:root {
  --left: 380px;
  --gap: 12px;
  --bg: #444;
  --lightest-blue: #8795ce;
  --lighter-blue: #6371a3;
  --dark-blue: #293046;
  --dark-blue-transparent: #293046dd;
  --darker-blue: #1b2340;
  --border: #232a3b;

  /* Fixed heights */
  --site-header-h: 64px; /* height of header.html (adjust if needed) */
  --topbar-h: 48px; /* height of the page topbar */

  /* Z-index layers */
  --z-site-header: 1400;
  --z-topbar: 1300;
  --z-drawer: 1200;
  --z-scrim: 1100;
}
* {
  box-sizing: border-box;
}
html,
body {
  height: 100%;
}
body {
  margin: 0;
  background: var(--bg);
  color: var(--offwhite);
}

/* Header */
.topbar {
  position: sticky;
  top: 0;
  z-index: 1000;
  display: grid;
  grid-template-columns: 1fr auto 1fr; /* left controls | title | right controls */
  align-items: center;
  gap: 12px;
  padding: 10px 14px;
  background: var(--dark-blue-transparent);
  color: var(--offwhite);
  border-bottom: 1px solid var(--border);
}
.topbar h1 {
  margin: 0;
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.2px;
  text-align: center;
  grid-column: 2;
}
.topbar .spacer {
  flex: 1;
}
.topbar-sub {
  opacity: 0.75;
  text-align: center;
  grid-column: 2;
  margin-left: 2rem;
}

/* Layout */
.layout {
  display: grid;
  grid-template-columns: var(--left) 1fr;
  gap: var(--gap);
  padding: var(--gap);
}
.left {
  min-width: 300px;
  overflow: auto;
  padding-right: 6px;
}
.left a {
  color: var(--lightest-blue);
  text-decoration: none;
}
.left a:hover {
  color: var(--offwhite);
  text-decoration: underline;
}
.right {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-md);
  background: var(--dark-blue);
}

/* Panels */
.panel {
  background: var(--dark-blue-transparent);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 0.6rem 0.7rem;
  margin-bottom: 0.6rem;
  box-shadow: 0 8px 18px var(--dark-blue-transparent) inset;
}
.panel h3 {
  margin: 0.1rem 0 0.6rem;
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--offwhite);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin: 0.4rem 0;
  flex-wrap: wrap;
}
.row label {
  opacity: 0.9;
  min-width: 78px;
}

select,
input[type="range"],
input[type="color"],
input[type="file"],
button {
  background: var(--border);
  border: 1px solid var(--border);
  color: var(--offwhite);
  border-radius: var(--radius-sm);
  padding: 0.35rem 0.5rem;
  font: inherit;
}
input[type="range"] {
  width: 220px;
}

.value {
  font-variant-numeric: tabular-nums;
  opacity: 0.9;
  min-width: 52px;
  text-align: right;
}

/* 2-line slider rows */
.row-ctl {
  display: flex;
  flex-direction: column;
  align-items: stretch;
}
.row-ctl > .ctl {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.row-ctl > .ctl > input[type="range"] {
  flex: 1 1 auto;
  min-width: 0;
}
.row-ctl > .ctl > .value {
  margin-left: auto;
  min-width: 52px;
  text-align: right;
}

.tabs button[data-active="true"] {
  background: var(--darker-blue);
  border-color: var(--lighter-blue);
}

.muted {
  opacity: 0.75;
}

.divider {
  height: 1px;
  background: var(--border);
  margin: 0.6rem 0;
  border-radius: var(--radius-xs);
}

/* Canvas fill */
#stage,
#stage canvas {
  position: absolute;
  inset: 0;
  width: 100% !important;
  height: 100% !important;
  display: block;
  background: var(--bg);
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
}

/* Morph list can grow tall */
#morphList {
  display: block;
}

body.viewport-shell {
  display: grid;
  grid-template-rows: auto 1fr auto;
  min-height: 100dvh;
}

/* Make only the middle area scroll if taller than the viewport */
#page-main {
  min-height: 0; /* IMPORTANT: allow the grid track to shrink */
  overflow: auto; /* internal scrolling for content */
}

/* If your header was sticky, you can drop sticky now */
.topbar {
  position: relative;
  top: 0;
  z-index: 1;
}

/* Optional: ensure your right-hand canvas still fills its box */
#stage,
#stage canvas {
  inset: 0;
  width: 100% !important;
  height: 100% !important;
}

#page-main {
  min-height: 0;
} /* allow it to shrink inside the 1fr row */

/* Replace your old .layout height:100dvh with this */
.layout {
  display: grid;
  grid-template-columns: var(--left, 380px) 1fr;
  gap: var(--gap, 12px);
  height: 100%; /* fill the #page-main row */
  min-height: 0; /* critical for grid children */
  overflow: hidden; /* prevent the whole layout from scrolling */
}

/* Left column: the only scrollable region */
.left {
  overflow: auto;
  min-height: 0;
}

/* Right column: lock the canvas, never scroll */
.right {
  position: relative;
  overflow: hidden;
  min-height: 0;
}
#stage,
#stage canvas {
  position: absolute;
  inset: 0;
  width: 100% !important;
  height: 100% !important;
  display: block;
}

footer {
  margin-top: 0rem;
  padding: 0rem 0rem 0.5rem;
  z-index: -1;
}

/* Default: 2-column layout */
.layout {
  display: grid;
  grid-template-columns: var(--left, 380px) 1fr;
  gap: var(--gap, 12px);
  height: 100%;
  min-height: 0;
  overflow: hidden;
}

/* ===== Header / Nav =====
DARK MODE */
header.site-header {
  background: var(--dark-blue);
  border-bottom: 3px solid var(--border);
  color: var(--offwhite);
}

nav a {
  color: inherit;
  border: 3px solid var(--border);
  background: var(--lighter-blue);
  box-shadow: 0 6px 0 var(--border);
}
/* Tint nav buttons on hover */
nav a:hover {
  background: var(--lightest-blue);
  /* slight lift */
  box-shadow: 0 8px 0 var(--border), 0 8px 18px rgba(0, 0, 0, 0.25);
}

.logo img {
  border: 3px solid var(--border);
  box-shadow: 0 4px 0 var(--border);
}

/* Toggle button */
.nav-toggle {
  border: 3px solid var(--border);
  background: var(--lighter-blue);
  box-shadow: 0 4px 0 var(--border);
}

.nav-toggle .nav-toggle-bar {
  background: var(--border);
}

.nav-toggle:active {
  box-shadow: 0 2px 0 var(--border);
}

/* Ensure the hamburger button area doesn’t introduce a different bg */
.site-header .nav-toggle,
.site-header .nav-toggle:focus-visible {
  background: var(--lighter-blue);
}

.site-header .nav-toggle:hover {
  background: var(--lightest-blue);
  color: var(--offwhite);
}

/* Show toggle & style bars on small screens */
@media (max-width: 768px) {
  .nav-toggle {
    border: 3px solid var(--border);
    background: var(--lighter-blue);
    box-shadow: 0 4px 0 var(--border);
    /* above dropdown */
  }

  /* Navigation background menu */
  .nav-links {
    background: var(--lighter-blue);
    border: 3px solid var(--border);
    box-shadow: 0 12px 0 var(--border), 0 12px 24px rgba(0, 0, 0, 0.25);
    background-color: var(--dark-blue-transparent);
    z-index: 1;
  }

  /* The bars */
  .nav-toggle span {
    background-color: var(--border) !important;
  }
}

/* =========================
   Mobile drawer for the left panel
========================= */
.panel-toggle {
  display: none;
}

.scrim[hidden] {
  display: none !important;
}

@media (max-width: 720px) {
  /* Show the small toggle button in the topbar */
  .panel-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    margin-right: 0.5rem;
    border-radius: 8px;
    background: var(--border);
    border: 1px solid var(--border);
    color: var(--offwhite);
    font-size: 20px;
    line-height: 1;
  }

  /* Center the title contents when the button appears */
  .topbar {
    justify-content: center;
    gap: 0.5rem;
  }

  /* Collapse to one column; canvas takes the grid slot */
  .layout {
    grid-template-columns: 1fr !important;
    overflow: visible; /* let the overlay escape */
  }

  /* Make the left panel an off-canvas drawer */
  .left#sidebar {
    position: fixed;
    top: var(--gap, 12px);
    bottom: var(--gap, 12px);
    left: 0;
    width: min(92vw, 360px);
    max-width: 92vw;
    z-index: 1000;
    background: var(--dark-blue);
    border-right: 1px solid var(--border);
    box-shadow: 20px 0 40px rgba(0, 0, 0, 0.45);
    overflow: auto;
    transform: translateX(-100%);
    transition: transform 0.28s ease;
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    padding-right: 6px;
  }

  /* Dark scrim behind the drawer */
  .scrim {
    position: fixed;
    z-index: 900;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-medium);
  }

  /* When open, slide in and activate scrim */
  body.menu-open .left#sidebar {
    transform: translateX(0);
  }
  body.menu-open .scrim {
    opacity: 1;
    pointer-events: auto;
  }

  /* Ensure canvas fills available space behind overlay */
  .right {
    grid-column: 1 / -1;
  }
}

/* Fixed heights and z-index moved to first :root block */

.topbar {
  position: sticky;
  top: 0;
  z-index: var(--z-topbar);

  display: grid;
  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
  align-items: center;
  gap: 12px;

  height: var(--topbar-h); /* fixed height */
  padding: 0 14px; /* no vertical padding that adds height */
  background: var(--dark-blue-transparent);
  color: var(--offwhite);
  border-bottom: 1px solid var(--border);
  overflow: hidden; /* prevent content from pushing height */
  z-index: 1;
}

.topbar h1 {
  grid-column: 2;
  margin: 0;
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.2px;
  text-align: center;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.topbar-sub {
  grid-column: 2;
  margin-left: 2rem;
  opacity: 0.75;
  text-align: center;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

body.viewport-shell {
  display: grid;
  grid-template-rows:
    auto /* header.html */
    var(--topbar-h) /* the sticky topbar */
    1fr /* content */
    auto; /* footer */
  min-height: 100dvh;
}

#page-main {
  min-height: 0;
  overflow: auto; /* only the middle scrolls */
}

@media (max-width: 720px) {
  /* Show the small toggle button in the topbar */
  .panel-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    margin-right: 0.5rem;
    border-radius: 8px;
    background: var(--border);
    border: 1px solid var(--border);
    color: var(--offwhite);
    font-size: 20px;
    line-height: 1;
  }

  .topbar {
    justify-content: center;
    gap: 0.5rem;
  }

  .layout {
    grid-template-columns: 1fr !important;
    overflow: visible; /* allow drawer to escape grid */
  }

  /* IMPORTANT: drawer begins under header+topbar */
  .left#sidebar {
    position: fixed;
    top: calc(var(--site-header-h) + var(--topbar-h) + var(--gap));
    bottom: var(--gap);
    left: 0;

    width: min(92vw, 360px);
    max-width: 92vw;
    z-index: var(--z-drawer);

    background: var(--dark-blue);
    border-right: 1px solid var(--border);
    box-shadow: 20px 0 40px rgba(0, 0, 0, 0.45);
    overflow: auto;

    transform: translateX(-100%);
    transition: transform 0.28s ease;
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    padding-right: 6px;
  }

  /* Scrim sits UNDER the header+topbar, so it never covers them */
  .scrim {
    position: fixed;
    z-index: var(--z-scrim);
    left: 0;
    right: 0;
    top: calc(var(--site-header-h) + var(--topbar-h));
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-medium);
  }
  .scrim[hidden] {
    display: none !important;
  }

  body.menu-open .left#sidebar {
    transform: translateX(0);
  }
  body.menu-open .scrim {
    opacity: 1;
    pointer-events: auto;
  }

  .right {
    grid-column: 1 / -1;
  }
}