/* ============================================================
     共通スタイル：色の変数、背景（霧・熾火）、画面の枠組み、共通ボタン、フッター、PC表示
     ============================================================ */
  :root{
    --bg-void:#08070a;
    --bg-panel:#120e14;
    --bg-panel-2:#1a1420;
    --blood:#8b1a2b;
    --blood-bright:#c92a3d;
    --ash-purple:#3d1a4a;
    --ash-purple-2:#5c2a6e;
    --bone:#e9e2d3;
    --bone-dim:#a89a8a;
    --sick-green:#4a7c59;
    --sick-green-bright:#6fbf7f;
    --line:#2a2028;
    --shadow-deep: 0 20px 60px rgba(0,0,0,0.7);
  }

  *{box-sizing:border-box;-webkit-tap-highlight-color:transparent;}

  html,body{
    margin:0;padding:0;height:100%;
    background:var(--bg-void);
    color:var(--bone);
    font-family:'Zen Kaku Gothic New',sans-serif;
    overscroll-behavior:none;
  }

  #app{
    position:relative;
    min-height:100vh;
    min-height:100dvh;
    display:flex;
    flex-direction:column;
    overflow:hidden;
  }

  /* ---------- 背景演出：漂う霧・熾火 ---------- */
  .fog-layer{
    position:fixed;inset:-10% -10%;
    pointer-events:none;
    z-index:0;
    background:
      radial-gradient(ellipse 60% 40% at 20% 15%, rgba(61,26,74,0.35), transparent 60%),
      radial-gradient(ellipse 50% 35% at 85% 80%, rgba(139,26,43,0.22), transparent 60%),
      radial-gradient(ellipse 70% 50% at 50% 100%, rgba(92,42,110,0.18), transparent 65%);
    animation: driftFog 22s ease-in-out infinite alternate;
  }
  @keyframes driftFog{
    0%{ transform: translate(0,0) scale(1); }
    100%{ transform: translate(-2%,3%) scale(1.05); }
  }
  .embers{
    position:fixed;inset:0;pointer-events:none;z-index:0;overflow:hidden;
  }
  .ember{
    position:absolute;bottom:-10px;
    width:3px;height:3px;border-radius:50%;
    background:var(--blood-bright);
    box-shadow:0 0 6px 1px rgba(201,42,61,0.8);
    opacity:0;
    animation-name:emberRise;
    animation-timing-function:linear;
    animation-iteration-count:infinite;
  }
  @keyframes emberRise{
    0%{ transform:translateY(0) translateX(0); opacity:0; }
    8%{ opacity:0.9; }
    90%{ opacity:0.3; }
    100%{ transform:translateY(-110vh) translateX(20px); opacity:0; }
  }

  @media (prefers-reduced-motion: reduce){
    .fog-layer, .ember{ animation:none !important; }
  }

  main{
    position:relative;z-index:1;
    flex:1;
    display:flex;
    flex-direction:column;
    max-width:560px;
    width:100%;
    margin:0 auto;
    padding:20px 18px calc(24px + env(safe-area-inset-bottom));
  }

  .screen{ display:none; flex-direction:column; flex:1; animation:fadeIn .5s ease; }
  .screen.active{ display:flex; }
  /* その場でふわっと現れる（透明度だけを変える）。
     位置をずらすと、margin では高さが一瞬増えてスクロールバーが出て、transform では
     「タイトルへ戻る」リンクの位置の基準が変わって跳ねてしまうため、動きは付けない */
  @keyframes fadeIn{ from{opacity:0;} to{opacity:1;} }

  /* ---------- 共通アイコンボタン（音声・ホーム等） ---------- */
  .icon-btn{
    background:none;border:1px solid var(--line);color:var(--bone-dim);
    width:38px;height:38px;border-radius:100px;font-size:16px;cursor:pointer;flex-shrink:0;
    display:flex;align-items:center;justify-content:center;
    transition:border-color .15s ease, color .15s ease, transform .1s ease;
  }
  .icon-btn:active{ transform:scale(0.92); }

  .sound-control{
    position:absolute;
    top:calc(14px + env(safe-area-inset-top));
    right:14px;
    z-index:15;
    display:flex;
    align-items:center;
    gap:8px;
  }
  .bgm-label{
    font-size:11px;
    letter-spacing:.08em;
    color:var(--bone-dim);
  }
  .global-sound-btn{
    background:rgba(18,14,20,0.7);
    backdrop-filter:blur(4px);
  }

  /* ---------- 共通ボタン ---------- */
  .btn-start{
    font-family:'Yuji Syuku',serif;
    font-size:17px;
    letter-spacing:.12em;
    padding:16px 44px;
    min-height:56px;
    background:linear-gradient(180deg, #2a1420, #1a0d14);
    border:1px solid var(--blood);
    color:var(--bone);
    border-radius:4px;
    box-shadow:0 0 0 1px rgba(139,26,43,0.15) inset, 0 10px 30px rgba(139,26,43,0.25);
    cursor:pointer;
    transition:transform .12s ease, box-shadow .2s ease;
  }
  .btn-start:active{ transform:scale(0.96); }

  .btn-secondary{
    min-height:50px;
    background:var(--bg-panel);
    border:1px solid var(--line);
    color:var(--bone-dim);
    border-radius:6px; font-size:14px; cursor:pointer;
  }

  /* 「タイトルへ戻る」リンク */
  .link-back{
    margin-top:18px; text-align:center;
    font-size:13px; color:var(--bone-dim);
    background:none;border:none;cursor:pointer;padding:10px;
    text-decoration:underline;text-underline-offset:3px;
  }
  .link-back-corner{
    position:absolute;
    top:0; left:0;
    margin-top:0;
    text-align:left;
    z-index:5;
  }

  /* ---------- フッター ---------- */
  footer.credit{
    position:relative;z-index:1;
    text-align:center; font-size:10.5px; color:var(--bone-dim);
    padding:0px 0 25px;
  }

  /* ---------- PC(デスクトップ)：ウィンドウ中央にアプリを配置 ---------- */
  @media (min-width:720px){
    html,body{
      display:flex;
      align-items:center;
      justify-content:center;
      background:radial-gradient(ellipse 80% 60% at 50% 40%, #150f18, #050408 70%);
    }
    #app{
      width:480px;
      max-width:480px;
      height:min(880px, 94vh);
      min-height:auto;
      border-radius:20px;
      border:1px solid var(--line);
      box-shadow:var(--shadow-deep), 0 0 0 1px rgba(139,26,43,0.08);
      overflow-y:auto;
      overflow-x:hidden;
    }
  }