/* ==========================================================================
   Base: reset, typography, page shell, focus styles, skip-link
   ========================================================================== */

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

html,
body {
  margin: 0;
  padding: 0;
}

html {
  color-scheme: dark;
}

body {
  background: var(--color-bg);
  color: var(--color-text);
  font-family: "Segoe UI", system-ui, -apple-system, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.5;
  min-height: 100vh;
}

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

a {
  color: var(--color-accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

h1,
h2,
h3,
h4,
p {
  margin: 0 0 var(--space-4) 0;
}

ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

/* ---- Visually-hidden utility (kept in a11y tree, unlike display:none) ---- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ---- Skip link ---- */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-3);
  z-index: 1000;
  background: var(--color-accent-strong);
  color: var(--white);
  padding: var(--space-3) var(--space-5);
  border-radius: 4px;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: var(--space-3);
}

/* ---- Global focus style ---- */
:focus-visible {
  outline: 2px solid var(--color-focus-ring);
  outline-offset: 2px;
}

/* ---- Page shell ---- */
.app-shell {
  position: relative;
  display: flex;
  min-height: 100vh;
}

.site-content {
  display: flex;
  flex-direction: column;
  flex: 1;
  min-width: 0;
}

.site-main {
  flex: 1;
}

/* ---- Mobile top bar (hidden on desktop by default) ---- */
.mobile-topbar {
  display: none;
}

@media (max-width: 768px) {
  .mobile-topbar {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    height: var(--topbar-height);
    padding: 0 var(--space-4);
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 20;
  }
}

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