/* ============================================================
   Base / Reset
   ============================================================ */

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

html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--fs-base);
  line-height: var(--lh-normal);
  color: var(--text-base);
  background: var(--bg-app);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4, h5, h6 { margin: 0; color: var(--text-strong); line-height: var(--lh-tight); font-weight: var(--fw-bold); }
p { margin: 0; }
a { color: var(--brand-600); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; display: block; }
button { font-family: inherit; }
ul, ol { margin: 0; padding: 0; list-style: none; }

:focus-visible { outline: 3px solid var(--brand-300); outline-offset: 2px; border-radius: 4px; }

/* Reading passage typography (serif) */
.prose {
  font-family: var(--font-serif);
  font-size: var(--fs-lg);
  line-height: var(--lh-relaxed);
  color: var(--text-base);
}
.prose p + p { margin-top: var(--sp-4); }

/* Utility */
.container { width: 100%; max-width: var(--container); margin: 0 auto; padding: 0 var(--sp-6); }
.container--narrow { max-width: var(--container-narrow); }
.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;
}
.text-muted { color: var(--text-muted); }
.text-brand { color: var(--brand-600); }
.text-sm { font-size: var(--fs-sm); }
.text-xs { font-size: var(--fs-xs); }

/* selection */
::selection { background: var(--brand-200); color: var(--brand-900); }

/* scrollbar polish */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-thumb { background: var(--gray-300); border-radius: var(--r-full); border: 2px solid var(--bg-app); }
::-webkit-scrollbar-thumb:hover { background: var(--gray-400); }