/* style.css — estilos básicos e responsivos (mobile-first) */
:root{
  --bg: #0f1724;
  --card: #0b1220;
  --accent: #4f46e5;
  --muted: #94a3b8;
  --glass: rgba(255,255,255,0.03);
  --success: #10b981;
}
*{box-sizing:border-box}
html,body{height:100%;margin:0;font-family:Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;color:#e6eef8;background:linear-gradient(180deg,#071020 0%, #0f1724 100%);}
.container{max-width:1100px;margin:0 auto;padding:20px}
.screen{padding:20px}
.hidden{display:none}
.title{font-size:1.8rem;margin:8px 0}
.subtitle{color:var(--muted);margin-bottom:18px}
.btn{appearance:none;border:0;padding:10px 14px;border-radius:8px;cursor:pointer;font-weight:600}
.btn.primary{background:linear-gradient(90deg,var(--accent),#7c3aed);color:white}
.btn.link{background:none;color:var(--muted);padding:6px}
.categories{margin-top:24px;background:var(--glass);padding:12px;border-radius:10px}
.categories ul{padding-left:16px;margin:6px 0;color:var(--muted)}
.formula-card{margin-top:18px;background:rgba(255,255,255,0.03);padding:16px;border-radius:12px}
.formula-highlight{font-size:1.4rem;font-weight:700;color:var(--accent);margin-bottom:8px}
.formula-card .left-column{margin-bottom:18px}
.variaveis{display:flex;flex-wrap:wrap;gap:12px;margin:8px 0}
.var-item{display:flex;flex-direction:column;gap:6px}
.var-item label{font-size:0.9rem;color:var(--muted)}
.var-item input{padding:10px;border-radius:8px;border:1px solid rgba(255,255,255,0.06);background:transparent;color:inherit;width:140px}
.var-controls{display:flex;flex-direction:column;gap:8px}
.range-input{width:100%;margin-top:6px}
.presets{display:flex;gap:8px;margin-top:6px}
.preset-btn{background:transparent;border:1px solid rgba(255,255,255,0.06);padding:6px 8px;border-radius:8px;color:var(--muted);cursor:pointer}
.actions{margin-top:10px}
.resultado{margin-top:14px;background:rgba(255,255,255,0.02);padding:10px;border-radius:8px}
.resultado-valor{font-size:1.2rem;font-weight:700;margin-top:6px}
.resultado-explicacao{color:var(--muted);margin-top:6px}
.visualizacao{margin-top:14px}
canvas{width:100%;height:auto;border-radius:8px;background:linear-gradient(180deg,rgba(255,255,255,0.01),transparent);display:block}
.visual-info{display:flex;gap:16px;color:var(--muted);margin-top:8px}
.game-header{display:flex;align-items:center;gap:12px}
.select-wrap{margin-left:auto}
select#select-formula{background:transparent;border-radius:8px;padding:8px 10px;border:1px solid rgba(255,255,255,0.06);color:inherit}
.visually-hidden{position:absolute!important;height:1px;width:1px;overflow:hidden;clip:rect(1px,1px,1px,1px)}
.desafio{margin-top:12px;background:rgba(255,255,255,0.02);padding:10px;border-radius:8px}
.desafio-controls{display:flex;flex-direction:column;gap:8px}
.desafio-enunciado{color:var(--muted)}
.desafio-feedback{margin-top:6px}
.desafio-progresso{color:var(--muted);font-size:0.9rem;margin-top:6px}
.visual-controls{display:flex;align-items:center;gap:8px;margin-top:8px}
#zoom-range{width:120px}
.right-column{margin-top:18px}
@media(min-width:700px){
  .title{font-size:2.4rem}
  .formula-card{display:grid;grid-template-columns:1fr 420px;gap:18px}
  canvas{height:300px}
  .right-column{margin-top:0}
}
.error{color:#ff6b6b;font-size:0.9rem;margin-top:6px}
.footer-note{color:var(--muted);font-size:0.9rem;margin-top:12px}
@media(max-width:480px){
  html,body{max-width:100%;overflow-x:hidden}
  .container,.screen{width:100%;max-width:100%;padding:12px}
  .game-header,.visual-info,.presets,.visual-controls{flex-wrap:wrap}
  .var-item,.var-item input{max-width:100%}
}