/* Musiikin teorian aloitusnäkymä (book/index.html).
 * Mitat, pyöristykset ja otsikkohierarkia seuraavat Kitaraharjoittelijan aloitusnäkymää
 * (harjoittelija/style.css: .intro ja .learning-card), jotta osiot näyttävät saman sivuston osilta. */
:root {
  color-scheme: dark;
  --purple: #6d4aff;
  --purple-dark: #4b2fd6;
  --lavender: #b5a3ff;
  --bg: #16121f;
  --panel: #221b31;
  --text: #efeaff;
  --muted: #beb5d3;
  --line: #71638c;
  --good: #79e0ab;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
  line-height: 1.55;
}
a { color: var(--lavender); text-underline-offset: .18em; }
a:hover { color: var(--text); }
:focus-visible { outline: 2px solid #75e5c6; outline-offset: 2px; }
.theory-home { max-width: 1100px; margin: 0 auto; padding: 32px 18px 0; }
[id] { scroll-margin-top: 12px; }

/* Otsikkoalue */
.intro { max-width: 740px; margin-bottom: 24px; }
.eyebrow { margin: 0 0 6px; color: var(--lavender); font-size: 12px; letter-spacing: .16em; font-weight: 700; }
h1 { margin: 0 0 12px; font-size: clamp(26px, 5vw, 38px); line-height: 1.2; }
.intro > p:last-child { margin: 0; color: var(--muted); font-size: 18px; }
h2 { margin: 0 0 12px; font-size: 21px; line-height: 1.25; }

/* Jatka opiskelua */
.resume {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 14px 24px;
  padding: 20px; border: 1px solid var(--lavender); border-radius: 16px;
  background: linear-gradient(140deg, #2a2044, var(--panel) 70%);
}
.resume-body { flex: 1 1 320px; min-width: 0; }
.resume-body p { margin: 0; }
.resume-label { color: var(--lavender); font-size: 13px; font-weight: 700; letter-spacing: .06em; text-transform: uppercase; }
.resume-body .resume-title { margin-top: 4px; font-size: 19px; font-weight: 700; }
.resume-body .resume-chapter { margin-top: 2px; color: var(--text); }
.resume-body .resume-note { margin-top: 6px; color: var(--muted); font-size: 14px; }
.resume-bar { display: block; width: min(100%, 320px); height: 8px; margin-top: 10px; border-radius: 4px; background: var(--bg); overflow: hidden; }
.resume-bar > span { display: block; height: 100%; background: var(--good); border-radius: 4px; }
.resume-action {
  display: inline-flex; align-items: center; justify-content: center; min-height: 44px;
  padding: 10px 18px; border: 1px solid var(--lavender); border-radius: 10px;
  background: var(--purple-dark); color: #fff; font-weight: 700; text-decoration: none;
}
.resume-action:hover { background: #5a3de7; color: #fff; }

/* Lähtötason valinta: pieni avattava rivi kolmen ison kortin sijaan. */
.level-picker { margin: 14px 0 0; border: 1px solid #453854; border-radius: 12px; }
.level-picker summary {
  display: flex; flex-wrap: wrap; align-items: center; gap: 2px 12px; min-height: 44px;
  padding: 10px 16px; cursor: pointer; font-weight: 650;
}
.level-picker summary span { color: var(--muted); font-size: 14px; font-weight: 400; }
.level-picker[open] summary { border-bottom: 1px solid #453854; }
.level-picker ul { margin: 0; padding: 12px 16px 14px 34px; color: var(--muted); font-size: 15px; }
.level-picker li + li { margin-top: 8px; }
.level-picker li > a:first-child { font-weight: 700; }

/* Neljä oppimiskokonaisuutta */
.groups { margin-top: 36px; }
.group { margin: 0 0 14px; border: 1px solid var(--line); border-radius: 16px; background: var(--panel); }
.group[open] { border-color: var(--lavender); }
.group > summary {
  display: flex; align-items: center; gap: 18px; min-height: 100px; padding: 20px;
  border-radius: 15px; cursor: pointer; list-style: none;
}
.group > summary::-webkit-details-marker { display: none; }
.group > summary:hover { background: #1b1528; }
.group > summary:focus-visible { outline-offset: -2px; }
.group-number { display: grid; flex: 0 0 45px; place-items: center; height: 45px; border-radius: 12px;
  background: var(--bg); color: var(--lavender); font-weight: 750; font-size: 19px; }
.group-body { display: grid; flex: 1; gap: 4px; min-width: 0; }
.group-body strong { font-size: 19px; }
.group-body > span { color: var(--muted); line-height: 1.5; }
.group-progress { color: var(--good); font-size: 13px; font-weight: 700; }
.group-progress:empty { display: none; }
.group-arrow { flex: none; width: 14px; height: 14px; margin-right: 6px; border-right: 3px solid var(--lavender);
  border-bottom: 3px solid var(--lavender); transform: rotate(45deg) translate(-3px, -3px); transition: transform .15s; }
.group[open] .group-arrow { transform: rotate(-135deg) translate(-3px, -3px); }
.group-note { margin: 0; padding: 0 20px 4px 83px; color: var(--muted); font-size: 14px; }
.part-list { margin: 0; padding: 6px 20px 20px 83px; list-style: none; display: grid; gap: 8px; }
.part-list a {
  display: flex; align-items: flex-start; gap: 14px; padding: 12px 14px;
  border: 1px solid #453854; border-radius: 12px; background: var(--bg);
  color: var(--text); text-decoration: none;
}
.part-list a:hover { border-color: var(--lavender); }
.part-num { flex: 0 0 28px; color: var(--lavender); font-weight: 750; font-size: 17px; line-height: 1.4; }
.part-text { display: grid; flex: 1; gap: 3px; min-width: 0; }
.part-text strong { font-size: 16px; }
.part-text > span { color: var(--muted); font-size: 14px; }
.part-text small { color: var(--muted); font-size: 12.5px; opacity: .85; }
.part-status { flex: none; align-self: center; color: var(--muted); font-size: 13px; font-weight: 700; white-space: nowrap; }
.part-status.is-done { color: var(--good); }
.part-status::after { content: " →"; color: var(--lavender); }

/* Lisämateriaalit */
.extras { margin-top: 40px; padding-top: 24px; border-top: 1px solid #2d2444; }
.extras ul { margin: 0; padding-left: 20px; color: var(--muted); }
.extras li + li { margin-top: 6px; }
.tools-note { color: var(--muted); font-size: 14px; max-width: 720px; }
.site-footer {
  max-width: 1100px; margin: 48px auto 0; padding: 20px 18px 40px; border-top: 1px solid #2d2444;
  text-align: center; color: var(--muted); font-size: 13px;
}

@media (max-width: 640px) {
  .group-note { padding-left: 20px; }
  .part-list { padding-left: 14px; padding-right: 14px; }
}
@media (max-width: 470px) {
  .theory-home { padding-top: 24px; }
  .resume { padding: 16px; }
  .resume-action { width: 100%; }
  .group > summary { padding: 14px; gap: 12px; min-height: 80px; }
  .group-number { flex-basis: 35px; height: 35px; font-size: 15px; }
  .group-body strong { font-size: 17px; }
  .group-body > span { font-size: 14px; }
  .group-note { padding: 0 14px 4px; }
  .part-list { padding: 4px 10px 14px; }
  .part-list a { padding: 10px; gap: 10px; flex-wrap: wrap; }
  .part-num { flex-basis: 22px; }
  .part-text { flex-basis: calc(100% - 32px); }
  .part-status { margin-left: 32px; }
}
@media (prefers-reduced-motion: reduce) { .group-arrow { transition: none; } }