/* ========== Tokens ========== */
:root{
  --bg:#05070d;
  --text:#eaf1ff;
  --muted:#9fb1da;
  --blue:#2f9bff;
  --cyan:#00e5ff;
  --red:#ff2f55;

  --card-a:rgba(255,255,255,.07);
  --card-b:rgba(255,255,255,.02);
  --item-a:rgba(255,255,255,.06);
  --item-b:rgba(255,255,255,.015);
  --field-bg:rgba(255,255,255,.05);
  --border:rgba(255,255,255,.10);
  --border-strong:rgba(255,255,255,.20);
  --shadow:rgba(0,0,0,.55);
  --focus-ring:rgba(47,155,255,.55);
  --btn-text:#031226;
  --note:rgba(234,241,255,.60);
  --font:"Cairo","Tajawal",system-ui,-apple-system,"Segoe UI",Roboto,Arial,sans-serif;
}
:root[data-theme="light"]{
  --bg:#f3f6ff;
  --text:#071225;
  --muted:#42547a;
  --card-a:rgba(255,255,255,.95);
  --card-b:rgba(255,255,255,.75);
  --item-a:rgba(255,255,255,.95);
  --item-b:rgba(240,245,255,.9);
  --field-bg:#ffffff;
  --border:rgba(7,18,37,.12);
  --border-strong:rgba(7,18,37,.25);
  --shadow:rgba(30,60,120,.18);
  --focus-ring:rgba(47,155,255,.40);
  --note:rgba(7,18,37,.60);
}

*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  min-height:100vh;
  font-family:var(--font);
  color:var(--text);
  background:
    radial-gradient(900px 520px at 75% -140px, rgba(47,155,255,.32), transparent 60%),
    radial-gradient(700px 420px at 15% 8%, rgba(255,47,85,.16), transparent 55%),
    radial-gradient(900px 520px at 50% 115%, rgba(47,155,255,.10), transparent 60%),
    var(--bg);
  background-attachment:fixed;
  -webkit-font-smoothing:antialiased;
}
:root[data-theme="light"] body{
  background:
    radial-gradient(900px 520px at 75% -140px, rgba(47,155,255,.20), transparent 60%),
    radial-gradient(700px 420px at 15% 8%, rgba(255,47,85,.09), transparent 55%),
    var(--bg);
  background-attachment:fixed;
}

/* ========== Layout ========== */
.container{
  width:min(980px,92vw);
  margin:28px auto 48px;
  display:flex;
  flex-direction:column;
  gap:16px;
}
.topbar{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:12px;
}
h1{
  margin:0;
  font-size:clamp(20px,3.4vw,28px);
  font-weight:900;
  line-height:1.3;
  background:linear-gradient(90deg,var(--text) 30%,var(--blue) 70%,var(--cyan));
  -webkit-background-clip:text;
  background-clip:text;
  color:transparent;
}
h2{
  margin:0 0 14px;
  font-size:15px;
  color:var(--muted);
  font-weight:800;
  display:flex;
  align-items:center;
  gap:10px;
}
h2::before{
  content:"";
  width:4px;
  height:16px;
  border-radius:4px;
  background:linear-gradient(180deg,var(--blue),var(--red));
}

/* ========== Tabs (segmented) ========== */
.tab-buttons{
  display:inline-flex;
  gap:4px;
  padding:5px;
  border-radius:16px;
  background:var(--item-a);
  border:1px solid var(--border);
  box-shadow:inset 0 1px 0 rgba(255,255,255,.06);
  max-width:100%;
  flex-wrap:wrap;
}
.tab-button{
  font-family:inherit;
  background:transparent;
  border:1px solid transparent;
  color:var(--muted);
  padding:9px 16px;
  border-radius:12px;
  font-weight:800;
  font-size:14px;
  cursor:pointer;
  box-shadow:none;
  transition:background .18s ease,color .18s ease;
}
.tab-button:hover{color:var(--text); transform:none; filter:none}
.tab-button.active{
  background:linear-gradient(180deg,var(--blue),#1f82e0);
  color:var(--btn-text);
  box-shadow:0 8px 20px rgba(47,155,255,.30), inset 0 1px 0 rgba(255,255,255,.25);
}

/* ========== Card ========== */
.card{
  position:relative;
  background:linear-gradient(180deg,var(--card-a),var(--card-b));
  border:1px solid var(--border);
  border-radius:20px;
  padding:22px;
  box-shadow:
    0 24px 60px var(--shadow),
    inset 0 1px 0 rgba(255,255,255,.10);
  overflow:hidden;
}
.card::before{
  content:"";
  position:absolute;
  inset:0 0 auto 0;
  height:3px;
  background:linear-gradient(90deg,var(--blue),var(--cyan),var(--red));
  opacity:.9;
  pointer-events:none;
}
.card > *{position:relative; z-index:1}

/* ========== Form ========== */
.row{display:flex; gap:12px; align-items:flex-end; flex-wrap:wrap; margin-bottom:14px}
label{flex:1; min-width:160px; color:var(--muted); font-size:13px; font-weight:700}
input,select{
  font-family:inherit;
  width:100%;
  margin-top:8px;
  padding:11px 14px;
  min-height:46px;
  font-size:16px;
  border-radius:12px;
  border:1px solid var(--border-strong);
  background:var(--field-bg);
  color:var(--text);
  outline:none;
  transition:border-color .15s ease, box-shadow .15s ease;
}
select option{color:#071225; background:#fff}
input::placeholder{color:var(--muted); opacity:.55}
input:focus,select:focus{
  border-color:var(--blue);
  box-shadow:0 0 0 4px var(--focus-ring);
}
.switch{
  display:flex; align-items:center; gap:10px;
  min-width:260px; cursor:pointer;
  color:var(--text); font-size:14px;
}
.switch input[type="checkbox"]{
  width:20px; min-width:20px; height:20px; min-height:20px;
  margin:0; padding:0; flex:0 0 auto;
  accent-color:var(--blue); box-shadow:none; background:none;
}

/* ========== Buttons ========== */
button{
  font-family:inherit;
  background:linear-gradient(180deg,var(--blue),#1f82e0);
  color:var(--btn-text);
  border:none;
  padding:12px 20px;
  min-height:46px;
  border-radius:12px;
  font-weight:800;
  font-size:15px;
  cursor:pointer;
  box-shadow:0 12px 26px rgba(47,155,255,.28), inset 0 1px 0 rgba(255,255,255,.25);
  transition:transform .15s ease, filter .15s ease, box-shadow .15s ease;
}
button:hover{transform:translateY(-2px); filter:brightness(1.06)}
button:active{transform:translateY(0)}
button:focus-visible,.tab-button:focus-visible{outline:3px solid var(--focus-ring); outline-offset:2px}
button.ghost{
  background:transparent;
  color:var(--text);
  border:1px solid var(--border-strong);
  box-shadow:none;
}
button.ghost:hover{
  border-color:var(--red);
  box-shadow:0 0 0 4px rgba(255,47,85,.14);
  filter:none;
}
button#themeToggle{white-space:nowrap}

/* ========== Results ========== */
.result-grid{
  display:grid;
  grid-template-columns:repeat(4,minmax(0,1fr));
  gap:12px;
}
.result-item{
  position:relative;
  background:linear-gradient(180deg,var(--item-a),var(--item-b));
  border:1px solid var(--border);
  border-radius:16px;
  padding:14px 16px;
  box-shadow:0 10px 24px var(--shadow), inset 0 1px 0 rgba(255,255,255,.08);
  transition:transform .18s ease, border-color .18s ease;
  overflow:hidden;
}
.result-item::before{
  content:"";
  position:absolute;
  inset:0 auto 0 0;
  width:3px;
  background:linear-gradient(180deg,var(--blue),var(--red));
  opacity:.75;
}
.result-item:hover{transform:translateY(-2px); border-color:var(--border-strong)}
.label{color:var(--muted); font-size:12.5px; font-weight:700; margin-bottom:6px; line-height:1.5}
.value{
  font-size:21px;
  font-weight:900;
  line-height:1.4;
  font-variant-numeric:tabular-nums;
  overflow-wrap:anywhere;
}

/* Tab 1 layout: 4 neat rows */
.result-item:has(#historicalEvent){grid-column:span 2}
.result-item:has(#historicalEvent) .value{font-size:16px}
.result-item:has(#ageSeconds){grid-column:1 / -1}
.result-item:has(#ageSeconds) .value{font-size:26px; color:var(--cyan)}
:root[data-theme="light"] .result-item:has(#ageSeconds) .value{color:#0a74d6}
.result-item:has(#ageYears){
  border-color:rgba(47,155,255,.55);
  background:
    linear-gradient(180deg,rgba(47,155,255,.20),rgba(47,155,255,.04)),
    linear-gradient(180deg,var(--item-a),var(--item-b));
}
.result-item:has(#ageYears) .value{font-size:34px; color:var(--blue); line-height:1.2}
.result-item:has(#petAgeHumanDetail) .value{font-size:14px; font-weight:700}

hr{
  border:none; height:1px; margin:18px 0;
  background:linear-gradient(90deg,rgba(47,155,255,.35),rgba(255,47,85,.35),transparent);
}
.converted{display:grid; grid-template-columns:1fr 1fr; gap:4px 24px}
.converted p{margin:6px 0; color:var(--muted); font-size:14px}
.converted strong{color:var(--text)}
.note{margin:12px 0 0; color:var(--note); font-size:12px}

#confettiCanvas{
  position:fixed; inset:0;
  width:100vw; height:100vh;
  pointer-events:none; z-index:9999;
}

/* ========== Responsive ========== */
@media (max-width:760px){
  .container{margin:16px auto 32px; gap:12px}
  .card{padding:18px}
  .result-grid{grid-template-columns:repeat(2,minmax(0,1fr))}
  .result-item:has(#ageYears){grid-column:span 1}
  .converted{grid-template-columns:1fr}
  .row{gap:10px; align-items:stretch}
  label{min-width:unset}
  .switch{min-width:unset}
  .result-item:hover{transform:none}
}
@media (max-width:480px){
  .topbar{flex-direction:column; align-items:stretch}
  .tab-buttons{display:flex; width:100%}
  .tab-button{flex:1 1 100%}
  .row{flex-direction:column}
  button{width:100%}
  .value{font-size:18px}
  .result-item:has(#ageYears) .value{font-size:28px}
  .result-item:has(#ageSeconds) .value{font-size:22px}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *{transition:none !important}
  button:hover,.result-item:hover{transform:none}
}