:root {
  --bg: #fafaf7;
  --surface: #ffffff;
  --surface-2: #f3f3ee;
  --border: #e3e2dc;
  --text: #1c1c1a;
  --text-muted: #5b5b56;
  --accent: #2c5d8a;
  --accent-hover: #1f456a;
  --success: #2f7d4f;
  --warning: #b07d27;
  --radius: 10px;
  --shadow: 0 1px 2px rgba(0,0,0,.04), 0 4px 12px rgba(0,0,0,.04);
  --max: 960px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #131312;
    --surface: #1c1c1b;
    --surface-2: #232322;
    --border: #34332f;
    --text: #ececea;
    --text-muted: #9b9a93;
    --accent: #6fa8d6;
    --accent-hover: #94c1e6;
    --success: #5db380;
    --warning: #d6a85a;
    --shadow: 0 1px 2px rgba(0,0,0,.3), 0 6px 18px rgba(0,0,0,.25);
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Inter", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: var(--max);
  margin: 0 auto;
  padding: 32px 20px 80px;
}

a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-hover); text-decoration: underline; }

header.site {
  border-bottom: 1px solid var(--border);
  background: var(--surface);
}
header.site .inner {
  max-width: var(--max);
  margin: 0 auto;
  padding: 18px 20px;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
header.site h1 {
  margin: 0;
  font-size: 18px;
  font-weight: 600;
  letter-spacing: -0.01em;
}
header.site .meta {
  color: var(--text-muted);
  font-size: 13px;
}

h1.page-title {
  font-size: 32px;
  margin: 0 0 8px;
  letter-spacing: -0.02em;
}
.page-lead {
  color: var(--text-muted);
  font-size: 15px;
  margin: 0 0 32px;
}

h2 { font-size: 22px; margin: 40px 0 16px; letter-spacing: -0.01em; }
h3 { font-size: 16px; margin: 24px 0 8px; }

.breadcrumb {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 12px;
}
.breadcrumb a { color: var(--text-muted); }
.breadcrumb a:hover { color: var(--accent); }

/* Workflow box on landing */
.workflow {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 24px;
  margin: 24px 0 40px;
}
.workflow ol { margin: 8px 0 0 18px; padding: 0; }
.workflow li { margin: 4px 0; }
.workflow details { margin-top: 14px; }
.workflow summary {
  cursor: pointer;
  font-weight: 500;
  color: var(--accent);
  padding: 6px 0;
}

/* Module grid (landing) */
.module-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 16px;
}
.module-card {
  display: block;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  color: var(--text);
  text-decoration: none;
  transition: transform .15s ease, box-shadow .15s ease, border-color .15s ease;
  position: relative;
}
.module-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow);
  border-color: var(--accent);
  text-decoration: none;
}
.module-card.disabled {
  opacity: 0.65;
  cursor: not-allowed;
}
.module-card.disabled:hover {
  transform: none;
  border-color: var(--border);
  box-shadow: none;
}
.module-card .num {
  font-size: 12px;
  color: var(--text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.module-card .title {
  font-size: 17px;
  font-weight: 600;
  margin: 6px 0 8px;
}
.module-card .goal {
  font-size: 14px;
  color: var(--text-muted);
  margin: 0 0 14px;
}
.module-card .row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 12px;
  color: var(--text-muted);
}

.badge {
  display: inline-block;
  padding: 3px 9px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.02em;
}
.badge.available { background: rgba(47,125,79,.12); color: var(--success); }
.badge.soon { background: rgba(176,125,39,.14); color: var(--warning); }
.badge.complete { background: var(--accent); color: white; }

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 500;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  text-decoration: none;
  transition: all .15s ease;
}
.btn:hover { border-color: var(--accent); color: var(--accent); text-decoration: none; }
.btn.primary {
  background: var(--accent);
  color: white;
  border-color: var(--accent);
}
.btn.primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); color: white; }
.btn.disabled, .btn[disabled] { opacity: 0.5; cursor: not-allowed; pointer-events: none; }
.btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin: 18px 0 24px;
}

/* Video grid */
.video-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 18px;
  margin: 16px 0 32px;
}
@media (min-width: 720px) {
  .video-grid { grid-template-columns: repeat(2, 1fr); }
}
.video-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}
.video-card .frame {
  position: relative;
  aspect-ratio: 16/9;
  background: #000;
}
.video-card .frame iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
}
.video-card .meta {
  padding: 12px 14px;
  font-size: 13px;
}
.video-card .meta .title {
  font-weight: 500;
  color: var(--text);
  margin: 0 0 4px;
  line-height: 1.4;
}
.video-card .meta .sub {
  color: var(--text-muted);
  font-size: 12px;
}

/* Mobile NotebookLM how-to (compact, with collapsible details) */
.mobile-howto {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 18px;
  margin: 8px 0 24px;
}
.mh-summary {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 16px;
  align-items: center;
}
.mh-text h3 {
  margin: 0 0 4px;
  font-size: 15px;
  font-weight: 600;
}
.mh-text .mh-bullets {
  margin: 0;
  font-size: 13px;
  color: var(--text-muted);
}
.mobile-howto .qr-wrap {
  text-align: center;
  background: white;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px;
  align-self: center;
}
.mobile-howto .qr-wrap .qr-code { display: inline-block; line-height: 0; }
.mobile-howto .qr-wrap .qr-label {
  margin-top: 4px;
  font-size: 10px;
  color: #555;
  font-weight: 500;
  letter-spacing: 0.02em;
}
.mh-details {
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px dashed var(--border);
}
.mh-details > summary {
  cursor: pointer;
  font-size: 13.5px;
  font-weight: 500;
  color: var(--accent);
  list-style: none;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 0;
}
.mh-details > summary::-webkit-details-marker { display: none; }
.mh-details > summary::before {
  content: "▸";
  transition: transform .15s ease;
}
.mh-details[open] > summary::before { transform: rotate(90deg); }
.mh-details .why {
  background: var(--surface-2);
  border-left: 3px solid var(--accent);
  padding: 10px 14px;
  border-radius: 4px;
  margin: 12px 0;
  font-size: 13.5px;
}
.mh-details .why strong { color: var(--text); }
.mh-details .why ul { margin: 6px 0 0 16px; padding: 0; }
.mh-details .why li { margin: 3px 0; }
.mh-details ol { margin: 8px 0 0 18px; padding: 0; font-size: 13.5px; }
.mh-details ol li { margin: 4px 0; }
.mh-details .tip {
  margin-top: 10px;
  font-size: 12.5px;
  color: var(--text-muted);
  font-style: italic;
}

/* Concepts list */
.concepts {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 22px;
  margin: 8px 0 24px;
}
.concepts ul, .concepts ol { margin: 6px 0; padding-left: 20px; }
.concepts li { margin: 6px 0; }
.concepts strong { color: var(--text); }

/* Self-check */
.qa { display: flex; flex-direction: column; gap: 10px; margin: 8px 0 24px; }
.qa details {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 18px;
  transition: border-color .15s ease;
}
.qa details[open] { border-color: var(--accent); }
.qa summary {
  cursor: pointer;
  font-weight: 500;
  list-style: none;
  display: flex;
  align-items: flex-start;
  gap: 10px;
}
.qa summary::-webkit-details-marker { display: none; }
.qa summary::before {
  content: "▸";
  color: var(--accent);
  transition: transform .15s ease;
  flex-shrink: 0;
}
.qa details[open] summary::before { transform: rotate(90deg); }
.qa .answer {
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px dashed var(--border);
  color: var(--text-muted);
  font-size: 14.5px;
}
.qa .answer.tbd { font-style: italic; }

/* Resource cards */
.resources {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
  margin: 8px 0 24px;
}
@media (min-width: 720px) {
  .resources { grid-template-columns: repeat(2, 1fr); }
}
.resources a {
  display: block;
  padding: 12px 16px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface);
  font-size: 14px;
}
.resources a:hover { border-color: var(--accent); text-decoration: none; }

/* Footer */
footer.site {
  border-top: 1px solid var(--border);
  margin-top: 60px;
  padding: 24px 20px;
  font-size: 13px;
  color: var(--text-muted);
}
footer.site .inner {
  max-width: var(--max);
  margin: 0 auto;
}
footer.site table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 12px;
}
footer.site th, footer.site td {
  text-align: left;
  padding: 8px 10px;
  border-bottom: 1px solid var(--border);
  font-weight: 400;
}
footer.site th { font-weight: 600; color: var(--text); }

.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: var(--text);
  color: var(--bg);
  padding: 10px 18px;
  border-radius: 8px;
  font-size: 13px;
  opacity: 0;
  pointer-events: none;
  transition: opacity .2s ease, transform .2s ease;
  z-index: 100;
}
.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}