontal overflow at any width. */
  overflow-x: hidden;
  overflow-x: clip;
}

/* ================================================================ 2. shell == */
.app {
  position: relative;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  min-height: 100svh;
  isolation: isolate;
}

.app__main {
  position: relative;
  z-index: var(--z-fg);
  flex: 1 0 auto;
  background-color: var(--bg);
}

/* ====================================================== 3. scroll progress == */
.scroll-bar {
  position: fixed;
  inset-block-start: 0;
  inset-inline-start: 0;
  z-index: calc(var(--z-header) + 1);
  width: 100%;
  height: 3px;
  background-color: var(--c-line);
  opacity: 0.6;
  pointer-events: none;
}

/* JS writes the live value as an inline transform: scaleX(progress).
   Fallback value keeps the bar empty before the first frame. */
[data-scroll-bar-fill] {
  display: block;
  width: 100%;
  height: 100%;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background-image: linear-gradient(90deg, var(--c-rose), var(--c-rose-deep));
}

/* ================================================================ 4. header == */
/* Default state = off-canvas (the hero has no header; it appears on scroll).
   State classes toggled by MP.header.setVisible(): .is-visible / .is-hidden,
   plus .is-scrolled for the condensed treatment. */
.site-header {
  position: fixed;
  inset-block-start: 0;
  inset-inline: 0;
  z-index: var(--z-header);
  background-color: var(--c-cream);
  border-bottom: 1px solid transparent;
  transform: translateY(-100%);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition:
    transform var(--dur-mid) var(--ease-out),
    opacity var(--dur-mid) var(--ease-out),
    background-color var(--dur-mid) var(--ease-out),
    border-color var(--dur-mid) var(--ease-out),
    visibility 0s linear var(--dur-mid);
}

.site-header.is-visible {
  transform: translateY(0);
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transition-delay: 0s;
}

.site-header.is-hidden {
  transform: translateY(-100%);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

/* Condensed treatment once the page has moved (plan §9 "subtle backdrop"). */
.site-header.is-scrolled {
  background-color: color-mix(in srgb, var(--c-cream) 88%, transparent);
  -webkit-backdrop-filter: blur(10px) saturate(1.15);
  backdrop-filter: blur(10px) saturate(1.15);
  border-bottom-color: var(--c-line);
  box-shadow: var(--shadow-sm);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-4);
  width: 100%;
  max-width: var(--max-w);
  height: var(--header-h);
  margin-inline: auto;
  padding-inline: var(--scene-pad);
}

.brand {
  color: var(--text);
  font-family: var(--font-display);
  font-size: var(--fs-h3);
  line-height: 1;
  letter-spacing: 0.01em;
  white-space: nowrap;
  text-decoration: none;
}

/* ================================================================ 5. nav ==== */
.nav__list {
  display: flex;
  align-items: center;
  gap: var(--sp-1);
}

.nav__link {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: var(--sp-1) var(--sp-2);
  border-radius: var(--r-pill);
  background: none;
  color: var(--text);
  font-family: var(--font-body);
  font-size: var(--fs-sm);
  font-weight: 600;
  text-decoration: none;
  transition: color var(--dur-fast) var(--ease-out),
              background-color var(--dur-fast) var(--ease-out);
}

/* Current section — header.js adds .is-current + aria-current (never colour alone) */
.nav__link.is-current,
.nav__link[aria-current="true"],
.nav__link[aria-current="page"],
.nav__menu-link.is-current,
.nav__menu-link[aria-current="true"],
.mobile-nav__link.is-current,
.mobile-nav__link[aria-current="true"] {
  background-color: var(--surface-2);
  color: var(--accent-strong);
}

/* "My Works" dropdown */
.nav__group {
  position: relative;
}

.nav__menu {
  position: absolute;
  inset-block-start: calc(100% + var(--sp-1));
  inset-inline-start: 50%;
  z-index: var(--z-header);
  min-width: 15rem;
  max-width: min(80vw, 20rem);
  display: grid;
  gap: 2px;
  padding: var(--sp-2);
  border: 1px solid var(--c-line);
  border-radius: var(--r-md);
  background-color: var(--surface);
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translate(-50%, -6px);
  transition: opacity var(--dur-fast) var(--ease-out),
              transform var(--dur-fast) var(--ease-out),
              visibility 0s linear var(--dur-fast);
}

.nav__group.is-open .nav__menu,
.nav__group .nav__link[aria-expanded="true"] + .nav__menu {
  opacity: 1;
  visibility: visible;
  transform: translate(-50%, 0);
  transition-delay: 0s;
}

/* Transparent hover bridge across the button→panel gap (header.js opens the
   menu on the group's mouseenter, so the pointer must never leave the group). */
.nav__menu::before {
  content: "";
  position: absolute;
  inset-inline: 0;
  inset-block-start: calc(-1 * var(--sp-2));
  height: var(--sp-2);
}

/* header.js generates these links with the .nav__menu-link / .nav__menu-item classes */
.nav__menu-link {
  display: flex;
  align-items: center;
  width: 100%;
  min-height: 40px;
  padding: var(--sp-1) var(--sp-2);
  border-radius: var(--r-sm);
  color: var(--text);
  font-size: var(--fs-sm);
  font-weight: 600;
  text-decoration: none;
  transition: color var(--dur-fast) var(--ease-out),
              background-color var(--dur-fast) var(--ease-out);
}

/* Hamburger — hidden on desktop, shown ≤ 860px */
.nav-toggle {
  display: none;
  place-items: center;
  width: 44px;
  height: 44px;
  border: 1px solid var(--c-line);
  border-radius: var(--r-pill);
  background-color: var(--surface);
  color: var(--text);
  transition: background-color var(--dur-fast) var(--ease-out);
}

.nav-toggle__box {
  display: grid;
  gap: 5px;
  width: 22px;
}

.nav-toggle__box i {
  display: block;
  height: 2px;
  border-radius: var(--r-pill);
  background-color: currentColor;
  transition: transform var(--dur-fast) var(--ease-out),
              opacity var(--dur-fast) var(--ease-out);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__box i:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__box i:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__box i:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ========================================================== 6. mobile nav == */
/* Sits just under the header so the toggle stays reachable to close it.
   `[hidden]` (behaviour 7) keeps it out of the tab order while closed. */
.mobile-nav {
  position: fixed;
  inset: 0;
  z-index: calc(var(--z-header) - 1);
  display: none;
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: calc(var(--header-h) + var(--sp-4)) var(--scene-pad) var(--sp-5);
  background-color: var(--bg);
}

.mobile-nav__inner {
  width: min(100%, 30rem);
  margin-inline: auto;
}

.mobile-nav__list {
  display: flex;
  flex-direction: column;
  gap: var(--sp-1);
}

/* header.js generates this structure: __item / __group / __label / __sublist */
.mobile-nav__link {
  display: flex;
  align-items: center;
  width: 100%;
  min-height: 52px;
  padding: var(--sp-2) var(--sp-3);
  border-radius: var(--r-md);
  color: var(--text);
  font-family: var(--font-body);
  font-size: var(--fs-h3);
  font-weight: 600;
  text-decoration: none;
  transition: background-color var(--dur-fast) var(--ease-out),
              color var(--dur-fast) var(--ease-out);
}

.mobile-nav__label {
  display: block;
  padding: var(--sp-3) var(--sp-3) var(--sp-1);
  color: var(--accent-strong);
  font-size: var(--fs-label);
  font-weight: 700;
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
}

.mobile-nav__sublist {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

/* Secondary level: mauve is only legal at >= 15px (behaviour 10), and
   --fs-body bottoms out at 0.9375rem = 15px. */
.mobile-nav__sublist .mobile-nav__link {
  min-height: 44px;
  padding-inline-start: var(--sp-5);
  color: var(--text-soft);
  font-size: var(--fs-body);
}

/* Gentle entrance; base.css caps this to 1ms under reduced motion. */
@keyframes mp-mobile-nav-in {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.mobile-nav.is-open {
  animation: mp-mobile-nav-in var(--dur-mid) var(--ease-out);
}

/* =============================================================== 7. scenes == */
.scene {
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: center;
  /* Behaviour 5 — never a bare 100vh. */
  min-height: 100vh;
  min-height: 100svh;
  padding: var(--scene-pad);
  background-color: var(--bg);
  isolation: isolate;
}

/* Generic tinted background layer. scenes.css layers gradients/atmosphere on
   top; this guarantees a pastel family even with no scene CSS present. */
.scene__bg {
  position: absolute;
  inset: 0;
  z-index: var(--z-bg);
  background-color: var(--tint);
  pointer-events: none;
}

.scenes-root {
  position: relative;
  display: block;
}

/* =============================================================== 8. footer == */
.site-footer {
  position: relative;
  z-index: var(--z-fg);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-3) var(--sp-5);
  padding: var(--sp-5) var(--scene-pad);
  border-top: 1px solid var(--c-line);
  background-color: var(--bg-alt);
  color: var(--text);
  font-size: var(--fs-sm);
}

.site-footer__copy {
  max-width: 60ch;
}

.site-footer__links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2) var(--sp-4);
}

.site-footer__links a,
.site-footer__top {
  color: var(--text);
  font-size: var(--fs-sm);
  font-weight: 600;
  text-decoration: none;
}

.site-footer__top {
  padding: var(--sp-1) var(--sp-3);
  border: 1px solid var(--c-line);
  border-radius: var(--r-pill);
  background-color: var(--surface);
}

/* ========================================== 9. clip-path defs container ==== */
.svg-defs {
  position: absolute;
  width: 0;
  height: 0;
  overflow: hidden;
  pointer-events: none;
}

/* ==================================================== 10. hover (gated) ==== */
/* Behaviour 4 — desktop pointers only. */
@media (hover: hover) and (pointer: fine) {
  .brand:hover {
    color: var(--accent-strong);
  }

  .nav__link:hover {
    background-color: var(--surface-2);
    color: var(--accent-strong);
  }

  .nav__menu-link:hover,
  .mobile-nav__link:hover {
    background-color: var(--surface-2);
    color: var(--accent-strong);
  }

  .nav-toggle:hover {
    background-color: var(--surface-2);
  }

  .site-footer__links a:hover {
    color: var(--accent-strong);
    text-decoration-line: underline;
  }

  .site-footer__top:hover {
    border-color: var(--accent);
    color: var(--accent-strong);
  }
}

/* ================================================= 11. responsive system === */
/* Exact breakpoints from architecture §8. */

/* Wide desktops — let the cinematic composition breathe. */
@media (min-width: 1800px) {
  :root {
    --max-w: 1680px;
    --scene-pad: clamp(64px, 6vw, 128px);
  }
}

/* Tablet landscape — reduce scale + density, keep the composition. */
@media (max-width: 1100px) {
  :root {
    --header-h: 68px;
    --scene-pad: clamp(24px, 4.2vw, 64px);
  }
}

/* Tablet portrait — swap to the compact nav. */
@media (max-width: 860px) {
  :root {
    --header-h: 64px;
    --scene-pad: clamp(20px, 5vw, 44px);
  }

  .nav {
    display: none;
  }

  .nav-toggle {
    display: grid;
  }

  .mobile-nav {
    display: block;
  }
}

/* Mobile — vertical stack, full-width media, tight nav. */
@media (max-width: 600px) {
  :root {
    --header-h: 58px;
    --scene-pad: 20px;
    --max-w: 100%;
  }

  .site-header__inner {
    gap: var(--sp-2);
  }

  .brand {
    font-size: var(--fs-body);
  }

  .site-footer {
    flex-direction: column;
    align-items: flex-start;
  }

  .mobile-nav__inner {
    width: 100%;
  }
}

/* Short viewports (e.g. 1280x560) — top-align scenes so nothing is unreachable. */
@media (max-height: 620px) {
  :root {
    --header-h: 56px;
    --scene-pad: 20px;
  }

  .scene {
    justify-content: flex-start;
    padding-block: calc(var(--header-h) + var(--sp-4)) var(--sp-5);
  }
}