:root {
  --bg: #f6f7fb;
  --card: #ffffff;
  --text: #0f172a;
  --muted: #51608f;
  --accent: #2563eb;
  --container-w: 900px;
  --radius: 10px;
}

[data-theme="dark"] {
  --bg: #0b1220;
  --card: #071021;
  --text: #e6eef6;
  --muted: #9fb2d8;
  --accent: #5aa0ff;
}

* { box-sizing: border-box; }
html,body { height: 100%; margin: 0; font-family: system-ui, -apple-system, "Segoe UI", Roboto, Arial; background: var(--bg); color: var(--text); }
.container { max-width: var(--container-w); margin: 0 auto; padding: 1.25rem; }

.site-header { display:flex; align-items:center; justify-content:space-between; gap:1rem; padding: .5rem 0; }
.brand { font-weight: 700; font-size: 1.125rem; }

.hero { padding: 2.25rem 0; }
.hero h1 { margin: 0 0 .5rem; font-size: 1.75rem; }
.lead { margin: 0; color: var(--muted); font-size:1.05rem; }

.theme-toggle {
  border: none;
  background: transparent;
  cursor: pointer;
  padding: .25rem .5rem;
  border-radius: 6px;
  font-size: 1.05rem;
  color: var(--text);
}
.theme-toggle:focus { outline: 2px solid var(--accent); outline-offset: 2px; }

.site-footer { border-top: 1px solid rgba(0,0,0,0.06); padding: 1rem 0; margin-top: 2rem; color: var(--muted); display:flex; justify-content:space-between; gap:1rem; align-items:center; flex-wrap:wrap; }
.site-footer a { color: var(--muted); text-decoration:none; }
.site-footer a:hover { color: var(--accent); }

a { color: var(--accent); }

/* Social / icon buttons in footer */
.social-links { display: flex; gap: .5rem; align-items: center; }
.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  padding: 0;
  border-radius: 8px;
  border: none;
  background: transparent;
  color: var(--muted);
  text-decoration: none;
  transition: color .15s ease, background-color .15s ease, transform .06s ease;
}
.icon-btn svg { display: block; width: 18px; height: 18px; }
.icon-btn:hover { color: var(--accent); transform: translateY(-1px); }
.icon-btn:focus { outline: 2px solid var(--accent); outline-offset: 3px; color: var(--accent); }

/* screen-reader-only helper */
.sr-only {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

/* Small screens */
@media (max-width:520px) {
  .site-header, .site-footer { flex-direction: column; align-items: flex-start; }
}