/* ============================================================
   Base — utilities, typography, topbar, buttons, footer
   ============================================================ */

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

html,
body {
  background:
    radial-gradient(circle at 70% 8%, color-mix(in srgb, var(--gac-lime) 9%, transparent), transparent 32%),
    radial-gradient(circle at 18% 32%, color-mix(in srgb, var(--gac-lime) 5%, transparent), transparent 30%),
    var(--gac-page-bg);
}

body {
  margin: 0;
  min-width: 320px;
  color: var(--gac-text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.55;
  letter-spacing: 0;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: inherit;
  text-decoration: none;
}

[hidden] {
  display: none !important; /* HTML semantics requires this — only allowed exception */
}

button,
input,
select,
textarea {
  font: inherit;
}

img {
  max-width: 100%;
  display: block;
}

/* Headings — sans by default, serif italic only inside <em> within hero/section headings */
h1, h2, h3, h4 {
  font-family: var(--font-body);
  letter-spacing: 0;
  margin: 0;
}

code,
kbd,
samp {
  font-family: var(--font-mono);
}

/* Topbar — sticky, glass card lifted off body bg */
.topbar {
  position: sticky;
  top: 10px;
  z-index: 30;
  width: min(var(--gac-topbar), calc(100% - 24px));
  margin-inline: auto;
  display: grid;
  grid-template-columns: auto minmax(220px, 1fr) auto;
  align-items: center;
  gap: 22px;
  min-height: 64px;
  padding: 0 26px;
  isolation: isolate;
  overflow: hidden;
  border: 1px solid color-mix(in srgb, var(--gac-text) 16%, transparent);
  border-radius: 12px;
  background:
    radial-gradient(circle at 8% 0%, color-mix(in srgb, white 16%, transparent), transparent 34%),
    radial-gradient(circle at 92% 0%, color-mix(in srgb, var(--gac-lime) 12%, transparent), transparent 34%),
    linear-gradient(180deg, rgba(255, 255, 255, 0.11), rgba(255, 255, 255, 0.026) 58%, rgba(255, 255, 255, 0.055)),
    rgba(10, 12, 11, 0.62);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.26),
    inset 0 -1px 0 rgba(255, 255, 255, 0.08),
    0 18px 48px color-mix(in srgb, var(--gac-glass-shadow) 82%, transparent),
    0 0 34px color-mix(in srgb, var(--gac-lime) 6%, transparent);
  backdrop-filter: blur(28px) saturate(1.35);
  -webkit-backdrop-filter: blur(28px) saturate(1.35);
}

:root[data-theme="light"] .topbar {
  border-color: color-mix(in srgb, var(--gac-text) 12%, transparent);
  background:
    radial-gradient(circle at 8% 0%, rgba(255, 255, 255, 0.92), transparent 36%),
    radial-gradient(circle at 92% 0%, color-mix(in srgb, var(--gac-lime) 12%, transparent), transparent 34%),
    linear-gradient(180deg, rgba(255, 255, 255, 0.88), rgba(247, 250, 242, 0.54) 58%, rgba(255, 255, 255, 0.64)),
    rgba(255, 255, 255, 0.62);
}

.topbar::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  border-radius: inherit;
  padding: 1px;
  background:
    linear-gradient(115deg, rgba(255, 255, 255, 0.66), transparent 24% 74%, rgba(255, 255, 255, 0.30)),
    linear-gradient(180deg, rgba(255, 255, 255, 0.26), transparent 52%, rgba(200, 255, 58, 0.14));
  -webkit-mask:
    linear-gradient(#fff 0 0) content-box,
    linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
          mask-composite: exclude;
  pointer-events: none;
}

.topbar::after {
  content: "";
  position: absolute;
  inset: 1px;
  z-index: -1;
  border-radius: 11px;
  pointer-events: none;
  background:
    linear-gradient(100deg, transparent 0 16%, rgba(255, 255, 255, 0.10) 32%, transparent 50%),
    radial-gradient(ellipse at 74% 0%, color-mix(in srgb, var(--gac-lime) 10%, transparent), transparent 56%);
  opacity: 0.92;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--gac-text);
  font-size: 14px;
  font-weight: 800;
  white-space: nowrap;
}

.brand-mark {
  width: 34px;
  height: 34px;
  display: grid;
  place-items: center;
  border-radius: 8px;
  background:
    radial-gradient(circle at 36% 18%, color-mix(in srgb, white 28%, transparent), transparent 42%),
    color-mix(in srgb, var(--gac-lime) 15%, transparent);
  border: 1px solid color-mix(in srgb, var(--gac-lime) 36%, var(--gac-glass-border));
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.18),
    0 0 22px color-mix(in srgb, var(--gac-lime) 14%, transparent);
}

.brand-mark img {
  width: 30px;
  transform: translateY(1px);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 34px;
  color: var(--nav-text);
  font-size: 13px;
  font-weight: 600;
}

.nav a {
  position: relative;
  padding-block: 4px;
  transition: color 200ms ease;
}

.nav a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -2px;
  height: 1px;
  background: var(--gac-lime);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 220ms cubic-bezier(0.2, 0.7, 0.3, 1);
}

.nav a:hover {
  color: var(--gac-text);
}

.nav a:hover::after {
  transform: scaleX(1);
}

.nav-actions {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 11px;
}

.ghost {
  color: var(--nav-text);
  font-size: 13px;
  font-weight: 700;
  padding-inline: 8px;
  transition: color 200ms ease;
}

.ghost:hover {
  color: var(--gac-text);
}

/* Buttons */
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 0 20px;
  border: 0;
  border-radius: 8px;
  background: var(--gac-lime);
  color: var(--gac-lime-ink);
  font-family: var(--font-body);
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.01em;
  cursor: pointer;
  box-shadow:
    0 14px 32px color-mix(in srgb, var(--gac-lime) 24%, transparent),
    inset 0 -1px 0 rgba(0, 0, 0, 0.18),
    inset 0 1px 0 color-mix(in srgb, white 30%, transparent);
  transition: transform 180ms ease-out, box-shadow 220ms ease-out, background 200ms ease-out;
}

.button:hover {
  background: var(--gac-lime-hot);
  transform: translateY(-1px);
}

.button.small {
  min-width: 130px;
  min-height: 40px;
  padding: 0 18px;
  font-size: 12px;
  white-space: nowrap;
}

.topbar .button.small {
  border: 1px solid color-mix(in srgb, white 28%, transparent);
  background:
    radial-gradient(circle at 28% 0%, color-mix(in srgb, white 34%, transparent), transparent 44%),
    linear-gradient(180deg, var(--gac-lime-hot), var(--gac-lime));
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.34),
    0 12px 32px color-mix(in srgb, var(--gac-lime) 28%, transparent);
}

.button svg,
.nav-cta svg {
  width: 16px;
  height: 16px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.button.secondary {
  background: transparent;
  color: var(--gac-text);
  border: 1px solid var(--gac-glass-border);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.06);
}

.button.secondary:hover {
  background: var(--gac-surface-2);
}

.button.full { width: 100%; }

.button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

/* Theme toggle */
.theme-toggle {
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  border: 1px solid color-mix(in srgb, var(--gac-text) 14%, transparent);
  border-radius: 8px;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.085), rgba(255, 255, 255, 0.018)),
    color-mix(in srgb, var(--gac-page-bg) 46%, transparent);
  color: var(--gac-text);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.12),
    0 8px 22px color-mix(in srgb, var(--gac-glass-shadow) 55%, transparent);
  backdrop-filter: blur(18px) saturate(1.22);
  -webkit-backdrop-filter: blur(18px) saturate(1.22);
  cursor: pointer;
  transition: border-color 200ms ease, background 200ms ease, box-shadow 200ms ease;
}

.theme-toggle:hover {
  border-color: color-mix(in srgb, var(--gac-lime) 38%, var(--gac-glass-border));
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.14),
    0 8px 22px color-mix(in srgb, var(--gac-glass-shadow) 55%, transparent),
    0 0 20px color-mix(in srgb, var(--gac-lime) 10%, transparent);
}

.theme-toggle svg {
  width: 16px;
  height: 16px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.theme-moon { display: none; }
:root[data-theme="dark"] .theme-sun { display: none; }
:root[data-theme="dark"] .theme-moon { display: block; }

/* Footer */
.footer {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  width: min(var(--gac-canvas), 100%);
  margin: 96px auto 48px;
  padding: 36px 32px;
  border-top: 1px solid var(--gac-glass-border);
  color: var(--gac-subtle);
  font-size: 13px;
}

.footer-tagline {
  margin: 0;
  color: var(--gac-subtle);
  font-size: 12px;
  font-weight: 600;
}

.footer nav {
  display: flex;
  gap: 22px;
  font-weight: 600;
}

.footer nav a {
  transition: color 200ms ease;
}

.footer nav a:hover {
  color: var(--gac-text);
}

/* Focus */
:focus-visible {
  outline: 2px solid color-mix(in srgb, var(--gac-lime) 70%, transparent);
  outline-offset: 2px;
}

/* Reduced motion respect */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}