:root{
  --bg:#0b0e13; --panel:rgba(255,255,255,.06); --panel-strong:rgba(255,255,255,.12);
  --text:#e6e7eb; --muted:#9aa1ad; --radius:16px; --shadow:0 10px 40px rgba(0,0,0,.45);
  --gradient:
    radial-gradient(1200px 600px at 10% -10%, #0ea5e9 0%, transparent 50%),
    radial-gradient(1400px 800px at 100% 20%, #8b5cf6 0%, transparent 40%),
    radial-gradient(900px 700px at 40% 120%, #14b8a6 0%, transparent 50%),
    linear-gradient(180deg, #0b0e13 10%, #0b0e13 100%);
}

*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  background:var(--bg);
  color:var(--text);
  font-family:ui-sans-serif,system-ui,-apple-system,'Segoe UI',Roboto,Arial;
  overflow-x:hidden;
}

a{color:#a5f3fc}

/* ===== Header ===== */
.site-header{
  position:sticky;top:0;z-index:50;backdrop-filter:blur(10px);
  background:rgba(10,12,18,.6);border-bottom:1px solid rgba(255,255,255,.08);
  display:flex;align-items:center;justify-content:space-between;padding:10px 18px;
}
.brand{display:flex;align-items:center;gap:10px}
.logo{
  width:36px;height:36px;border-radius:8px;
  background:linear-gradient(135deg,#60a5fa,#a78bfa);
  display:flex;align-items:center;justify-content:center;
  box-shadow:var(--shadow)
}
.title{font-weight:700;letter-spacing:.5px}
.nav a{margin:0 10px;text-decoration:none;color:var(--text);opacity:.9}
.nav a:hover{opacity:1;color:#fff}

/* ===== Hero ===== */
.hero{
  position:relative;min-height:40vh;display:grid;place-items:center;text-align:center;overflow:hidden;
}
.hero-inner{position:relative;z-index:2;max-width:900px;padding:40px 18px}
.hero h1{font-size:clamp(32px,7vw,64px);line-height:1.05;margin:0 0 12px}
.hero p{color:var(--muted);font-size:clamp(16px,2vw,20px)}
.cta{display:flex;align-items:center;gap:10px;justify-content:center;margin-top:16px}
.btn{
  border:1px solid rgba(255,255,255,.15);background:var(--panel);color:var(--text);
  padding:10px 14px;border-radius:10px;cursor:pointer;box-shadow:var(--shadow);transition:.2s;
}
.btn:hover{transform:translateY(-1px);background:var(--panel-strong)}
.btn.primary{background:linear-gradient(135deg,#22d3ee,#8b5cf6);color:#0b0e13;border:none}
.btn.ghost{background:transparent}
.hero-bg{position:absolute;inset:0;background:var(--gradient);opacity:.9;filter:saturate(120%) blur(6px)}

@media (max-width: 768px) {
  .hero {
    min-height: 50vh; /* smaller hero on phones */
  }
}

.hero .cta {
  display: none;
}

.hero h1 {
  white-space: nowrap;
}

@media (max-width: 480px) {
  .hero h1 {
    font-size: clamp(24px, 7vw, 40px);
    white-space: nowrap;
  }
}


/* ===== Containers ===== */
.container{max-width:1200px;margin:0 auto;padding:24px}
.glass{
  background:linear-gradient(180deg,rgba(255,255,255,.06),rgba(255,255,255,.02));
  border:1px solid rgba(255,255,255,.08);
  border-radius:var(--radius);box-shadow:var(--shadow);
}
.glass-sub{
  background:linear-gradient(180deg,rgba(255,255,255,.04),rgba(255,255,255,.01));
  border:1px solid rgba(255,255,255,.06);border-radius:var(--radius);
  padding:14px;margin-top:10px;
}

/* ===== Playground Layout ===== */
/* === Desktop / Default === */
.playground {
  display: grid;
  grid-template-columns: 360px 1fr; /* controls left, canvas right */
  gap: 16px;
  align-items: start;
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
}

.controls {
  padding: 16px;
  width: 100%;
  box-sizing: border-box;
  order: 0; /* ✅ ensure correct order on desktop */
}

.stage {
  order: 0; /* ✅ ensure correct order on desktop */
}

/* === Mobile === */
@media (max-width: 980px) {
  .playground {
    display: flex;
    flex-direction: column;
    max-width: 100%;
    padding: 1rem;
  }

  .stage {
    order: 1;
    width: 100%;
  }

  .controls {
    order: 2;
    width: 100%;
  }
}

.controls h2{margin-top:4px}
.row{display:flex;align-items:center;justify-content:space-between;gap:10px;margin:12px 0}
.row input[type='range']{width:170px}
.switch{position:relative;display:inline-block;width:48px;height:28px}
.switch input{display:none}
.slider{position:absolute;inset:0;background:#444b57;border-radius:999px;transition:.2s}
.slider:before{content:'';position:absolute;height:22px;width:22px;left:3px;top:3px;background:#d1d5db;border-radius:50%;transition:.2s}
.switch input:checked + .slider{background:linear-gradient(135deg,#22d3ee,#8b5cf6)}
.switch input:checked + .slider:before{transform:translateX(20px);background:#fff}
.hint{color:var(--muted);font-size:13px;margin-top:8px}
.buttons{display:flex;flex-wrap:wrap;gap:8px;margin-top:6px}

/* === Presets: keep in one line and scrollable if needed === */
.row.presets {
  display:flex;
  flex-wrap:nowrap;
  align-items:center;
  justify-content:flex-start;
  gap:8px;
  overflow-x:auto;
  -webkit-overflow-scrolling:touch;
  scrollbar-width:none;
}
.row.presets::-webkit-scrollbar {display:none;}
.row.presets span {flex:0 0 auto;white-space:nowrap;font-weight:500;}
.row.presets .chip {
  flex:0 0 auto;
  display:inline-flex;
  align-items:center;
  justify-content:center;
  padding:6px 14px;
  font-size:15px;
  border:1px solid rgba(255,255,255,.15);
  background:rgba(255,255,255,.06);
  color:var(--text);
  border-radius:999px;
  cursor:pointer;
  transition:.2s;
  white-space:nowrap;
}
.row.presets .chip:hover{background:rgba(255,255,255,.12)}
@media(max-width:480px){.row.presets{justify-content:center;}}

/* === Stage / Canvas === */
.stage{
  position:relative;
  display:flex;
  justify-content:center;
  align-items:center;
  padding:12px;
  width:100%;
  box-sizing:border-box;
}
.stage-inner{
  width:100%;
  max-width:900px;
  position:relative;
}
#kaleido{
  width:100%;
  height:auto;
  aspect-ratio:1/1;
  display:block;
  border-radius:14px;
  border:1px solid rgba(255,255,255,.08);
  box-shadow:0 10px 40px rgba(0,0,0,.45);
  background:#080a0f;
}
.badge{
  position:absolute;
  bottom:14px;right:18px;
  font-size:14px;
  padding:6px 10px;
  background:rgba(0,0,0,.5);
  border:1px solid rgba(255,255,255,.1);
  border-radius:999px;
}

/* ===== Math & Gallery ===== */
.math-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:14px}
.info-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:14px}
.card{padding:16px;border-radius:12px;background:rgba(255,255,255,.06);border:1px solid rgba(255,255,255,.08)}
.formula{font-family:ui-monospace,Menlo,Consolas,monospace;border:1px solid rgba(255,255,255,.12);padding:2px 6px;border-radius:6px}
.calc{margin-top:10px}
.calc-grid{display:grid;grid-template-columns:280px 1fr;gap:14px;align-items:start}
.calc-card input{width:100%;padding:8px;border-radius:8px;border:1px solid rgba(255,255,255,.18);background:rgba(255,255,255,.04);color:var(--text)}
.calc-out{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:8px;padding:8px;background:rgba(0,0,0,.25);border:1px solid rgba(255,255,255,.08);border-radius:12px}
.small{color:var(--muted);font-size:13px}
.gallery{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:12px}
.gallery img{width:100%;border-radius:12px;cursor:pointer;border:1px solid rgba(255,255,255,.08);transition:.2s;background:#0a0d12}
.gallery img:hover{transform:translateY(-2px)}
.site-footer{display:flex;align-items:center;justify-content:center;padding:22px;color:var(--muted)}

/* ===== Responsive for Mobile / Tablet ===== */
@media (max-width:980px){
  .playground{
    display:flex;
    flex-direction:column;
    gap:24px;
    padding:1rem;
    width:100%;
  }
  .controls{
    order:2;
    width:100%;
  }
  .stage{
    order:1;
    width:100%;
  }
  .row{
    flex-direction:column;
    align-items:flex-start;
    gap:.5rem;
    width:100%;
  }
  .row input[type='range']{width:100%}
  .buttons{flex-wrap:wrap}
  .btn{flex:1;min-width:100px}
  .calc-grid{grid-template-columns:1fr}
  #kaleido{max-width:100%;height:auto}
}

/* ===== Mobile Menu ===== */
.menu-toggle{display:none;flex-direction:column;cursor:pointer;gap:6px}
.bar{width:28px;height:4px;border-radius:4px;background:linear-gradient(135deg,#22d3ee,#8b5cf6);transition:all .4s ease}
.menu-open .bar:nth-child(1){transform:rotate(45deg) translate(6px,6px)}
.menu-open .bar:nth-child(2){opacity:0}
.menu-open .bar:nth-child(3){transform:rotate(-45deg) translate(6px,-6px)}
.nav-overlay{position:fixed;inset:0;display:none;justify-content:center;align-items:center;background:var(--gradient);backdrop-filter:blur(16px);animation:fadeIn .6s ease forwards;z-index:99}
.nav-overlay.active{display:flex}
.overlay-content{display:flex;flex-direction:column;text-align:center;gap:24px}
.overlay-content a{color:var(--text);text-decoration:none;font-size:2rem;transition:color .3s,text-shadow .3s,transform .3s}
.overlay-content a:hover{color:#fff;text-shadow:0 0 10px #8b5cf6;transform:scale(1.05)}
@keyframes fadeIn{from{opacity:0;transform:scale(1.05)}to{opacity:1;transform:scale(1)}}
@media(max-width:900px){.nav{display:none}.menu-toggle{display:flex}}