* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: "Segoe UI", -apple-system, BlinkMacSystemFont, "Helvetica Neue", Arial, sans-serif;
  color: var(--text_color);
  background:
    radial-gradient(circle at 10% 10%, #d9f4ff 0, transparent 40%),
    radial-gradient(circle at 90% 0%, #e4e9ff 0, transparent 35%),
    var(--page_bg);
}

.page-shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
}

.card {
  width: min(760px, 100%);
  background: var(--surface_bg);
  border: 1px solid var(--border_color);
  border-radius: 18px;
  box-shadow: 0 20px 50px rgba(23, 32, 51, 0.08);
  padding: 28px;
}

.app-header {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 18px;
  flex-wrap: wrap;
}

.app-header img {
  width: 64px;
  height: 64px;
  object-fit: contain;
}

.app-name {
  font-size: 1.25rem;
  font-weight: 700;
  margin: 0;
}

.app-link {
  color: inherit;
  text-decoration: none;
}

.app-link:hover {
  text-decoration: underline;
}

.app-tagline {
  margin: 2px 0 0;
  color: var(--muted_text);
  font-size: 0.95rem;
}

.theme-switcher {
  margin-left: auto;
  display: inline-flex;
  gap: 0;
}

.theme-btn {
  border: 1px solid var(--border_color);
  background: var(--secondary_bg);
  color: var(--secondary_text);
  border-radius: 8px;
  font-size: 0.95rem;
  width: 36px;
  height: 36px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  cursor: pointer;
}

.theme-btn:hover {
  background: var(--secondary_bg_hover);
}

.theme-btn.is-active {
  background: var(--main_color);
  border-color: var(--main_color);
  color: var(--text_on_main);
}

.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;
}

@media (max-width: 640px) {
  .card { padding: 22px; }
  .app-header img { width: 54px; height: 54px; }
  .theme-switcher { width: 100%; margin-left: 0; }
}