:root {
  --navy: #003a73;
  --navy-dark: #002a54;
  --blue: #009fe6;
  --blue-soft: #e3f4fd;
  --ink: #1c2b36;
  --gray: #5b6b78;
  --line: #dde5ec;
  --bg: #f5f8fa;
  --white: #ffffff;
  --accent: #ff7a45;
  --green: #2bb673;
  --red: #e0443a;
  --radius: 14px;
  --shadow: 0 2px 12px rgba(0, 42, 84, 0.08);
}

* { box-sizing: border-box; }

body { margin: 0; font-family: 'Noto Sans JP', 'Inter', sans-serif; color: var(--ink); background: var(--bg); line-height: 1.8; }
.container { max-width: 980px; margin: 0 auto; padding: 0 20px; }

/* ---------- header / hero(共通) ---------- */
.site-header { position: sticky; top: 0; z-index: 100; background: var(--navy); box-shadow: 0 2px 8px rgba(0,0,0,.15); }
.header-inner { max-width: 980px; margin: 0 auto; padding: 0 20px; display: flex; align-items: center; justify-content: space-between; height: 58px; }
.logo { color: #fff; font-weight: 900; font-size: 17px; display: flex; align-items: center; gap: 10px; }
.logo-mark { display: inline-flex; align-items: center; justify-content: center; width: 30px; height: 30px; border-radius: 8px; background: var(--blue); color: #fff; font-weight: 800; font-size: 16px; flex-shrink: 0; }
.nav { display: flex; gap: 4px; flex-wrap: wrap; align-items: center; }
.nav a { color: #cfe3f5; text-decoration: none; font-size: 13px; font-weight: 500; padding: 6px 12px; border-radius: 999px; transition: .15s; }
.nav a:hover { background: rgba(255,255,255,.14); color: #fff; }
.nav .nav-home { background: rgba(255,255,255,.14); color: #fff; font-weight: 700; border: 1px solid rgba(255,255,255,.25); }
.nav .nav-home:hover { background: var(--blue); border-color: var(--blue); }

.hero { background: linear-gradient(135deg, var(--navy) 0%, #00518f 70%, #0070b8 100%); color: #fff; padding: 64px 0 56px; }
.hero-eyebrow { font-family: 'Inter', sans-serif; font-weight: 600; font-size: 12px; letter-spacing: .2em; color: #7fd0f5; margin: 0 0 10px; }
.hero h1 { font-size: 40px; font-weight: 900; margin: 0 0 16px; letter-spacing: .02em; }
.hero-lead { font-size: 15px; color: #d7e7f5; margin: 0 0 28px; }
.hero-lead strong { color: #fff; }
.hero-steps { display: flex; gap: 10px; flex-wrap: wrap; }
.step-chip { background: rgba(255,255,255,.12); border: 1px solid rgba(255,255,255,.3); color: #fff; text-decoration: none; font-size: 13px; font-weight: 700; padding: 8px 16px; border-radius: 999px; transition: .15s; }
.step-chip:hover { background: var(--blue); border-color: var(--blue); }

/* ---------- lesson(共通) ---------- */
.lesson { background: var(--white); border-radius: var(--radius); box-shadow: var(--shadow); padding: 36px 36px 32px; margin: 36px 0; }
.lesson-head { display: flex; align-items: center; gap: 14px; margin-bottom: 8px; }
.step-badge { background: var(--blue); color: #fff; font-family: 'Inter', sans-serif; font-weight: 800; font-size: 12px; letter-spacing: .08em; padding: 4px 12px; border-radius: 999px; }
.lesson h2 { font-size: 24px; font-weight: 900; color: var(--navy); margin: 0; }
.lesson-desc { color: var(--gray); font-size: 14.5px; margin: 10px 0 20px; }
.lesson-desc strong { color: var(--navy); }
.sub-head { color: var(--navy); font-size: 17px; margin: 32px 0 12px; }

.tips-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); gap: 14px; margin-top: 20px; }
.tip-card { background: var(--bg); border-radius: 10px; padding: 18px 18px 14px; border: 1px solid var(--line); }
.tip-card h3 { font-size: 14.5px; color: var(--navy); margin: 6px 0 6px; }
.tip-card p { font-size: 13px; color: var(--gray); margin: 0; line-height: 1.7; }
.tip-card p strong { color: var(--navy); }

/* ---------- STEP1 球の図解 ---------- */
.sphere-figure { display: flex; justify-content: center; }
.sphere-stage {
  position: relative; width: 100%; max-width: 620px; height: 340px;
  background: linear-gradient(180deg, #eef3f7 0%, #eef3f7 62%, #dde6ec 62%, #d2dde4 100%);
  border: 1px solid var(--line); border-radius: 12px;
}
.sphere {
  position: absolute; left: 50%; top: 64px; transform: translateX(-50%);
  width: 168px; height: 168px; border-radius: 50%;
  background:
    radial-gradient(circle at 38% 32%,
      #ffffff 0%, #f2f2f2 7%, #cfcfcf 26%, #8f8f8f 47%,
      #3c3c3c 66%, #2b2b2b 76%, #4a4a4a 90%, #3f3f3f 100%);
}
.cast-shadow {
  position: absolute; left: 50%; top: 224px; transform: translateX(-30%);
  width: 210px; height: 40px; border-radius: 50%;
  background: radial-gradient(ellipse at center, rgba(20,28,36,.42), rgba(20,28,36,.12) 55%, transparent 72%);
  filter: blur(1px);
}
.sp-label { position: absolute; font-size: 11.5px; color: var(--navy); background: rgba(255,255,255,.9); border: 1px solid var(--line); border-radius: 8px; padding: 5px 9px; line-height: 1.4; max-width: 168px; box-shadow: 0 2px 6px rgba(0,40,80,.08); }
.sp-label b { display: block; font-size: 12px; }
.sp-label small { color: var(--gray); font-size: 10.5px; }
.l-hi { left: 6%; top: 40px; }
.l-light { left: 4%; top: 150px; }
.l-mid { right: 4%; top: 56px; }
.l-core { right: 3%; top: 150px; }
.l-refl { right: 6%; top: 232px; }
.l-cast { left: 5%; top: 256px; }

/* ---------- STEP2 並べ替え ---------- */
.order-slots { display: flex; gap: 8px; margin-bottom: 14px; flex-wrap: wrap; }
.order-slot { flex: 1; min-width: 92px; height: 92px; border: 2px dashed var(--line); border-radius: 10px; display: flex; align-items: center; justify-content: center; position: relative; background: var(--bg); }
.order-slot .slot-num { position: absolute; top: 4px; left: 8px; font-size: 11px; font-weight: 800; color: #9fb0bd; font-family: 'Inter',sans-serif; }
.order-pool { display: flex; gap: 8px; flex-wrap: wrap; }
.tone-card { width: 92px; height: 92px; border-radius: 10px; border: 1.5px solid var(--line); cursor: pointer; position: relative; overflow: hidden; transition: transform .1s; }
.tone-card:hover { transform: translateY(-2px); }
.tone-card .tc-name { position: absolute; left: 0; right: 0; bottom: 0; font-size: 10.5px; font-weight: 700; text-align: center; padding: 3px 2px; background: rgba(255,255,255,.92); color: var(--ink); }
.tone-card.placed { visibility: hidden; }
.tone-card.in-slot { cursor: default; }
.tone-card.in-slot:hover { transform: none; }
.order-slot.show-correct { border: 2px solid var(--green); }
.order-slot.show-wrong { border: 2px solid var(--red); }

/* ---------- STEP3 光の向き(Canvas) ---------- */
.light-area { display: flex; gap: 20px; align-items: center; flex-wrap: wrap; }
#light-canvas { flex: 0 0 auto; border: 1px solid var(--line); border-radius: 12px; background: #eef3f7; width: 300px; height: 280px; }
.light-ctrls { flex: 1; min-width: 250px; display: flex; flex-direction: column; gap: 14px; }
.canvas-note { font-size: 13px; color: var(--gray); margin: 0; line-height: 1.7; min-height: 20px; }
.canvas-note strong { color: var(--navy); }
.chk { font-size: 13px; color: var(--ink); font-weight: 500; display: flex; align-items: center; gap: 7px; cursor: pointer; }
.chk input { accent-color: var(--blue); width: 16px; height: 16px; }
.vrow { display: flex; align-items: center; gap: 12px; }
.vlabel { flex-shrink: 0; min-width: 64px; font-size: 12.5px; font-weight: 800; color: var(--navy); }
.vrow input[type="range"] { flex: 1; accent-color: var(--navy); }
.vval { width: 46px; text-align: right; font-family: 'Inter',sans-serif; font-weight: 600; font-size: 13px; color: var(--navy); }

/* ---------- クイズ共通 ---------- */
.quiz-box { border: 2px solid var(--line); border-radius: 14px; background: #fff; padding: 26px 28px; }
.quiz-progress { display: flex; justify-content: space-between; align-items: center; font-family: 'Inter', sans-serif; font-weight: 600; font-size: 13px; color: var(--gray); margin-bottom: 12px; }
.quiz-q { font-size: 16.5px; font-weight: 900; color: var(--navy); margin-bottom: 16px; line-height: 1.7; }
.quiz-q .q-icon { font-size: 24px; margin-right: 6px; }
.quiz-opts { display: flex; flex-direction: column; gap: 9px; }
.quiz-opt { text-align: left; font-family: inherit; font-size: 14.5px; font-weight: 700; background: var(--bg); color: var(--ink); border: 2px solid var(--line); border-radius: 10px; padding: 11px 18px; cursor: pointer; transition: .12s; }
.quiz-opt:hover { border-color: var(--blue); background: var(--blue-soft); }
.quiz-opt.is-correct { border-color: var(--green); background: #f2fbf6; color: #1d7a4d; }
.quiz-opt.is-wrong { border-color: var(--red); background: #fdf0ef; color: #b3372f; }
.quiz-opt:disabled { cursor: default; }
.quiz-note { margin-top: 14px; background: var(--blue-soft); border-radius: 10px; padding: 12px 16px; font-size: 13.5px; color: var(--navy); font-weight: 500; }
.quiz-note[hidden] { display: none; }
.quiz-next { margin-top: 14px; }
.quiz-final { text-align: center; padding: 10px 0; }
.quiz-final .qf-score { font-family: 'Inter', sans-serif; font-weight: 800; font-size: 50px; color: var(--navy); }
.quiz-final .qf-score small { font-size: 18px; }
.quiz-final p { margin: 6px 0 14px; font-weight: 900; color: var(--navy); }

.verdict { margin-top: 16px; border-radius: 12px; padding: 14px 20px; font-size: 14px; font-weight: 700; line-height: 1.7; }
.verdict[hidden] { display: none; }
.verdict.ok { background: #f2fbf6; border: 1.5px solid var(--green); color: #1d7a4d; }
.verdict.ng { background: #fdf0ef; border: 1.5px solid var(--red); color: #b3372f; }

/* ---------- btn / toast / table / note ---------- */
.toolbar { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-top: 16px; }
.btn { font-family: inherit; font-size: 13.5px; font-weight: 700; padding: 9px 18px; border-radius: 999px; cursor: pointer; border: 1.5px solid var(--line); background: #fff; color: var(--navy); transition: .15s; }
.btn:hover { border-color: var(--blue); color: var(--blue); }
.btn-primary { background: var(--navy); border-color: var(--navy); color: #fff; }
.btn-primary:hover { background: var(--navy-dark); color: #fff; }
.btn-accent { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn-accent:hover { background: #e8642f; border-color: #e8642f; color: #fff; }
.btn-ghost { border-color: transparent; color: var(--gray); }
.status { font-size: 13px; color: var(--gray); margin-left: auto; }

.shortcut-table { width: 100%; border-collapse: collapse; font-size: 13.5px; }
.shortcut-table th, .shortcut-table td { text-align: left; padding: 10px 14px; border-bottom: 1px solid var(--line); }
.shortcut-table th { background: var(--bg); color: var(--navy); font-size: 12.5px; }
.note { margin-top: 18px; background: #fff8f0; border: 1px solid #ffd9bd; border-radius: 10px; padding: 16px 20px; font-size: 13.5px; color: #6b4a2f; }
.note strong { color: #b34a14; }
.toast { position: fixed; left: 50%; bottom: 28px; transform: translateX(-50%); background: var(--navy); color: #fff; font-size: 13.5px; font-weight: 700; padding: 10px 22px; border-radius: 999px; box-shadow: 0 6px 20px rgba(0,0,0,.25); z-index: 1000; transition: opacity .3s; max-width: 90vw; text-align: center; }
.toast[hidden] { display: none; }
.site-footer { background: var(--navy); color: #9fc0dd; text-align: center; padding: 24px 20px; font-size: 12.5px; margin-top: 48px; }
.site-footer p { margin: 0; }

/* ---------- ページ送りナビ ---------- */
.page-nav { display: flex; gap: 12px; align-items: stretch; margin: 44px auto 0; }
.pgnav { flex: 1; display: flex; flex-direction: column; justify-content: center; gap: 3px; text-decoration: none; background: #fff; border: 1.5px solid #dde5ec; border-radius: 12px; padding: 14px 18px; transition: .15s; box-shadow: 0 2px 12px rgba(0,42,84,.08); }
.pgnav:hover { border-color: #009fe6; transform: translateY(-2px); }
.pgnav.prev { text-align: left; }
.pgnav.next { text-align: right; }
.pgnav.top { flex: 0 0 130px; text-align: center; background: #003a73; border-color: #003a73; }
.pgnav.top .pgnav-dir, .pgnav.top .pgnav-name { color: #fff; }
.pgnav.top:hover { background: #002a54; border-color: #002a54; }
.pgnav-dir { font-size: 12px; font-weight: 700; color: #ff7a45; }
.pgnav-name { font-size: 14px; font-weight: 900; color: #003a73; }
.pgnav.is-disabled { visibility: hidden; }
@media (max-width: 560px) { .page-nav { flex-wrap: wrap; } .pgnav.top { order: -1; flex-basis: 100%; } }

@media (max-width: 700px) {
  .hero h1 { font-size: 26px; }
  .lesson { padding: 24px 18px; }
  .header-inner { flex-direction: column; height: auto; padding: 10px 20px; gap: 4px; }
  .status { margin-left: 0; width: 100%; }
  .sphere-stage { height: 300px; }
  .sp-label { font-size: 10.5px; max-width: 130px; }
  #light-canvas { width: 100%; max-width: 300px; }
}