/* ==========================================================================
   Base — Reset, Typography, Global Layout
   ========================================================================== */

/* ---- Reset ---- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-ui);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100dvh;
}

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

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

button {
  font: inherit;
  cursor: pointer;
  border: none;
  background: none;
  color: inherit;
}

ul, ol {
  list-style: none;
}

/* ---- Typography ---- */
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: 400;
  line-height: 1.2;
  letter-spacing: -0.01em;
}

h1 {
  font-size: clamp(28px, 5vw, 42px);
  color: var(--color-text);
}

h2 {
  font-size: clamp(22px, 3.5vw, 28px);
}

h3 {
  font-size: 20px;
}

p {
  line-height: 1.6;
}

/* ---- Layout ---- */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

/* ---- Top Bar ---- */
.topbar {
  position: sticky;
  top: 0;
  z-index: var(--z-topbar);
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  height: 56px;
  padding: 0 var(--space-md);
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid var(--color-border-light);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.topbar__brand {
  font-family: var(--font-heading);
  font-size: 18px;
  color: var(--color-text);
  letter-spacing: -0.02em;
  flex-shrink: 0;
}

.topbar__nav {
  display: flex;
  gap: var(--space-lg);
}

.topbar__link {
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
  position: relative;
  padding: var(--space-xs) 0;
}

.topbar__link:hover,
.topbar__link--active {
  color: var(--color-text);
}

.topbar__link--active::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--color-text);
  border-radius: 1px;
}

/* ---- Topbar Controls (AAA + EN toggle) ---- */
.topbar__controls {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  margin-left: auto;
  padding-left: var(--space-md);
}

.topbar__size {
  display: flex;
  align-items: center;
  gap: 1px;
  background: var(--color-border-light);
  border-radius: var(--radius-sm);
  padding: 2px;
}

.topbar__size-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  border-radius: 4px;
  font-weight: 600;
  color: var(--color-text-light);
  transition: all var(--transition-fast);
}

.topbar__size-btn:hover {
  color: var(--color-text-secondary);
}

.topbar__size-btn.active {
  background: var(--color-surface);
  color: var(--color-text);
  box-shadow: var(--shadow-sm);
}

.topbar__size-btn[data-size="small"]  { font-size: 11px; }
.topbar__size-btn[data-size="medium"] { font-size: 14px; }
.topbar__size-btn[data-size="large"]  { font-size: 17px; }

/* Hide topbar size controls on reader pages (sidebar has its own) */
.topbar.reader-active .topbar__size {
  display: none;
}

/* Mobile: shrink nav gap */
@media (max-width: 600px) {
  .topbar__nav {
    gap: var(--space-sm);
  }
  .topbar__controls {
    gap: 4px;
    padding-left: var(--space-sm);
  }
}

.topbar__back {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
}

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

.topbar__back svg {
  width: 18px;
  height: 18px;
}

/* ---- Progress Bar ---- */
.progress-track {
  position: sticky;
  top: 56px;
  z-index: var(--z-topbar);
  height: 3px;
  background: var(--color-border-light);
}

.progress-fill {
  height: 100%;
  background: var(--color-accent);
  transition: width 100ms linear;
  border-radius: 0 2px 2px 0;
}

/* ---- Footer ---- */
.footer {
  margin-top: var(--space-3xl);
  padding: var(--space-xl) var(--space-md);
  text-align: center;
  font-size: 13px;
  color: var(--color-text-light);
  border-top: 1px solid var(--color-border-light);
}

/* ---- Utility ---- */
.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;
}

.hidden {
  display: none !important;
}

/* ---- Scrollbar (subtle) ---- */
::-webkit-scrollbar {
  width: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border-radius: 3px;
}