/* ==========================================================================
   Virtuant AI — shell
   Navigation, footer, buttons, form controls. Shared by every page.
   ========================================================================== */

/* ---------------------------------------------------------- scroll rail -- */

.progress-rail {
  position: fixed;
  inset: 0 0 auto 0;
  height: 2px;
  z-index: 90;
  pointer-events: none;
}

.progress-rail i {
  display: block;
  height: 100%;
  width: 100%;
  background: var(--spectrum);
  transform: scaleX(var(--progress, 0));
  transform-origin: 0 50%;
}

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

.masthead {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 80;
  padding: clamp(.85rem, 1.6vw, 1.4rem) var(--gutter);
  transition: padding var(--d-mid) var(--e-out), background var(--d-mid) linear;
}

.masthead::before {
  content: "";
  position: absolute;
  inset: 0;
  background: rgba(4, 7, 15, .72);
  backdrop-filter: blur(20px) saturate(140%);
  -webkit-backdrop-filter: blur(20px) saturate(140%);
  border-bottom: 1px solid var(--line);
  opacity: 0;
  transition: opacity var(--d-mid) var(--e-out);
}

.masthead.is-stuck { padding-block: .7rem; }
.masthead.is-stuck::before { opacity: 1; }

.masthead__inner {
  position: relative;
  max-width: var(--shell);
  margin-inline: auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
}

.brand {
  display: block;
  flex: none;
  line-height: 0;
  transition: transform var(--d-fast) var(--e-out), filter var(--d-mid) var(--e-out);
}

.brand img {
  height: clamp(30px, 3.4vw, 38px);
  width: auto;
  filter: drop-shadow(0 0 22px rgba(59, 116, 255, .35));
}

.masthead.is-stuck .brand img { height: clamp(26px, 2.8vw, 31px); }
.brand:hover { transform: translateY(-1px); filter: brightness(1.08); }

/* Desktop navigation ------------------------------------------------------ */

.nav {
  display: flex;
  align-items: center;
  gap: clamp(.25rem, 1.6vw, 1.75rem);
}

.nav__link {
  position: relative;
  padding: .55rem .25rem;
  font-size: var(--t-sm);
  font-weight: 460;
  color: var(--paper-dim);
  overflow: hidden;
  transition: color var(--d-fast) var(--e-out);
}

/* Hover microinteraction: the label rolls up, its twin rolls in behind it.
   The twin is a real, aria-hidden element so the link keeps one accessible name. */
.nav__link {
  display: grid;
  grid-template-areas: "label";
}

.nav__link span {
  grid-area: label;
  transition: transform .42s var(--e-out), opacity .28s linear;
}

.nav__link span + span { transform: translateY(90%); opacity: 0; }

.nav__link:hover { color: var(--paper); }
.nav__link:hover span { transform: translateY(-90%); opacity: 0; }
.nav__link:hover span + span { transform: none; opacity: 1; }

.nav__link[aria-current="page"] { color: var(--paper); }

.nav__link[aria-current="page"]::before {
  content: "";
  position: absolute;
  left: 50%;
  bottom: -2px;
  width: 4px;
  height: 4px;
  margin-left: -2px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 10px var(--cyan);
}

.nav__cta { margin-left: clamp(.5rem, 1.5vw, 1rem); }

/* Mobile trigger ---------------------------------------------------------- */

.nav-toggle {
  display: none;
  position: relative;
  z-index: 2;
  width: 46px;
  height: 46px;
  margin-right: -6px;
  border: 1px solid var(--line-strong);
  border-radius: var(--r-sm);
  background: var(--fill);
  transition: border-color var(--d-fast) linear, background var(--d-fast) linear;
}

.nav-toggle:hover { border-color: rgba(146, 172, 255, .45); }

.nav-toggle i {
  position: absolute;
  left: 13px;
  width: 18px;
  height: 2px;
  background: var(--paper);
  border-radius: 2px;
  transition: transform .4s var(--e-out), width .4s var(--e-out);
}

.nav-toggle i:nth-child(1) { top: 19px; }
.nav-toggle i:nth-child(2) { top: 26px; width: 11px; }

.nav-open .nav-toggle i:nth-child(1) { transform: translateY(3.5px) rotate(45deg); }
.nav-open .nav-toggle i:nth-child(2) { transform: translateY(-3.5px) rotate(-45deg); width: 18px; }

/* Mobile sheet ------------------------------------------------------------ */

.nav-sheet {
  position: fixed;
  inset: 0;
  z-index: 79;
  display: grid;
  align-content: center;
  padding: 6rem var(--gutter) 3rem;
  background: var(--ink-950);
  clip-path: inset(0 0 100% 0);
  transition: clip-path .72s var(--e-inout);
  visibility: hidden;
}

.nav-sheet::after {
  content: "";
  position: absolute;
  inset: auto -20% -30% -20%;
  height: 60%;
  background: radial-gradient(60% 100% at 50% 100%, rgba(59, 116, 255, .22), transparent 70%);
  pointer-events: none;
}

.nav-open .nav-sheet {
  clip-path: inset(0 0 0 0);
  visibility: visible;
}

.nav-sheet__list { display: grid; gap: .25rem; }

.nav-sheet__list a {
  position: relative;
  display: flex;
  align-items: baseline;
  gap: 1rem;
  padding: .5rem 0;
  font-family: var(--f-display);
  font-size: clamp(2rem, 11vw, 3.4rem);
  font-weight: 600;
  letter-spacing: -0.04em;
  border-bottom: 1px solid var(--line);
  opacity: 0;
  transform: translateY(24px);
  transition: opacity .5s var(--e-out), transform .6s var(--e-out);
}

.nav-open .nav-sheet__list a {
  opacity: 1;
  transform: none;
  transition-delay: calc(.16s + var(--i) * .06s);
}

.nav-sheet__list a[aria-current="page"] { color: var(--cyan); }

.nav-sheet__list em {
  font-family: var(--f-body);
  font-style: normal;
  font-size: .75rem;
  letter-spacing: .16em;
  color: var(--paper-faint);
}

.nav-sheet__foot {
  margin-top: 3rem;
  display: grid;
  gap: .4rem;
  font-size: var(--t-sm);
  color: var(--paper-dim);
  opacity: 0;
  transition: opacity .5s var(--e-out) .42s;
}

.nav-open .nav-sheet__foot { opacity: 1; }

@media (max-width: 860px) {
  .nav { display: none; }
  .nav-toggle { display: block; }
}

/* -------------------------------------------------------------- buttons -- */

.btn {
  --btn-bg: transparent;
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .7rem;
  padding: .95rem 1.6rem;
  border-radius: var(--r-sm);
  background: var(--btn-bg);
  font-size: var(--t-sm);
  font-weight: 520;
  letter-spacing: -0.01em;
  white-space: nowrap;
  isolation: isolate;
  transition: transform var(--d-fast) var(--e-out), color var(--d-fast) linear,
              border-color var(--d-fast) linear, box-shadow var(--d-mid) var(--e-out);
}

.btn svg {
  width: 15px;
  height: 15px;
  flex: none;
  transition: transform .38s var(--e-out);
}

.btn:hover svg { transform: translateX(4px); }

/* Primary — the brand spectrum, the only place it appears as a solid fill */
.btn--primary {
  color: var(--ink-950);
  font-weight: 600;
  background: var(--spectrum);
  background-size: 220% 100%;
  background-position: 0% 50%;
  transition: background-position .7s var(--e-out), transform var(--d-fast) var(--e-out),
              box-shadow var(--d-mid) var(--e-out);
}

.btn--primary:hover {
  background-position: 100% 50%;
  box-shadow: 0 14px 44px -14px rgba(59, 116, 255, .8);
}

/* Ghost — hairline that fills from the pointer's side on hover */
.btn--ghost {
  color: var(--paper);
  border: 1px solid var(--line-strong);
}

.btn--ghost::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  border-radius: inherit;
  background: var(--fill-strong);
  opacity: 0;
  transition: opacity var(--d-fast) linear;
}

.btn--ghost:hover { border-color: rgba(146, 172, 255, .5); }
.btn--ghost:hover::before { opacity: 1; }

/* Quiet — text with a rule that draws in */
.btn--quiet {
  padding-inline: 0;
  color: var(--paper);
  border-radius: 0;
}

.btn--quiet::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: .55rem;
  height: 1px;
  width: 100%;
  background: var(--spectrum);
  transform: scaleX(0);
  transform-origin: 0 50%;
  transition: transform .5s var(--e-out);
}

.btn--quiet:hover::after { transform: scaleX(1); }

.btn--lg { padding: 1.15rem 2.1rem; font-size: var(--t-md); }

.btn:active { transform: scale(.98); }

/* ---------------------------------------------------------------- forms -- */

.form { display: grid; gap: 1.6rem; }

.form__row {
  display: grid;
  gap: 1.6rem;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
}

.field { position: relative; }

.field__input {
  width: 100%;
  padding: 1.7rem 0 .8rem;
  font-size: var(--t-md);
  color: var(--paper);
  border-bottom: 1px solid var(--line-strong);
  border-radius: 0;
  transition: border-color var(--d-fast) linear;
}

textarea.field__input { resize: vertical; min-height: 7rem; line-height: 1.6; }

select.field__input {
  appearance: none;
  cursor: pointer;
  background-image: linear-gradient(45deg, transparent 50%, var(--paper-dim) 50%),
                    linear-gradient(135deg, var(--paper-dim) 50%, transparent 50%);
  background-position: right 8px center, right 3px center;
  background-size: 5px 5px, 5px 5px;
  background-repeat: no-repeat;
}

select.field__input option { background: var(--ink-800); color: var(--paper); }

.field__label {
  position: absolute;
  left: 0;
  top: 1.6rem;
  font-size: var(--t-md);
  color: var(--paper-faint);
  pointer-events: none;
  transform-origin: 0 50%;
  transition: transform .42s var(--e-out), color var(--d-fast) linear;
}

/* Gradient underline that draws from the left on focus */
.field::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  height: 1px;
  width: 100%;
  background: var(--spectrum);
  transform: scaleX(0);
  transform-origin: 0 50%;
  transition: transform .55s var(--e-out);
}

.field:focus-within::after { transform: scaleX(1); }

/* The label lifts once the control holds a value — or always, for the
   date/time controls that render their own placeholder text. */
.field:focus-within .field__label,
input.field__input:not(:placeholder-shown) + .field__label,
textarea.field__input:not(:placeholder-shown) + .field__label,
select.field__input:valid + .field__label,
input[type="date"] + .field__label,
input[type="time"] + .field__label {
  transform: translateY(-1.55rem) scale(.72);
  color: var(--paper-dim);
}

input[type="date"].field__input,
input[type="time"].field__input { color-scheme: dark; }

.field__input:focus-visible { outline: none; }

.field.is-invalid .field__input { border-bottom-color: #ff6b8a; }
.field.is-invalid .field__label { color: #ff6b8a; }

.field__error {
  display: block;
  min-height: 1.1rem;
  padding-top: .4rem;
  font-size: var(--t-xs);
  color: #ff6b8a;
  opacity: 0;
  transform: translateY(-3px);
  transition: opacity var(--d-fast) linear, transform var(--d-fast) var(--e-out);
}

.field.is-invalid .field__error { opacity: 1; transform: none; }

/* Submitted state ---------------------------------------------------------- */

.form-status {
  display: grid;
  gap: .75rem;
  padding: 2.5rem 0;
}

.form-status svg { width: 40px; height: 40px; color: var(--cyan); }

/* --------------------------------------------------------------- footer -- */

.footer {
  position: relative;
  padding: clamp(4rem, 8vw, 7rem) 0 2.5rem;
  border-top: 1px solid var(--line);
  background: var(--ink-950);
}

.footer::before {
  content: "";
  position: absolute;
  inset: -1px 0 auto 0;
  height: 1px;
  background: var(--spectrum);
  opacity: .5;
  mask-image: linear-gradient(90deg, transparent, #000 30%, #000 70%, transparent);
}

.footer__grid {
  display: grid;
  gap: clamp(2.5rem, 5vw, 4rem);
  grid-template-columns: minmax(260px, 1.4fr) repeat(2, minmax(150px, .8fr));
  align-items: start;
}

.footer__brand img {
  height: 40px;
  width: auto;
  margin-bottom: 1.4rem;
}

.footer__brand p {
  max-width: 34ch;
  font-size: var(--t-sm);
  color: var(--paper-dim);
}

.footer h4 {
  margin-bottom: 1.1rem;
  font-size: var(--t-xs);
  font-weight: 500;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--paper-faint);
}

.footer__links { display: grid; gap: .7rem; font-size: var(--t-sm); }

.footer__links a {
  position: relative;
  width: fit-content;
  color: var(--paper-dim);
  transition: color var(--d-fast) linear;
}

.footer__links a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -2px;
  width: 100%;
  height: 1px;
  background: currentColor;
  transform: scaleX(0);
  transform-origin: 0 50%;
  transition: transform .45s var(--e-out);
}

.footer__links a:hover { color: var(--paper); }
.footer__links a:hover::after { transform: scaleX(1); }

.footer__base {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 1rem;
  margin-top: clamp(3rem, 6vw, 5rem);
  padding-top: 1.75rem;
  border-top: 1px solid var(--line);
  font-size: var(--t-xs);
  color: var(--paper-faint);
}

@media (max-width: 720px) {
  .footer__grid { grid-template-columns: 1fr 1fr; }
  .footer__brand { grid-column: 1 / -1; }
}

/* ------------------------------------------------- pointer illumination -- */

/* A single low-cost light that follows the pointer across a dark surface. */
.lit { position: relative; isolation: isolate; }

.lit::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: radial-gradient(420px circle at var(--px) var(--py),
              rgba(59, 116, 255, .13), transparent 62%);
  opacity: 0;
  transition: opacity .55s var(--e-out);
  pointer-events: none;
}

.lit:hover::before { opacity: 1; }

@media (hover: none) {
  .lit::before { display: none; }
}