.center-image {
  display: block;
  margin-left: auto;
  margin-right: auto;
  max-width: 100%;
  height: auto;
  text-align: center;
}

.responsive-video {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  overflow: hidden;
  border-radius: 0.5em;
}

.responsive-video iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

.md-typeset table {
  margin-left: auto;
  margin-right: auto;
}

.youtube-video {
  position: relative;
  padding-bottom: 56.25%; /* 16:9 aspect ratio */
  height: 0;
  overflow: hidden;
  border-radius: 0.5em;
  margin-top: 1em;
  margin-bottom: 1em;
}

.youtube-video iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

form[id^="quiz"] {
  margin-top: 1em;
  margin-bottom: 1em;
  padding: 0.75em;
  border-left: 4px solid var(--md-primary-fg-color);
  background-color: var(--md-code-bg-color);
  border-radius: 6px;
}


/* === Page content links (unchanged from previous unified style) --- */
.md-typeset a {
  color: var(--md-accent-fg-color);
  font-weight: 500;
  text-decoration-line: underline;
  text-decoration-color: transparent;   /* invisible by default */
  text-decoration-thickness: 2px;
  text-underline-offset: 3px;
  transition: text-decoration-color 0.25s ease, color 0.25s ease, opacity 0.25s ease;
}

.md-typeset a:hover,
.md-typeset a:focus {
  text-decoration-color: currentColor;  /* fade-in underline */
  opacity: 0.9;
}

.md-typeset a:visited {
  color: var(--md-accent-fg-color);
  opacity: 0.85;
}

/* === Sidebar / menu links: keep original colors, just add faded underline === */
.md-nav__link {
  position: relative;
  text-decoration-line: underline;
  text-decoration-color: transparent;   /* hidden by default */
  text-decoration-thickness: 2px;
  text-underline-offset: 3px;
  transition: text-decoration-color 0.25s ease, opacity 0.25s ease;
}

.md-nav__link:hover,
.md-nav__link:focus {
  text-decoration-color: currentColor;  /* fade-in underline */
  opacity: 0.9;
}


/* docs/styles/extra.css */

/* Force a darker blue for the top header bar */
.md-header {
  background-color: #0D47A1 !important;
}

/* Optional: ensure text/icons contrast well */
.md-header, 
.md-header a, 
.md-header__button,
.md-header__title {
  color: #ffffff !important;
}