:root{
  --bg:          #ffffff;
  --bg-soft:     #f7f7f9;
  --pink:        #ff3d81;
  --pink-soft:   #fff0f5;
  --purple:      #9b7fe0;
  --purple-soft: #f3f0fc;
  --ink:         #17171c;
  --ink-dim:     #74747f;
  --line:        #e7e7ec;
}

*{ box-sizing:border-box; margin:0; padding:0; }

html,body{
  background:var(--bg);
  color:var(--ink);
  font-family:'Noto Sans JP', sans-serif;
  min-height:100%;
  word-break:keep-all;
  overflow-wrap:break-word;
}

body{
  display:flex;
  flex-direction:column;
  min-height:100vh;
}

a{ color:inherit; }

.wrap{
  width:100%;
  max-width:840px;
  margin:0 auto;
  padding:0 24px;
}

/* ---------- header ---------- */
header{
  border-bottom:1px solid var(--line);
  position:sticky;
  top:0;
  background:rgba(255,255,255,.92);
  backdrop-filter:blur(6px);
  z-index:10;
}
.header-inner{
  display:flex;
  align-items:center;
  justify-content:space-between;
  padding:16px 0;
}
.logo{
  display:flex;
  align-items:center;
  gap:8px;
  font-family:'Zen Kaku Gothic New', sans-serif;
  font-weight:700;
  font-size:15px;
  letter-spacing:.02em;
  text-decoration:none;
}
.logo-dot{
  width:9px; height:9px; border-radius:50%;
  background:linear-gradient(135deg, var(--pink), var(--purple));
}
nav{
  display:flex;
  gap:22px;
}
nav a{
  font-size:13px;
  font-weight:500;
  color:var(--ink-dim);
  text-decoration:none;
  padding:6px 2px;
  border-bottom:2px solid transparent;
  transition:color .15s ease, border-color .15s ease;
}
nav a:hover{
  color:var(--ink);
  border-color:var(--pink);
}
nav a.is-active{
  color:var(--ink);
  border-color:var(--pink);
}

/* ---------- page content ---------- */
main{ flex:1; }
.page{
  padding:48px 0 64px;
}
.eyebrow{
  display:inline-block;
  font-size:12px;
  letter-spacing:.14em;
  color:var(--pink);
  font-weight:700;
  margin-bottom:10px;
}
.page h1{
  font-family:'Zen Kaku Gothic New', sans-serif;
  font-weight:900;
  font-size:clamp(24px, 5vw, 32px);
  margin-bottom:20px;
}
.lead{
  color:var(--ink-dim);
  font-size:14px;
  line-height:1.9;
  margin-bottom:28px;
}
.lead.small{
  font-size:12px;
  margin-top:32px;
  margin-bottom:0;
}

/* steps (usage page) */
.steps{
  list-style:none;
  counter-reset:step;
  display:flex;
  flex-direction:column;
  gap:18px;
  margin:8px 0 36px;
}
.steps li{
  counter-increment:step;
  display:flex;
  gap:16px;
  padding:18px 20px;
  background:var(--bg-soft);
  border-radius:12px;
}
.steps li::before{
  content:counter(step);
  flex-shrink:0;
  width:28px;
  height:28px;
  border-radius:50%;
  background:var(--ink);
  color:#fff;
  font-size:13px;
  font-weight:700;
  display:flex;
  align-items:center;
  justify-content:center;
}
.steps li b{
  display:block;
  font-size:14px;
  margin-bottom:4px;
}
.steps li span{
  display:block;
  font-size:13px;
  color:var(--ink-dim);
  line-height:1.7;
}

/* step diagram (usage page) */
.step-diagram{
  display:flex;
  align-items:flex-start;
  justify-content:center;
  gap:8px;
  margin:8px 0 40px;
  padding:36px 20px;
  background:var(--bg-soft);
  border-radius:16px;
}
.step-item{
  display:flex;
  flex-direction:column;
  align-items:center;
  text-align:center;
  width:170px;
}
.step-icon{
  position:relative;
  width:56px;
  height:56px;
  color:var(--pink);
  display:flex;
  align-items:center;
  justify-content:center;
  margin-bottom:14px;
}
.step-icon svg{ width:44px; height:44px; }
.step-num{
  position:absolute;
  top:-6px;
  right:-6px;
  width:20px;
  height:20px;
  border-radius:50%;
  background:var(--ink);
  color:#fff;
  font-size:11px;
  font-weight:700;
  display:flex;
  align-items:center;
  justify-content:center;
}
.step-item b{
  font-size:14px;
  margin-bottom:4px;
}
.step-item span{
  font-size:12px;
  color:var(--ink-dim);
  line-height:1.6;
}
.step-arrow{
  color:var(--purple);
  flex-shrink:0;
  margin-top:22px;
}
.step-arrow svg{ width:22px; height:22px; }

/* song list (simple placeholder rows) */
.song-list{
  list-style:none;
  border-top:1px solid var(--line);
}
.song-list li{
  display:flex;
  justify-content:space-between;
  align-items:center;
  padding:16px 4px;
  border-bottom:1px solid var(--line);
  font-size:14px;
}
.song-name{ font-weight:500; }
.song-status{
  font-size:12px;
  color:var(--ink-dim);
}

/* song cards */
.song-cards{
  list-style:none;
  display:flex;
  flex-direction:column;
  gap:16px;
  margin:20px 0 36px;
}
.song-card{
  display:flex;
  gap:18px;
  align-items:center;
  border:1px solid var(--line);
  border-radius:14px;
  padding:14px;
}
.song-thumb{
  position:relative;
  flex-shrink:0;
  width:180px;
  aspect-ratio:16/9;
  border-radius:10px;
  overflow:hidden;
  display:block;
  background:var(--bg-soft);
}
.song-thumb iframe{
  width:100%;
  height:100%;
  border:0;
  display:block;
}
.song-info{
  display:flex;
  flex-direction:column;
  gap:10px;
}
.song-info b{
  font-size:15px;
}
.btn-sm{
  display:inline-flex;
  align-items:center;
  gap:6px;
  width:fit-content;
  text-decoration:none;
  background:linear-gradient(135deg, var(--pink), var(--purple));
  color:#fff;
  font-weight:700;
  font-size:12px;
  padding:8px 14px;
  border-radius:8px;
}
.btn-sm svg{ width:14px; height:14px; }

/* CTA button (reused on subpages) */
.btn{
  display:inline-flex;
  align-items:center;
  gap:10px;
  text-decoration:none;
  background:linear-gradient(135deg, var(--pink), var(--purple));
  color:#ffffff;
  font-weight:700;
  font-size:14px;
  padding:13px 24px;
  border-radius:10px;
  transition:transform .15s ease, box-shadow .15s ease;
}
.btn:hover{
  transform:translateY(-2px);
  box-shadow:0 10px 24px rgba(155,127,224,.35);
}

/* ---------- footer ---------- */
footer{
  border-top:1px solid var(--line);
  background:var(--bg-soft);
  padding:20px 0 28px;
}
footer p{
  font-size:11px;
  line-height:1.9;
  color:var(--ink-dim);
  text-align:center;
}

/* ---------- mobile ---------- */
@media (max-width:640px){
  .wrap{ padding:0 16px; }
  .header-inner{ padding:12px 0; }
  .logo{ font-size:13px; }
  nav{ gap:14px; }
  nav a{ font-size:12px; }

  .page{ padding:32px 0 48px; }
  .page h1{ margin-bottom:14px; }
  .lead{ margin-bottom:22px; }

  .steps li{ padding:14px 16px; }

  .step-diagram{
    flex-direction:column;
    align-items:center;
    gap:4px;
    padding:24px 16px;
    margin:8px 0 28px;
  }
  .step-item{ width:100%; max-width:280px; }
  .step-arrow{
    margin-top:0;
    transform:rotate(90deg);
  }

  .song-card{
    flex-direction:column;
    align-items:stretch;
    padding:12px;
  }
  .song-thumb{ width:100%; }
  .song-info{ padding-top:2px; }
}