:root{
  /* School-friendly palette: navy primary, warm yellow accent, supportive green */
  --bg: #07142a; /* deep navy background */
  --panel: #0b2540; /* darker panel */
  --panel-2: #072033;
  --text: #eef6fb; /* soft off-white */
  --muted: #9fb0c8; /* muted slate-blue */
  --line: #1f3a5b;
  --brand: #0b3d91; /* school navy */
  --brand2: #f6c85f; /* warm school yellow */
  --warn: #f59e0b;
  --bad: #ef4444;
  --ok: #16a34a;

  --radius: 18px;
  --shadow: 0 10px 30px rgba(0,0,0,.35);
  --max: 1100px;
}

*{ box-sizing:border-box; }
html{ scroll-behavior:smooth; }
body{
  margin:0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji","Segoe UI Emoji";
  background: radial-gradient(1200px 700px at 20% -10%, rgba(11,61,145,.10), transparent 55%),
              radial-gradient(900px 500px at 95% 10%, rgba(246,200,95,.06), transparent 55%),
              var(--bg);
  color:var(--text);
  line-height:1.5;
}

a{ color:inherit; text-decoration:none; }
.container{
  width:min(var(--max), calc(100% - 32px));
  margin:0 auto;
}

.site-header{
  position:sticky;
  top:0;
  z-index:50;
  backdrop-filter: blur(10px);
  background: rgba(11,15,23,.72);
  border-bottom:1px solid rgba(36,48,66,.7);
}

.site-header .container{
  display:flex;
  align-items:center;
  justify-content:space-between;
  padding:14px 0;
  gap:16px;
}

.brand{
  display:flex;
  align-items:center;
  gap:10px;
  font-weight:700;
  letter-spacing:.2px;
}
.brand-dot{
  width:10px;height:10px;border-radius:50%;
  background: linear-gradient(135deg, var(--brand), var(--brand2));
  box-shadow: 0 0 0 4px rgba(96,165,250,.12);
}
.nav{
  display:flex;
  gap:14px;
  color:var(--muted);
  font-weight:600;
  font-size:14px;
}
.nav a{
  padding:8px 10px;
  border-radius:12px;
  border:1px solid transparent;
}
.nav a:hover{
  background: rgba(17,24,39,.7);
  border-color: rgba(36,48,66,.7);
  color:var(--text);
}

.hero{
  padding:100px 0 22px;
  height: 100vh;
}
.hero-grid{
  display:grid;
  grid-template-columns: 1.25fr .9fr;
  gap:18px;
  align-items:stretch;
}
h1{
  margin:0 0 64px;
  font-size: clamp(28px, 3.2vw, 44px);
  line-height:1.1;
}
.lead{
  margin:0 0 16px;
  color:#d1d5db;
  font-size: clamp(16px, 1.4vw, 18px);
}
.bullets{
  margin:0 0 18px;
  padding-left:18px;
  color:var(--muted);
}
.bullets li{ margin:6px 0; }
.cta-row{
  display:flex;
  gap:10px;
  flex-wrap:wrap;
  margin: 64px 0 8px;
}
.micro{ margin:0; color:var(--muted); font-size:13px; }

.section{
  background: var(--panel);
  padding:100px 0;
}
.section.alt{
  background: var(--panel-2);
  border-top: 1px solid rgba(36,48,66,.6);
  border-bottom: 1px solid rgba(36,48,66,.6);
}
.section-head{
  margin-bottom:16px;
}
.section-head h2{
  margin:0 0 8px;
  font-size: clamp(20px, 2.1vw, 28px);
}
.section-head p{
  margin:0;
  color:var(--muted);
  max-width: 70ch;
}

.grid-2{
  display:grid;
  grid-template-columns: 1fr 1fr;
  gap:16px;
}
.grid-3{
  display:grid;
  grid-template-columns: repeat(3, 1fr);
  gap:16px;
}
.grid-2-tight{
  display:grid;
  grid-template-columns: 1fr 1fr;
  gap:12px;
}

.card{
  background: linear-gradient(180deg, rgba(17,24,39,.92), rgba(15,23,42,.92));
  border: 1px solid rgba(36,48,66,.75);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding:16px;
}

.card-title{
  margin:0 0 6px;
  font-size:18px;
}
.card-sub{
  margin:0 0 12px;
  color:var(--muted);
}

.form{
  display:grid;
  gap:12px;
}
.field span{
  display:block;
  margin-bottom:6px;
  font-weight:650;
  font-size:14px;
  color:#d1d5db;
}
input{
  width:100%;
  background: rgba(11,15,23,.55);
  color:var(--text);
  border:1px solid rgba(36,48,66,.9);
  border-radius: 14px;
  padding:12px 12px;
  font-size:16px;
  outline:none;
}
input:focus{
  border-color: rgba(96,165,250,.9);
  box-shadow: 0 0 0 4px rgba(96,165,250,.18);
}
/* Hide native number input spinners so users enter via keyboard/touch */
input[type="number"]{
  -moz-appearance: textfield;
  appearance: textfield;
}
input[type="number"]::-webkit-outer-spin-button,
input[type="number"]::-webkit-inner-spin-button{
  -webkit-appearance: none;
  margin: 0;
}
::-webkit-calendar-picker-indicator {
    filter: invert(1) brightness(100%);
}

.row{
  display:flex;
  gap:10px;
  align-items:center;
  flex-wrap:wrap;
}

.btn{
  border:1px solid rgba(36,48,66,.9);
  border-radius: 14px;
  padding:10px 12px;
  background: rgba(17,24,39,.6);
  color: var(--text);
  font-weight:700;
  cursor:pointer;
}
.btn:hover{ filter: brightness(1.08); }
.btn.primary{
  border-color: rgba(96,165,250,.8);
  background: linear-gradient(135deg, #60a5fa40, #34d39924);
}
.btn.ghost{
  background: rgba(11,15,23,.35);
}

.chip{
  border:1px solid rgba(36,48,66,.9);
  background: rgba(11,15,23,.35);
  color: var(--text);
  border-radius: 999px;
  padding:9px 10px;
  cursor:pointer;
  font-weight:700;
}
.chip:hover{ border-color: rgba(96,165,250,.65); }

.form-hint{ margin:0; color:var(--muted); font-size:13px; }

.result{
  display:grid;
  gap:12px;
}
.result-main{
  display:flex;
  flex-direction:column;
  gap:6px;
}
.big{
  font-size:46px;
  font-weight:900;
  letter-spacing:-.8px;
  line-height:1;
}
.sub{ color:var(--muted); }

.result-grid{
  display:grid;
  grid-template-columns: 1fr 1fr;
  gap:12px;
}
.stat{
  background: rgba(11,15,23,.35);
  border:1px solid rgba(36,48,66,.7);
  border-radius: 16px;
  padding:12px;
}
.stat-label{ color:var(--muted); font-size:13px; }
.stat-value{ font-size:18px; font-weight:800; margin-top:3px; }

.details{
  background: rgba(11,15,23,.28);
  border:1px solid rgba(36,48,66,.6);
  border-radius: 16px;
  padding:10px 12px;
}
.details summary{
  cursor:pointer;
  font-weight:800;
}
.steps{
  margin-top:10px;
  display:grid;
  gap:8px;
}
.step{
  background: rgba(17,24,39,.55);
  border:1px solid rgba(36,48,66,.7);
  border-radius: 14px;
  padding:10px;
  color:#d1d5db;
}
.step.muted{ color:var(--muted); }

.pill{
  display:inline-block;
  padding:8px 10px;
  border-radius: 999px;
  border:1px solid rgba(36,48,66,.7);
  background: rgba(11,15,23,.35);
  margin:6px 6px 0 0;
  font-weight:750;
}
.example-math{ margin-top:10px; }
.note{ margin:12px 0 0; color:var(--muted); }

.callout{
  margin-top:16px;
  padding:12px 14px;
  border-radius: 16px;
  border:1px solid rgba(36,48,66,.6);
  background: rgba(11,15,23,.28);
  color:#d1d5db;
}

.output{
  margin-top:12px;
  padding:12px 12px;
  border-radius: 16px;
  border:1px solid rgba(36,48,66,.6);
  background: rgba(11,15,23,.28);
}

.list{
  margin:0;
  padding-left:18px;
  color:#d1d5db;
}
.mini-example{ margin-top:10px; }

.faq{
  display:grid;
  gap:12px;
}
.faq-item{
  border-radius: var(--radius);
  border:1px solid rgba(36,48,66,.7);
  background: rgba(11,15,23,.28);
  padding:12px 14px;
}
.faq-item summary{
  cursor:pointer;
  font-weight:850;
}
.faq-item p{
  margin:10px 0 0;
  color:#d1d5db;
}

.footer{
  padding:26px 0 40px;
  border-top:1px solid rgba(36,48,66,.6);
}
.footer-grid{
  display:flex;
  justify-content:space-between;
  align-items:flex-start;
  gap:16px;
  flex-wrap:wrap;
}
.footer-brand{
  font-weight:900;
  margin-bottom:4px;
}
.footer-links{
  display:flex;
  gap:12px;
  flex-wrap:wrap;
  color:var(--muted);
  font-weight:650;
}
.footer-links a:hover{ color:var(--text); }

.small{ font-size:13px; }
.muted{ color:var(--muted); }

@media (max-width: 940px){
  .hero-grid{ grid-template-columns: 1fr; }
  .grid-2{ grid-template-columns: 1fr; }
  .grid-3{ grid-template-columns: 1fr; }
  .nav{ display:none; }
}