:root{
  --bg:#0f1420; --panel:#171d2b; --panel-2:#1e2636; --border:#2a3346;
  --text:#e8edf5; --muted:#9aa7bd; --brand:#4f8cff; --brand-2:#7c5cff;
  --ok:#2ecc71; --bad:#ff5c6c; --code:#0b0f18; --shadow:0 6px 24px rgba(0,0,0,.35);
  --radius:12px;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  background:linear-gradient(180deg,#0c111b,#0f1420 240px);
  color:var(--text); font:15px/1.6 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"PingFang SC","Microsoft YaHei",sans-serif;
  min-height:100vh;
}
a{color:var(--brand);text-decoration:none}
a:hover{text-decoration:underline}
.wrap{max-width:960px;margin:0 auto;padding:0 16px 64px}
.tools-topbar{
  position:sticky;top:0;z-index:50;display:flex;align-items:center;gap:12px;
  padding:10px 16px;background:rgba(15,20,32,.85);backdrop-filter:blur(8px);
  border-bottom:1px solid var(--border);
}
.tools-topbar .brand{font-weight:700;color:var(--text);font-size:15px}
.tools-topbar .brand span{background:linear-gradient(90deg,var(--brand),var(--brand-2));-webkit-background-clip:text;background-clip:text;color:transparent}
.tools-topbar .spacer{flex:1}
.lang-switch{display:flex;gap:4px;flex-wrap:wrap}
.lang-switch button{
  background:var(--panel-2);color:var(--muted);border:1px solid var(--border);
  border-radius:999px;padding:4px 10px;font-size:12px;cursor:pointer;transition:.15s;
}
.lang-switch button:hover{color:var(--text)}
.lang-switch button.active{background:linear-gradient(90deg,var(--brand),var(--brand-2));color:#fff;border-color:transparent}
.home-link{color:var(--muted);font-size:13px}
.hero{padding:36px 0 18px;text-align:center}
.hero h1{font-size:28px;margin:0 0 8px;background:linear-gradient(90deg,var(--brand),var(--brand-2));-webkit-background-clip:text;background-clip:text;color:transparent}
.hero p{color:var(--muted);margin:0 auto;max-width:640px}
.card{background:var(--panel);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);padding:20px;margin:18px 0}
.card h2{margin:0 0 4px;font-size:18px}
.card .sub{color:var(--muted);font-size:13px;margin:0 0 16px}
.row{display:flex;gap:10px;flex-wrap:wrap;align-items:center;margin-bottom:12px}
.row.tight{margin-bottom:6px}
label.lbl{display:block;color:var(--muted);font-size:13px;margin:0 0 6px}
textarea,input[type=text],input[type=number],select{
  width:100%;background:var(--code);color:var(--text);border:1px solid var(--border);
  border-radius:10px;padding:12px;font-size:14px;font-family:"SF Mono",ui-monospace,Menlo,Consolas,monospace;
  resize:vertical;
}
textarea{min-height:200px}
input:focus,textarea:focus,select:focus{outline:none;border-color:var(--brand)}
button.btn{
  background:linear-gradient(90deg,var(--brand),var(--brand-2));color:#fff;border:none;
  border-radius:10px;padding:10px 16px;font-size:14px;font-weight:600;cursor:pointer;transition:.15s;
}
button.btn:hover{filter:brightness(1.08)}
button.btn.ghost{background:var(--panel-2);color:var(--text);border:1px solid var(--border)}
button.btn.sm{padding:6px 12px;font-size:13px}
.grid2{display:grid;grid-template-columns:1fr 1fr;gap:16px}
@media(max-width:720px){.grid2{grid-template-columns:1fr}}
.out{
  background:var(--code);border:1px solid var(--border);border-radius:10px;padding:12px;
  min-height:80px;white-space:pre-wrap;word-break:break-all;font-family:ui-monospace,Menlo,Consolas,monospace;font-size:13px;
}
.out.ok{border-color:var(--ok)} .out.bad{border-color:var(--bad);color:var(--bad)}
.tag{display:inline-block;background:var(--panel-2);border:1px solid var(--border);color:var(--muted);border-radius:6px;padding:2px 8px;font-size:12px;margin:2px}
.tutorial{color:var(--muted);font-size:13px;border-left:3px solid var(--brand);padding:8px 14px;margin-top:14px;background:var(--panel-2);border-radius:0 8px 8px 0}
.toast{
  position:fixed;bottom:24px;left:50%;transform:translateX(-50%) translateY(20px);
  background:var(--ok);color:#04210f;padding:10px 18px;border-radius:999px;font-weight:600;
  opacity:0;pointer-events:none;transition:.25s;z-index:99;
}
.toast.show{opacity:1;transform:translateX(-50%) translateY(0)}
.tile-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:14px;margin-top:18px}
.tile{display:block;background:var(--panel);border:1px solid var(--border);border-radius:var(--radius);padding:16px;transition:.15s}
.tile:hover{border-color:var(--brand);text-decoration:none;transform:translateY(-2px)}
.tile h3{margin:0 0 6px;font-size:16px;color:var(--text)}
.tile p{margin:0;color:var(--muted);font-size:13px}
.cat-title{margin:28px 0 4px;font-size:15px;color:var(--brand);font-weight:700}
[dir=rtl] .tutorial{border-left:none;border-right:3px solid var(--brand);border-radius:8px 0 0 8px}
[dir=rtl] .tools-topbar .spacer{order:0}
.muted{color:var(--muted)}
.ctl{display:flex;flex-direction:column;gap:4px;font-size:13px;color:var(--muted);flex:1;min-width:140px}
.ctl select,.ctl input{width:100%}
.kv-grid{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin-top:8px}
.kv{display:flex;flex-direction:column;gap:4px}
.kv .k{color:var(--muted);font-size:12px}
.kv .out{min-height:auto;font-size:13px}
@media(max-width:720px){.kv-grid{grid-template-columns:1fr}}
.tree{background:var(--code);border:1px solid var(--border);border-radius:10px;padding:12px;font-family:ui-monospace,Menlo,Consolas,monospace;font-size:13px;max-height:480px;overflow:auto;white-space:normal}
.tnode{margin-left:14px}
.trow{display:flex;align-items:baseline;gap:6px;padding:1px 0}
.tog{color:var(--brand);cursor:pointer;width:14px;display:inline-block;text-align:center;user-select:none}
.tog.leaf{color:var(--muted);cursor:default}
.tkey{color:var(--brand)}
.tval.tobj{color:var(--muted)}
.tval.tprimitive{color:var(--ok)}
.hl{background:rgba(79,140,255,.28);border-radius:3px;padding:0 2px}
[dir=rtl] .tnode{margin-left:0;margin-right:14px}
/* Text diff */
.diff-add{background:rgba(46,204,113,.18);color:#4dff95;border-radius:3px;padding:0 1px}
.diff-del{background:rgba(255,92,108,.18);color:#ff8090;border-radius:3px;padding:0 1px;text-decoration:line-through;text-decoration-color:rgba(255,92,108,.4)}
.diff-eq{color:var(--muted)}
/* Color picker */
.palette-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(80px,1fr));gap:10px}
.swatch{height:56px;border-radius:10px;border:1px solid var(--border);display:flex;align-items:flex-end;justify-content:center;padding:4px;font-size:10px;color:#fff;text-shadow:0 1px 3px rgba(0,0,0,.7);cursor:pointer;transition:.15s;user-select:none}
.swatch:hover{transform:scale(1.05);border-color:var(--brand)}
input[type=color]{border-radius:8px;cursor:pointer}