:root{
  --bg: #071026;
  --card: #081428;
  --panel: #0f2b3a;
  --muted: #98a4b3;
  --text: #e6eef6;
  --accent: #4aa3e0;
  --accent-2: #7ad3b7;
  --mono: #06101a;
  --glass: rgba(255,255,255,0.03);
  --success: #7ad3b7;
  --danger: #e06b6b;

  --radius: 12px;
  --pad: 14px;
  --gap: 12px;
  --max-width: 1200px;

  --btn-h: 36px;
  --font-sans: "Inter", "Segoe UI", Roboto, system-ui, -apple-system, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, "Roboto Mono", monospace;
}

/* Reset & base */
*{box-sizing:border-box}
html,body{height:100%;margin:0}
body{
  font-family:var(--font-sans);
  background: radial-gradient(900px 300px at 6% 8%, rgba(74,163,224,0.03), transparent 8%),
              linear-gradient(180deg, #031023 0%, var(--bg) 60%);
  color:var(--text);
  padding:18px;
  -webkit-font-smoothing:antialiased;
  -moz-osx-font-smoothing:grayscale;
  display:flex;
  justify-content:center;
}

/* App container */
.app{
  width:100%;
  max-width:var(--max-width);
  display:flex;
  flex-direction:column;
  gap:18px;
}

/* TOPBAR */
.topbar{
  display:flex;
  align-items:center;
  gap:16px;
  padding:10px 14px;
  border-radius:var(--radius);
  background: linear-gradient(180deg, rgba(255,255,255,0.01), rgba(255,255,255,0.02));
  border:1px solid var(--panel);
  box-shadow: 0 8px 26px rgba(0,0,0,0.45);
}

/* left / center / right layout */
.topbar .left { flex:0 0 auto; display:flex; align-items:center; gap:8px; }
.topbar .center { flex:1 1 auto; text-align:center; }
.topbar .right { flex:0 0 auto; display:flex; gap:8px; align-items:center; }

/* Home button (left, distinct color) */
.home-btn{
  display:inline-flex;
  align-items:center;
  gap:8px;
  padding:8px 12px;
  background: linear-gradient(180deg, #6fc0ff, #4aa3e0);
  color: #022831;
  border-radius:10px;
  font-weight:700;
  text-decoration:none;
  box-shadow: 0 6px 14px rgba(30,120,160,0.12);
  height: var(--btn-h);
  line-height:1;
  border:0;
}
.home-btn:hover{ transform:translateY(-3px); box-shadow:0 10px 20px rgba(30,120,160,0.14) }

/* Title */
.title{ margin:0; font-size:1.05rem; letter-spacing:0.2px; color:var(--accent) }
.subtitle{ font-size:0.9rem; color:var(--muted); margin-top:4px }

/* action buttons in topbar */
.btn { height: var(--btn-h); padding:6px 12px; border-radius:8px; border:0; cursor:pointer; font-weight:700; background:var(--accent); color:white; display:inline-flex; gap:8px; align-items:center; }
.btn.ghost { background:transparent; color:var(--accent); border:1px solid rgba(74,163,224,0.14); }
.btn.action{ min-width:86px; }

/* container grid */
.container{
  display:grid;
  grid-template-columns: 1fr 380px;
  gap:18px;
  align-items:start;
}

/* card */
.card{
  background: linear-gradient(180deg, rgba(255,255,255,0.01), var(--card));
  border:1px solid var(--panel);
  border-radius:var(--radius);
  padding:var(--pad);
  box-shadow: 0 8px 26px rgba(0,0,0,0.35);
}

/* card titles */
.card-title{ font-weight:700; color:var(--accent); margin-bottom:10px; font-size:0.98rem }

/* form layout */
.form-card .row{ display:flex; gap:12px; margin-bottom:12px; }
.field{ flex:1 1 auto; display:flex; flex-direction:column; gap:6px; min-width:0; }
.field.full{ grid-column:1/-1; width:100% }
.field label{ color:var(--muted); font-size:0.92rem; font-weight:600; }
.field input[type="number"], .field input[type="text"], .field select{
  padding:8px 10px; border-radius:8px; border:1px solid var(--panel); background:var(--mono); color:var(--text); font-size:0.95rem; outline:none;
}
.field .help{ font-size:0.82rem; color:var(--muted); margin-top:4px }

/* notice box */
.notice{ background: linear-gradient(180deg, rgba(122,211,183,0.03), rgba(74,163,224,0.01)); border-radius:8px; padding:10px; border:1px solid rgba(255,255,255,0.02); color:var(--muted); font-size:0.92rem }

/* metric blocks (results) */
.metric{ background: linear-gradient(180deg, rgba(0,0,0,0.12), rgba(0,0,0,0.06)); padding:12px; border-radius:8px; border:1px solid rgba(255,255,255,0.03); margin-bottom:12px; }
.metric-label{ color:var(--muted); font-weight:700; margin-bottom:6px; font-size:0.86rem }
.metric-value{ font-size:1.15rem; font-weight:800; color:var(--accent-2) }

/* grid for two metrics */
.grid-2{ display:grid; grid-template-columns: 1fr 1fr; gap:12px; }

/* aside help text */
.help-block{ color:var(--muted); font-size:0.9rem; line-height:1.45 }

/* small muted */
.small-muted{ color:var(--muted); font-size:0.85rem }

/* monospace */
.mono{ font-family:var(--font-mono); font-size:0.92rem; color:var(--text) }

/* hr style */
hr{ border:0; height:1px; background: linear-gradient(90deg, transparent, rgba(255,255,255,0.03), transparent); margin:12px 0 }

/* compact buttons */
.btn.compact{ padding:6px 10px; height:32px; font-size:0.92rem }
.btn.ghost.compact{ border:1px solid rgba(74,163,224,0.12); color:var(--accent) }

/* custom radios and checkboxes */
.mode-options{ display:flex; gap:10px; align-items:center; }
.radio, .checkbox{ display:inline-flex; align-items:center; gap:8px; cursor:pointer; user-select:none; color:var(--muted); font-weight:600; font-size:0.9rem; }
.radio input, .checkbox input{ appearance:none; -webkit-appearance:none; width:18px; height:18px; margin:0; border-radius:6px; border:2px solid rgba(255,255,255,0.06); background:transparent; display:inline-block; position:relative; }
.radio input:focus, .checkbox input:focus{ outline:3px solid rgba(122,211,183,0.07); outline-offset:3px; }

/* radio specific */
.radio input{ border-radius:50%; width:18px; height:18px; }
.radio input::after{ content:''; position:relative; display:block; width:10px; height:10px; border-radius:50%; transform:scale(0); transition:transform .12s ease; margin:auto; top:3px; }
.radio input:checked{ border-color:var(--accent-2); background:rgba(122,211,183,0.06); }
.radio input:checked::after{ transform:scale(1); background:var(--accent-2); }

/* checkbox specific */
.checkbox input{ border-radius:6px; width:18px; height:18px; }
.checkbox input::after{ content:'✔'; color:transparent; font-size:12px; display:block; text-align:center; line-height:14px; transform:scale(0); transition:transform .12s ease; }
.checkbox input:checked{ border-color:var(--accent-2); background:rgba(122,211,183,0.04); }
.checkbox input:checked::after{ color:var(--accent-2); transform:scale(1); }

/* accessibility helpers */
.sr-only{ position:absolute!important; width:1px!important; height:1px!important; padding:0!important; margin:-1px!important; overflow:hidden!important; clip:rect(0,0,0,0)!important; white-space:nowrap!important; border:0!important; }

/* footer */
.footer{ text-align:center; color:var(--muted); font-size:0.9rem; padding:8px 0 }

/* responsive */
@media (max-width:980px){
  .container{ grid-template-columns: 1fr; }
  .topbar{ flex-direction:column; align-items:stretch; gap:12px }
  .topbar .center{ text-align:left }
  .topbar .right{ justify-content:flex-start }
  .grid-2{ grid-template-columns: 1fr }
  .form-card .row{ flex-direction:column }
}

/* focus states */
input:focus, select:focus, button:focus { outline: 3px solid rgba(122,211,183,0.06); outline-offset:3px; }

/* small polish */
button:hover{ transform:translateY(-1px); transition:transform .12s ease }