<button
  id="theme-switch"
  class="button outline icon-only"
  title="Switch to dark theme"
>
  <svg
    id="theme-switch-dark-icon"
    fill="currentColor"
    viewBox="0 0 20 20"
    xmlns="http://www.w3.org/2000/svg"
    ><path d="M17.293 13.293A8 8 0 016.707 2.707a8.001 8.001 0 1010.586 10.586z"
    ></path></svg
  >
  <svg
    id="theme-switch-light-icon"
    class="hidden"
    fill="currentColor"
    viewBox="0 0 20 20"
    xmlns="http://www.w3.org/2000/svg"
    ><path
      d="M10 2a1 1 0 011 1v1a1 1 0 11-2 0V3a1 1 0 011-1zm4 8a4 4 0 11-8 0 4 4 0 018 0zm-.464 4.95l.707.707a1 1 0 001.414-1.414l-.707-.707a1 1 0 00-1.414 1.414zm2.12-10.607a1 1 0 010 1.414l-.706.707a1 1 0 11-1.414-1.414l.707-.707a1 1 0 011.414 0zM17 11a1 1 0 100-2h-1a1 1 0 100 2h1zm-7 4a1 1 0 011 1v1a1 1 0 11-2 0v-1a1 1 0 011-1zM5.05 6.464A1 1 0 106.465 5.05l-.708-.707a1 1 0 00-1.414 1.414l.707.707zm1.414 8.486l-.707.707a1 1 0 01-1.414-1.414l.707-.707a1 1 0 011.414 1.414zM4 11a1 1 0 100-2H3a1 1 0 000 2h1z"
      fill-rule="evenodd"
      clip-rule="evenodd"></path></svg
  >
</button>

<script is:inline>
const themeSwitch = document.getElementById('theme-switch');
const themeSwitchDarkIcon = document.getElementById('theme-switch-dark-icon');
const themeSwitchLightIcon = document.getElementById(
  'theme-switch-light-icon'
);
const applyTheme = (theme) => {
  localStorage.setItem('theme', theme);
  themeSwitch.setAttribute(
    'title',
    `Switch to ${theme === 'dark' ? 'light' : 'dark'} theme`
  );

  if (theme === 'dark') {
    document.body.classList.add('dark');
    themeSwitchLightIcon.classList.remove('hidden');
    themeSwitchDarkIcon.classList.add('hidden');
  } else {
    document.body.classList.remove('dark');
    themeSwitchLightIcon.classList.add('hidden');
    themeSwitchDarkIcon.classList.remove('hidden');
  }
};

if (
  !localStorage.getItem('theme') &&
  window.matchMedia &&
  window.matchMedia('(prefers-color-scheme: dark)').matches
) {
  localStorage.setItem('theme', 'dark');
}

applyTheme(localStorage.getItem('theme') || 'light');

themeSwitch.addEventListener('click', () =>
  applyTheme(localStorage.getItem('theme') === 'dark' ? 'light' : 'dark')
);
</script>

<style>
  svg {
    width: var(--font-size);
    color: var(--font-color);
  }

  #theme-switch {
    color: var(--font-color);
  }

  .hidden {
    display: none;
  }
</style>
