.signup-prompt {
  width: min(30rem, calc(100vw - 3rem));
  box-sizing: border-box;
  max-height: calc(100dvh - 3rem);
  overflow: auto;
  border: 1px solid var(--nav-border, #777);
  border-radius: 1rem;
  padding: clamp(1.25rem, 4vw, 2rem);
  background: var(--nav-color-surface, #fff);
  color: var(--nav-color-text, #17212b);
}
.signup-prompt::backdrop { background: rgb(0 0 0 / 55%); }
.signup-prompt .nav-btn { margin: .5rem .5rem .5rem 0; }
.signup-prompt__notice { font-size: .875rem; }