:root{
  --bg:#0b1220;
  --panel:#111a2e;
  --text:#e8eefc;
  --muted:#b6c2e2;
  --accent:#7aa2ff;
  --line:rgba(255,255,255,.14);
  --shadow: 0 10px 30px rgba(0,0,0,.35);
  --radius: 16px;
  --max: 980px;
}

@media (prefers-color-scheme: light){
  :root{
    --bg:#f6f7fb;
    --panel:#ffffff;
    --text:#0b1220;
    --muted:#475569;
    --accent:#2f6bff;
    --line:rgba(15,23,42,.12);
    --shadow: 0 10px 25px rgba(2,6,23,.10);
  }
}

*{box-sizing:border-box}
html{scroll-behavior:smooth}

body{
  margin:0;
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto,
               "Hiragino Sans", "Noto Sans JP", "Yu Gothic", "Meiryo", Arial, sans-serif;
  background: radial-gradient(1200px 700px at 20% -10%, rgba(122,162,255,.28), transparent 60%),
              radial-gradient(900px 600px at 100% 0%, rgba(122,162,255,.18), transparent 55%),
              var(--bg);
  color:var(--text);
  line-height:1.75;
}

a{color:inherit}
a:hover{color:var(--accent)}

.skip{
  position:absolute; left:-9999px; top:auto;
  width:1px; height:1px; overflow:hidden;
}
.skip:focus{
  left:16px; top:16px;
  width:auto; height:auto;
  padding:10px 12px;
  background:var(--panel);
  border:1px solid var(--line);
  border-radius:999px;
  z-index:9999;
}

.container{
  max-width:var(--max);
  margin:0 auto;
  padding:24px 18px 64px;
}

/* Header */
header{
  position:sticky; top:0; z-index:50;
  backdrop-filter: blur(10px);
  background: linear-gradient(to bottom, rgba(11,18,32,.70), rgba(11,18,32,.25));
  border-bottom: 1px solid var(--line);
}
@media (prefers-color-scheme: light){
  header{
    background: linear-gradient(to bottom, rgba(246,247,251,.85), rgba(246,247,251,.35));
  }
}

.header-inner{
  max-width:var(--max);
  margin:0 auto;
  padding:14px 18px;
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:12px;
}

.brand{
  display:flex;
  align-items:center;
  gap:10px;
  text-decoration:none;
  font-weight:700;
}

.dot{
  width:10px;
  height:10px;
  border-radius:50%;
  background:var(--accent);
  box-shadow: 0 0 0 6px rgba(122,162,255,.18);
}

nav{
  display:flex;
  gap:14px;
  flex-wrap:wrap;
  align-items:center;
  font-size:14px;
}
nav a{
  text-decoration:none;
  color:var(--muted);
  padding:6px 10px;
  border-radius:999px;
  border:1px solid transparent;
}
nav a:hover{
  color:var(--text);
  border-color:var(--line);
  background:rgba(255,255,255,.06);
}

.pdfbox{
  border: 1px solid var(--line);
  border-radius: 12px;
  overflow: hidden;
  background: var(--panel);
  height: 78vh;
  min-height: 900px;
  position: relative; /* ★追加 */
}

/* Dropbox iframe を強制的にpdfbox全面へ */
.pdfbox iframe[src*="dropbox.com/dropins/embed"]{
  position: absolute;
  inset: 0;
  width: 100% !important;
  height: 100% !important;
  border: 0 !important;
  display: block;
}

/* Layout */
.hero{
  position: relative;
  min-height: 180px;
  margin-top:22px;
  overflow: hidden;
  display:flex;
  align-items:flex-end;
}
@media (max-width: 860px){
  .hero{grid-template-columns: 1fr}
}

.grid-2{
  display:grid;
  grid-template-columns: 1fr 1fr;
  gap:18px;
  margin-top:18px;
}
@media (max-width: 860px){
  .grid-2{grid-template-columns: 1fr}
}

section{margin-top:18px}
section h2{
  margin:0 0 10px;
  font-size:18px;
  letter-spacing:.2px;
}

/* Card */
.card{
  background: linear-gradient(180deg, rgba(255,255,255,.08), rgba(255,255,255,.03));
  border:1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding:20px;
}
@media (prefers-color-scheme: light){
  .card{ background: var(--panel); }
}

h1{
  margin:0 0 8px;
  font-size:34px;
  line-height:1.25;
  letter-spacing:.2px;
}
.subtitle{color:var(--muted); margin:0 0 14px}

h2{
  font-size: 24px;
}

.h2-section{
  font-size: 24px;
  color: rgb(34, 110, 147);
}

/* Badges / Buttons */
.badge-row{display:flex; gap:10px; flex-wrap:wrap; margin:14px 0 0}
.badge{
  font-size:13px;
  color:var(--muted);
  border:1px solid var(--line);
  border-radius:999px;
  padding:6px 10px;
  background:rgba(255,255,255,.04);
}

.btn-row{display:flex; gap:10px; flex-wrap:wrap; margin-top:16px}
.btn{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  padding:10px 12px;
  border-radius:12px;
  border:1px solid var(--line);
  text-decoration:none;
  font-weight:600;
  font-size:14px;
  background:rgba(255,255,255,.06);
}
.btn.primary{
  border-color:rgba(122,162,255,.45);
  background: rgba(122,162,255,.18);
}
.btn:hover{transform: translateY(-1px)}
.btn:active{transform: translateY(0)}

/* Content blocks */

ul{margin:8px 0 0; 
   padding-left:18px;
   color:var(--muted);
   font-size: 15px;
   color: #0b1220;
  }
li{margin:6px 0}
.list-tight li{margin:4px 0}

.item{
  padding:12px 12px;
  border:1px solid var(--line);
  border-radius:14px;
  background:rgba(255,255,255,.04);
  margin-top:10px;
}
.item-title{margin:0; font-weight:700}
.item-meta{margin:2px 0 0; color:var(--muted); font-size:13px}
.item-desc{margin:8px 0 0; color:var(--muted)}

.pill-row{display:flex; gap:8px; flex-wrap:wrap; margin-top:10px}
.pill{
  font-size:12px;
  color:var(--muted);
  border:1px solid var(--line);
  border-radius:999px;
  padding:4px 8px;
}

/* Inline code */
code.inline{
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas,
               "Noto Sans Mono CJK JP", "Courier New", monospace;
  padding:2px 6px;
  border:1px solid var(--line);
  border-radius:8px;
  background:rgba(255,255,255,.05);
  color:var(--text);
}

/* Footer */
footer{
  margin-top:28px;
  color:var(--muted);
  font-size:13px;
  text-align:center;
}

/* Topbar (Workshop pages) */
.topbar{
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--panel) 78%, transparent);
  backdrop-filter: blur(10px);
}

.topbar__inner{
  max-width: var(--max);
  margin: 0 auto;
  padding: 10px 18px;
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 12px;
}

.topbar .brand{
  font-weight: 800;
  letter-spacing: .02em;
  text-decoration: none;
  font-size: clamp(18px, 1.9vw, 24px);
  line-height: 1;
}

.topbar .nav{
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 8px;
  flex-wrap: wrap;
}

.topbar .nav__link{
  text-decoration: none;
  color: var(--muted);
  font-size: 18px;
  font-weight: 600;
  line-height: 1;
  padding: 9px 12px;
  border: 1px solid transparent;
  border-radius: 999px;
  transition: .2s ease;
}

.topbar .nav__link:hover{
  color: var(--text);
  border-color: var(--line);
  background: rgba(255,255,255,.08);
}

.search input{
  width: min(240px, 40vw);
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255,255,255,.04);
  color: var(--text);
  padding: 8px 12px;
  outline: none;
}

.search input::placeholder{
  color: var(--muted);
}

.search input:focus{
  border-color: color-mix(in srgb, var(--accent) 50%, var(--line));
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 15%, transparent);
}

.hamburger{
  display: none;
  width: 42px;
  height: 42px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: rgba(255,255,255,.04);
  cursor: pointer;
  align-items: center;
  justify-content: center;
  gap: 4px;
  flex-direction: column;
}

.hamburger span{
  display: block;
  width: 18px;
  height: 2px;
  background: var(--text);
}

.topbar .nav--mobile{
  display: none;
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 18px 12px;
}

.topbar .nav--mobile.is-open{
  display: grid;
  grid-template-columns: 1fr;
  gap: 6px;
}

@media (max-width: 920px){
  .topbar__inner{
    grid-template-columns: auto 1fr auto;
  }

  .topbar .nav--pc,
  .topbar .search{
    display: none;
  }

  .hamburger{
    display: inline-flex;
    justify-self: end;
  }

  .topbar .nav--mobile .nav__link{
    display: block;
    border-color: var(--line);
    background: rgba(255,255,255,.04);
  }
}

.hero__inner{
  position: relative;
  z-index: 1;
  max-width: var(--max);
  width: 100%;
  margin: 0 auto;
  padding: 0 18px 16px;
}

.hero__bg{
  position: absolute;
  inset: 0;
  background-size: cover;
  background-position: center;
}

.hero__overlay{
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,.28);
}

@media (max-width: 860px){
  .hero__inner{
    padding: 0 18px 20px;
  }
}

.dropdown{
  position: relative;
  display: inline-block;
}

.dropdown__toggle{
  background: none;
  border: none;
  cursor: pointer;
  font: inherit;
  color: inherit;
  padding: 0;
}

.dropdown__menu{
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  min-width: 160px;
  background: #fff;
  border: 1px solid #ddd;
  box-shadow: 0 4px 12px rgba(0,0,0,0.08);
  border-radius: 8px;
  padding: 8px 0;
  z-index: 1000;
}

.dropdown__menu.is-open{
  display: block;
}

.dropdown__item{
  display: block;
  padding: 10px 16px;
  text-decoration: none;
  color: #222;
  white-space: nowrap;
}

.dropdown__item:hover{
  background: #f5f5f5;
}