:root{
  /* 黒板を思わせる落ち着いた配色 */
  --board:#16241f;
  --board2:#1d2f28;
  --panel:#21332c;
  --panel2:#273b33;
  --line:#3c5b4e;
  --chalk:#eef4ef;
  --chalk-dim:#b6c9bf;
  --chalk-faint:#8ba49a;
  --accent:#ffd978;      /* 見出し・強調（チョークの黄） */
  --accent2:#9adcc0;     /* 副強調 */

  /* 現象の色（凡例と一致させる） */
  --quake:#ff4d4d;       /* 地震：赤 */
  --volcano:#ff8c1a;     /* 火山：オレンジ */
  --mountain:#a9702f;    /* 山脈：茶 */
  --trench:#2f7fd6;      /* 海溝：青 */
  --ridge:#46c6a8;       /* 中央海嶺：緑青 */
  --fault:#e8d44d;       /* 断層：黄 */

  /* プレートの色 */
  --oceanic:#3b6b8f;
  --oceanic2:#2b5270;
  --contin:#7d6a4f;
  --contin2:#5f5039;

  --fs:16px;
  --radius:12px;
  --safe-l:env(safe-area-inset-left,0px);
  --safe-r:env(safe-area-inset-right,0px);
  --safe-b:env(safe-area-inset-bottom,0px);
}
*{box-sizing:border-box}
html{font-size:var(--fs);-webkit-text-size-adjust:100%}
body{
  margin:0;background:var(--board);color:var(--chalk);
  font-family:"Hiragino Sans","Hiragino Kaku Gothic ProN","Yu Gothic",YuGothic,"Noto Sans JP",Meiryo,system-ui,sans-serif;
  line-height:1.7;-webkit-tap-highlight-color:transparent;
}
body::before{
  content:"";position:fixed;inset:0;pointer-events:none;z-index:0;opacity:.5;
  background:
    radial-gradient(circle at 15% 10%,rgba(255,255,255,.045),transparent 42%),
    radial-gradient(circle at 85% 85%,rgba(255,255,255,.03),transparent 45%);
}
#app{position:relative;z-index:1}
h1,h2,h3{line-height:1.35;margin:0}
button{font:inherit;color:inherit}

.wrap{max-width:1500px;margin:0 auto;padding:0 calc(14px + var(--safe-r)) calc(18px + var(--safe-b)) calc(14px + var(--safe-l))}

/* ===== ヘッダー ===== */
header.top{border-bottom:2px solid var(--line);background:linear-gradient(180deg,var(--board2),var(--board))}
header.top .inner{display:flex;align-items:center;gap:.9rem;flex-wrap:wrap;padding:.7rem 0}
.logo{
  width:46px;height:46px;flex:none;border-radius:10px;border:2px solid var(--accent);
  display:grid;place-items:center;background:rgba(255,217,120,.08)
}
.logo svg{width:30px;height:30px}
.htxt h1{font-size:1.25rem;letter-spacing:.04em;color:var(--accent)}
.htxt p{margin:.1rem 0 0;font-size:.82rem;color:var(--chalk-dim)}
.badge{
  margin-left:auto;font-size:.76rem;color:#2a2110;background:var(--accent);
  border-radius:999px;padding:.25rem .75rem;font-weight:700;letter-spacing:.02em
}

/* ===== レイアウト ===== */
.grid{display:grid;gap:14px;padding-top:14px;grid-template-columns:1fr}
@media (min-width:1080px){
  .grid{grid-template-columns:minmax(0,1.62fr) minmax(330px,1fr);align-items:start}
  .grid .full{grid-column:1/-1}
}

.card{
  background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);
  padding:.9rem 1rem;box-shadow:0 2px 10px rgba(0,0,0,.28)
}
.card > h2{
  font-size:1rem;color:var(--accent);letter-spacing:.05em;display:flex;align-items:center;gap:.5rem;
  margin-bottom:.55rem
}
.card > h2::before{content:"";width:.34rem;height:1.05rem;background:var(--accent);border-radius:2px;flex:none}
.card h3{font-size:.92rem;color:var(--accent2);margin:.85rem 0 .3rem}
.muted{color:var(--chalk-dim);font-size:.86rem}
.tiny{color:var(--chalk-faint);font-size:.78rem}

/* ===== 境界タイプ選択 ===== */
.types{display:grid;gap:.5rem;grid-template-columns:repeat(2,minmax(0,1fr))}
@media (min-width:760px){.types{grid-template-columns:repeat(4,minmax(0,1fr))}}
.type{
  -webkit-appearance:none;appearance:none;cursor:pointer;text-align:left;
  background:var(--panel2);border:2px solid var(--line);border-radius:10px;
  padding:.6rem .65rem;min-height:74px;display:flex;flex-direction:column;gap:.15rem;
  transition:border-color .15s,background .15s,transform .08s
}
.type:active{transform:scale(.985)}
.type .tn{font-weight:700;font-size:.93rem;line-height:1.3}
.type .td{font-size:.74rem;color:var(--chalk-faint);line-height:1.4}
.type .ti{font-size:1.1rem;letter-spacing:.1em;color:var(--chalk-dim)}
.type[aria-pressed="true"]{border-color:var(--accent);background:rgba(255,217,120,.14)}
.type[aria-pressed="true"] .td{color:var(--chalk-dim)}
.type:focus-visible{outline:3px solid var(--accent2);outline-offset:2px}

/* ===== 図 ===== */
.viewhead{display:flex;align-items:center;gap:.5rem;flex-wrap:wrap;margin-bottom:.5rem}
.viewhead h2{margin:0}
.timein{display:flex;align-items:center;gap:.4rem;margin:.35rem 0 .1rem}
.timein span,.timein .btn{white-space:nowrap}
.timein .btn{padding:.35rem .6rem}
.timein input{width:5.5em;min-width:0;font:inherit;font-size:1rem;padding:.3rem .45rem;border-radius:8px;border:1px solid var(--line);background:var(--board2);color:inherit;text-align:right}
.seg{display:flex;gap:.3rem;margin-left:auto;background:var(--board2);border:1px solid var(--line);border-radius:999px;padding:.2rem}
.seg button{
  -webkit-appearance:none;appearance:none;cursor:pointer;background:transparent;border:0;
  border-radius:999px;padding:.5rem .9rem;min-height:44px;font-size:.86rem;white-space:nowrap
}
.seg button[aria-pressed="true"]{background:var(--accent);color:#2a2110;font-weight:700}
.canvaswrap{position:relative;border:1px solid var(--line);border-radius:10px;overflow:hidden;background:#0e1a16}
canvas{display:block;width:100%;height:auto;touch-action:pan-y}
.viewnote{
  position:absolute;left:.55rem;bottom:.5rem;font-size:.74rem;color:var(--chalk-faint);
  background:rgba(14,26,22,.78);border:1px solid var(--line);border-radius:6px;padding:.15rem .45rem;pointer-events:none
}
.stagehint{
  position:absolute;right:.55rem;top:.5rem;font-size:.76rem;color:var(--chalk);
  background:rgba(14,26,22,.88);border:1px solid var(--line);border-radius:6px;padding:.2rem .5rem;pointer-events:none;
  max-width:52%;text-align:right;line-height:1.4
}
/* 狭い画面では図を広く使うため、ふきだしは図の下に出す */
@media (max-width:620px){
  .stagehint{position:static;max-width:100%;text-align:left;margin-top:.45rem;display:block;font-size:.8rem}
  .canvaswrap{overflow:visible;border:0;background:transparent}
  .canvaswrap canvas{border:1px solid var(--line);border-radius:10px;background:#0e1a16}
  .viewnote{position:static;margin-top:.35rem;display:inline-block}
}

/* ===== 操作パネル ===== */
.ctrls{display:grid;gap:.75rem}
@media (min-width:620px){.ctrls{grid-template-columns:1fr 1fr}}
.field label{display:block;font-size:.85rem;font-weight:700;margin-bottom:.15rem}
.field .val{color:var(--accent);font-variant-numeric:tabular-nums}
input[type=range]{
  -webkit-appearance:none;appearance:none;width:100%;height:44px;background:transparent;margin:0;cursor:pointer
}
input[type=range]::-webkit-slider-runnable-track{height:8px;border-radius:99px;background:var(--line)}
input[type=range]::-webkit-slider-thumb{
  -webkit-appearance:none;width:28px;height:28px;border-radius:50%;background:var(--accent);
  border:2px solid #2a2110;margin-top:-10px
}
input[type=range]::-moz-range-track{height:8px;border-radius:99px;background:var(--line)}
input[type=range]::-moz-range-thumb{width:24px;height:24px;border-radius:50%;background:var(--accent);border:2px solid #2a2110}
input[type=range]:focus-visible{outline:3px solid var(--accent2);outline-offset:4px;border-radius:8px}
.btns{display:flex;gap:.45rem;flex-wrap:wrap}
.btn{
  -webkit-appearance:none;appearance:none;cursor:pointer;background:var(--panel2);
  border:1px solid var(--line);border-radius:10px;padding:.55rem .95rem;min-height:46px;
  display:inline-flex;align-items:center;gap:.35rem;font-weight:600
}
.btn:active{transform:scale(.97)}
.btn-main{background:var(--accent);color:#2a2110;border-color:var(--accent)}
.btn:focus-visible{outline:3px solid var(--accent2);outline-offset:2px}
.plateinfo{display:grid;gap:.4rem;margin-top:.2rem}
.pi{display:flex;align-items:center;gap:.5rem;font-size:.86rem;background:var(--board2);border:1px solid var(--line);border-radius:8px;padding:.35rem .5rem}
.sw{width:1.5rem;height:.85rem;border-radius:3px;flex:none;border:1px solid rgba(255,255,255,.25)}
.pi .dir{margin-left:auto;color:var(--accent2);font-weight:700;white-space:nowrap}

/* ===== 凡例 ===== */
.legend{display:grid;gap:.4rem;grid-template-columns:repeat(2,minmax(0,1fr))}
@media (min-width:520px){.legend{grid-template-columns:repeat(3,minmax(0,1fr))}}
@media (min-width:1080px){.legend{grid-template-columns:repeat(2,minmax(0,1fr))}}
.lg{display:flex;align-items:center;gap:.45rem;font-size:.84rem}
.lg .ic{width:1.45rem;height:1.45rem;flex:none;display:grid;place-items:center}
.lg .ic svg{width:100%;height:100%}
.lg.off{opacity:.38}
.lg.off .nm::after{content:"（この境界では見られない）";font-size:.7rem;color:var(--chalk-faint)}

/* ===== 説明・まとめ ===== */
.why{background:var(--board2);border-left:4px solid var(--accent2);border-radius:8px;padding:.6rem .75rem;margin-top:.5rem}
.why dt{font-weight:700;color:var(--accent2);font-size:.88rem;margin-top:.5rem}
.why dt:first-child{margin-top:0}
.why dd{margin:.1rem 0 0;font-size:.9rem}
.sumlist{list-style:none;margin:.2rem 0 0;padding:0;display:grid;gap:.4rem}
.sumlist li{display:flex;gap:.5rem;align-items:flex-start;background:var(--board2);border:1px solid var(--line);border-radius:8px;padding:.4rem .55rem;font-size:.88rem}
.sumlist .ic{width:1.35rem;height:1.35rem;flex:none;margin-top:.12rem}
.sumlist .ic svg{width:100%;height:100%}
.sumlist .k{font-weight:700;margin-right:.3rem}
.sumlist.none li{opacity:.55}
.readout{display:grid;gap:.35rem;grid-template-columns:repeat(2,minmax(0,1fr));margin-top:.55rem}
.ro{background:var(--board2);border:1px solid var(--line);border-radius:8px;padding:.35rem .5rem}
.ro .k{font-size:.72rem;color:var(--chalk-faint)}
.ro .v{font-size:1.05rem;font-weight:700;color:var(--accent);font-variant-numeric:tabular-nums}

/* ===== 考えてみよう ===== */
.qcards{display:grid;gap:.6rem}
@media (min-width:760px){.qcards{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media (min-width:1080px){.qcards{grid-template-columns:1fr}}
@media (min-width:1400px){.qcards{grid-template-columns:repeat(2,minmax(0,1fr))}}
.qc{background:var(--board2);border:1px solid var(--line);border-left:4px solid var(--accent);border-radius:8px;padding:.6rem .7rem}
.qc .qn{font-size:.72rem;color:var(--accent);font-weight:700;letter-spacing:.08em}
.qc .qq{font-size:.93rem;font-weight:600;margin:.15rem 0 .45rem}
.qc .qa{font-size:.88rem;color:var(--chalk-dim);display:none;border-top:1px dashed var(--line);padding-top:.4rem}
.qc.open .qa{display:block}
.qc .tog{
  -webkit-appearance:none;appearance:none;cursor:pointer;background:transparent;border:1px solid var(--line);
  border-radius:999px;padding:.4rem .85rem;min-height:44px;font-size:.82rem;color:var(--accent2)
}

/* ===== 注意書き ===== */
.notice{
  border:1px dashed var(--accent);border-radius:10px;background:rgba(255,217,120,.07);
  padding:.7rem .85rem;font-size:.86rem
}
.notice strong{color:var(--accent)}
footer.foot{margin-top:14px;text-align:center;font-size:.78rem;color:var(--chalk-faint)}

/* プロジェクター用に文字を大きくする */
html.big{--fs:19px}
html.big .type .td{font-size:.78rem}
@media (prefers-reduced-motion:reduce){*{animation-duration:.01ms!important;transition-duration:.01ms!important}}
.sr{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;border:0}

/* ===== 3D表示（3ラボ共通） ===== */
.v3d{position:relative;width:100%;background:#0e1a16;overflow:hidden;border-radius:10px}
.v3d canvas{display:block;width:100%!important;touch-action:none}
.v3dlabels{position:absolute;inset:0;pointer-events:none}
.v3dl{position:absolute;left:0;top:0;white-space:nowrap;font-size:.8rem;font-weight:700;line-height:1.3;
  padding:.1rem .4rem;border-radius:6px;background:rgba(14,26,22,.86);border:1px solid var(--line);color:var(--chalk)}
.v3dl.minor{font-weight:400;font-size:.72rem}
html.nolabels .v3dl{display:none}
.v3dhint{position:absolute;left:.55rem;bottom:.5rem;font-size:.72rem;color:var(--chalk-faint);background:rgba(14,26,22,.78);
  border:1px solid var(--line);border-radius:6px;padding:.1rem .45rem;pointer-events:none;z-index:2}
.v3dfail{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;text-align:center;padding:1rem;color:var(--chalk-dim)}
.canvaswrap.is3d > canvas,.canvaswrap.is3d > .stagehint{display:none}
.seg3d{margin-left:0}
.v3dctrl{display:flex;flex-wrap:wrap;gap:.45rem;align-items:center;margin-top:.5rem}
.v3dctrl[hidden]{display:none}
.v3dctrl .field{flex:1 1 220px}
.depthbar{display:flex;gap:.35rem;flex-wrap:wrap;font-size:.75rem;color:var(--chalk-dim)}
.depthbar i{display:inline-block;width:.8rem;height:.8rem;border-radius:50%;margin-right:.2rem;vertical-align:-.1rem}
.srcnote{font-size:.7rem;color:var(--chalk-faint);margin:.35rem 0 0}
.backlink{color:var(--accent2);font-size:.8rem;text-decoration:none;white-space:nowrap}
@media (max-width:620px){
  .viewhead .seg{flex-wrap:wrap;border-radius:14px;margin-left:0;max-width:100%}
  .viewhead .seg button{padding:.45rem .65rem}
}
.toggles{display:flex;flex-wrap:wrap;gap:.4rem}
.tg{
  -webkit-appearance:none;appearance:none;cursor:pointer;border:2px solid var(--line);background:var(--board2);
  border-radius:999px;padding:.4rem .8rem;min-height:44px;font-size:.85rem;display:inline-flex;align-items:center;gap:.4rem
}
.tg i{width:.9rem;height:.9rem;border-radius:50%;display:inline-block}
.tg[aria-pressed="false"]{opacity:.5}
.tg[aria-pressed="true"]{border-color:var(--accent)}
.seg[hidden]{display:none}