/* ---------- 1. Design tokens ---------- */
:root {
  --bg-primary: #050f0a;
  --bg-secondary: #0a1a10;
  --bg-card: #0d2018;
  --bg-card-hover: #123023;

  --green-primary: #00e676;
  --green-secondary: #00c853;
  --green-dim: #1a4d35;
  --green-glow: rgba(0, 230, 118, 0.12);

  --text-primary: #e8f5e9;
  --text-secondary: #81c784;
  --text-muted: #4caf50;

  --btn-text: #04140b;
  --header-bg: rgba(5, 15, 10, 0.88);

  --border: rgba(0, 230, 118, 0.18);
  --shadow: 0 4px 30px rgba(0, 0, 0, 0.5);
  --shadow-sm: 0 2px 12px rgba(0, 0, 0, 0.35);

  --white: #ffffff;
  --danger: #ff5252;
  --star: #ffc107;

  --radius: 20px;
  --radius-sm: 12px;
  --radius-lg: 28px;
  --radius-pill: 999px;

  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 24px;
  --space-6: 32px;
  --space-7: 48px;
  --space-8: 64px;
  --space-9: 96px;

  --container-w: 1200px;
  --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-fast: 0.15s ease;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

[data-theme="light"] {
  --bg-primary: #f5faf7;
  --bg-secondary: #eaf4ee;
  --bg-card: #ffffff;
  --bg-card-hover: #f2f9f4;

  --green-primary: #00a152;
  --green-secondary: #008f47;
  --green-dim: #d7ecdf;
  --green-glow: rgba(0, 200, 83, 0.10);

  --text-primary: #0d2018;
  --text-secondary: #1a4d35;
  --text-muted: #2e7d52;

  --btn-text: #ffffff;
  --header-bg: rgba(245, 250, 247, 0.9);

  --border: rgba(0, 180, 90, 0.2);
  --shadow: 0 4px 30px rgba(13, 32, 24, 0.08);
  --shadow-sm: 0 2px 8px rgba(13, 32, 24, 0.06);
}

/* ---------- 2. Reset and base ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 84px; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  color: var(--text-primary);
  background: var(--bg-primary);
  background-image:
    radial-gradient(900px 500px at 10% -10%, var(--green-glow), transparent 60%),
    radial-gradient(800px 500px at 100% 10%, var(--green-glow), transparent 60%);
  background-attachment: fixed;
  transition: background-color var(--transition), color var(--transition);
  overflow-x: hidden;
}
img, svg, canvas { max-width: 100%; }
a { color: var(--green-primary); text-decoration: none; transition: color var(--transition-fast); }
a:hover { color: var(--green-secondary); text-decoration: underline; }
h1, h2, h3, h4 { margin: 0 0 var(--space-3); line-height: 1.25; color: var(--text-primary); }
p { margin: 0 0 var(--space-4); }
ul, ol { margin: 0 0 var(--space-4); padding-left: 22px; }
button, input, select { font-family: inherit; font-size: 1rem; }
:focus-visible { outline: 2px solid var(--green-primary); outline-offset: 2px; }

.wrap { width: 100%; max-width: var(--container-w); margin: 0 auto; padding: 0 var(--space-5); }
.skip-link {
  position: absolute; left: -999px; top: 8px; z-index: 1000;
  background: var(--green-primary); color: var(--btn-text);
  padding: 8px 14px; border-radius: var(--radius-sm); font-weight: 700;
}
.skip-link:focus { left: 8px; }

/* ---------- 3. Header ---------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: var(--header-bg);
  -webkit-backdrop-filter: blur(14px); backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border);
}
.h-inner { display: flex; align-items: center; justify-content: space-between; gap: var(--space-4); min-height: 68px; }
.logo { display: inline-flex; align-items: center; gap: 8px; font-size: 1.25rem; font-weight: 800; color: var(--text-primary); }
.logo:hover { text-decoration: none; color: var(--text-primary); }
.logo em { font-style: normal; color: var(--green-primary); margin-left: 4px; }

.main-nav ul { display: flex; gap: var(--space-2); list-style: none; margin: 0; padding: 0; }
.main-nav a {
  display: block; padding: 8px 14px; border-radius: var(--radius-pill);
  color: var(--text-secondary); font-weight: 600; font-size: 0.95rem;
}
.main-nav a:hover, .main-nav a.active { background: var(--green-glow); color: var(--green-primary); text-decoration: none; }

.h-actions { display: flex; align-items: center; gap: var(--space-2); }
.theme-toggle {
  width: 42px; height: 42px; border-radius: 50%;
  display: grid; place-items: center; cursor: pointer;
  background: var(--bg-card); border: 1px solid var(--border);
  transition: var(--transition);
}
.theme-toggle:hover { background: var(--bg-card-hover); box-shadow: 0 0 0 4px var(--green-glow); }
.theme-toggle .ico-sun { display: none; }
[data-theme="light"] .theme-toggle .ico-moon { display: none; }
[data-theme="light"] .theme-toggle .ico-sun { display: inline; }

.nav-toggle {
  display: none; width: 42px; height: 42px; border-radius: 50%;
  background: var(--bg-card); border: 1px solid var(--border);
  cursor: pointer; padding: 0; position: relative;
}
.nav-toggle span {
  position: absolute; left: 11px; right: 11px; height: 2px;
  background: var(--green-primary); border-radius: 2px; transition: var(--transition);
}
.nav-toggle span:nth-child(1) { top: 14px; }
.nav-toggle span:nth-child(2) { top: 20px; }
.nav-toggle span:nth-child(3) { top: 26px; }
.nav-toggle[aria-expanded="true"] span:nth-child(1) { top: 20px; transform: rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { top: 20px; transform: rotate(-45deg); }

/* ---------- 4. Hero ---------- */
.hero { padding: var(--space-8) 0 var(--space-6); text-align: center; }
.hero-badge {
  display: inline-block; padding: 6px 16px; margin-bottom: var(--space-4);
  border: 1px solid var(--border); border-radius: var(--radius-pill);
  background: var(--green-glow); color: var(--green-primary);
  font-size: 0.85rem; font-weight: 700; letter-spacing: 0.3px;
}
.hero h1 { font-size: clamp(2rem, 5vw, 3.4rem); font-weight: 800; letter-spacing: -0.5px; max-width: 900px; margin: 0 auto var(--space-4); }
.hero h1 span { color: var(--green-primary); }
.hero-sub { max-width: 780px; margin: 0 auto var(--space-5); color: var(--text-secondary); font-size: 1.1rem; }
.hero-chips { display: flex; flex-wrap: wrap; justify-content: center; gap: var(--space-3); margin: 0; padding: 0; list-style: none; }
.hero-chips li {
  padding: 8px 16px; border-radius: var(--radius-pill);
  background: var(--bg-card); border: 1px solid var(--border);
  color: var(--text-secondary); font-size: 0.9rem; font-weight: 600;
}

/* ---------- 5. Tool card (left: inputs, right: result) ---------- */
.tool-section { padding: var(--space-5) 0 var(--space-7); }
.tool-card {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius-lg); box-shadow: var(--shadow); overflow: hidden;
}
.tool-grid { display: grid; grid-template-columns: 1fr; }
.tool-form { padding: var(--space-6); }
.tool-result { padding: var(--space-6); background: var(--bg-secondary); border-top: 1px solid var(--border); }
.tool-title { display: flex; align-items: center; gap: 10px; font-size: 1.2rem; margin-bottom: var(--space-5); }
.tool-title i { font-style: normal; display: grid; place-items: center; width: 36px; height: 36px; border-radius: 10px; background: var(--green-glow); }

.unit-switch {
  display: inline-flex; padding: 4px; margin-bottom: var(--space-5);
  background: var(--bg-secondary); border: 1px solid var(--border); border-radius: var(--radius-pill);
}
.unit-switch label { position: relative; cursor: pointer; }
.unit-switch input { position: absolute; opacity: 0; pointer-events: none; }
.unit-switch span {
  display: block; padding: 8px 20px; border-radius: var(--radius-pill);
  font-weight: 700; font-size: 0.92rem; color: var(--text-secondary); transition: var(--transition);
}
.unit-switch input:checked + span { background: var(--green-primary); color: var(--btn-text); }
.unit-switch input:focus-visible + span { outline: 2px solid var(--green-primary); outline-offset: 2px; }

.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: var(--space-4); }
.field { display: flex; flex-direction: column; gap: 6px; min-width: 0; }
.field.full { grid-column: 1 / -1; }
.field label { font-size: 0.88rem; font-weight: 700; color: var(--text-secondary); }
.field input, .field select {
  width: 100%; min-height: 48px; padding: 10px 14px;
  background: var(--bg-primary); color: var(--text-primary);
  border: 1px solid var(--border); border-radius: var(--radius-sm);
  transition: var(--transition-fast);
}
.field select { appearance: none; -webkit-appearance: none; padding-right: 38px; cursor: pointer;
  background-image: linear-gradient(45deg, transparent 50%, var(--green-primary) 50%), linear-gradient(135deg, var(--green-primary) 50%, transparent 50%);
  background-position: calc(100% - 20px) 21px, calc(100% - 14px) 21px;
  background-size: 6px 6px, 6px 6px; background-repeat: no-repeat;
}
.field input:focus, .field select:focus { border-color: var(--green-primary); box-shadow: 0 0 0 4px var(--green-glow); outline: none; }
.field input.invalid, .field select.invalid { border-color: var(--danger); box-shadow: 0 0 0 4px rgba(255, 82, 82, 0.12); }
.field-error { min-height: 0; font-size: 0.8rem; color: var(--danger); }
.field-hint { font-size: 0.78rem; color: var(--text-muted); }

.input-unit { position: relative; }
.input-unit input { padding-right: 56px; }
.input-unit .unit {
  position: absolute; right: 14px; top: 50%; transform: translateY(-50%);
  font-size: 0.85rem; font-weight: 700; color: var(--text-muted); pointer-events: none;
}
.is-hidden { display: none !important; }

.btn-row { display: flex; flex-wrap: wrap; gap: var(--space-3); margin-top: var(--space-5); }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  min-height: 48px; padding: 0 26px; border: 1px solid transparent; border-radius: var(--radius-pill);
  font-weight: 800; letter-spacing: 0.3px; cursor: pointer; transition: var(--transition);
}
.btn:hover { text-decoration: none; transform: translateY(-2px); }
.btn:active { transform: translateY(0); }
.btn-primary { flex: 1 1 180px; background: var(--green-primary); color: var(--btn-text); box-shadow: 0 6px 22px var(--green-glow); }
.btn-primary:hover { background: var(--green-secondary); color: var(--btn-text); }
.btn-ghost { background: transparent; color: var(--text-secondary); border-color: var(--border); }
.btn-ghost:hover { background: var(--green-glow); color: var(--green-primary); }
.btn-sm { min-height: 40px; padding: 0 18px; font-size: 0.9rem; }

/* ---------- 6. Result panel ---------- */
.result-placeholder { text-align: center; padding: var(--space-7) var(--space-4); color: var(--text-secondary); }
.result-placeholder .big { font-size: 3.2rem; display: block; margin-bottom: var(--space-3); }
.result-placeholder h3 { color: var(--text-primary); }

.result-box { animation: pop 0.45s ease both; }
@keyframes pop { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: none; } }

.r-head { display: flex; align-items: center; justify-content: space-between; gap: 10px; margin-bottom: var(--space-4); }
.r-head h3 { margin: 0; font-size: 1.15rem; color: var(--green-primary); }
.r-tag { font-size: 0.78rem; font-weight: 700; padding: 4px 12px; border-radius: var(--radius-pill); background: var(--green-glow); color: var(--green-primary); border: 1px solid var(--border); }

.r-hero {
  text-align: center; padding: var(--space-5); margin-bottom: var(--space-4);
  background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius);
  position: relative; overflow: hidden;
}
.r-hero::before { content: ""; position: absolute; inset: 0; background: radial-gradient(circle at 50% 0%, var(--green-glow), transparent 70%); pointer-events: none; }
.r-label { position: relative; font-size: 0.82rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.8px; color: var(--text-secondary); }
.r-value { position: relative; font-size: clamp(2.6rem, 6vw, 3.6rem); font-weight: 800; line-height: 1.1; color: var(--green-primary); }
.r-value small { font-size: 1.1rem; font-weight: 700; color: var(--text-secondary); margin-left: 4px; }

.r-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--space-3); margin-bottom: var(--space-4); }
.r-stat { padding: var(--space-4); background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-sm); }
.r-stat .r-label { font-size: 0.72rem; }
.r-stat .num { display: block; font-size: 1.55rem; font-weight: 800; color: var(--text-primary); line-height: 1.2; margin-top: 4px; }
.r-stat .num small { font-size: 0.8rem; font-weight: 700; color: var(--text-muted); margin-left: 3px; }

.equiv { margin-bottom: var(--space-4); }
.equiv h4 { font-size: 0.95rem; color: var(--text-secondary); margin-bottom: var(--space-3); }
.equiv-list { display: grid; grid-template-columns: repeat(auto-fit, minmax(110px, 1fr)); gap: var(--space-3); margin: 0; padding: 0; list-style: none; }
.equiv-list li { text-align: center; padding: 12px 8px; background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-sm); font-size: 0.82rem; color: var(--text-secondary); line-height: 1.4; }
.equiv-list b { display: block; font-size: 1.3rem; color: var(--text-primary); }

.chart-box { margin-bottom: var(--space-4); padding: var(--space-4); background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); }
.chart-box h4 { font-size: 0.95rem; color: var(--text-secondary); margin-bottom: var(--space-3); }
.chart-svg { display: block; width: 100%; height: auto; }
.chart-svg text { fill: var(--text-secondary); font-size: 11px; font-family: var(--font-sans); }
.chart-svg .grid-line { stroke: var(--border); stroke-width: 1; }
.chart-svg .line { fill: none; stroke: var(--green-primary); stroke-width: 3; stroke-linecap: round; stroke-linejoin: round; }
.chart-svg .area { fill: var(--green-glow); }
.chart-svg .dot { fill: var(--green-primary); stroke: var(--bg-card); stroke-width: 2; }
.chart-svg .dot-now { fill: var(--star); stroke: var(--bg-card); stroke-width: 2; }
.chart-svg .bar { fill: var(--green-primary); opacity: 0.55; }
.chart-svg .bar.on { opacity: 1; }
.chart-legend { display: flex; flex-wrap: wrap; gap: var(--space-4); margin-top: var(--space-2); font-size: 0.8rem; color: var(--text-secondary); }
.chart-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 50%; margin-right: 6px; background: var(--green-primary); }
.chart-legend i.now { background: var(--star); }

.r-note { font-size: 0.8rem; color: var(--text-muted); margin-bottom: var(--space-4); }

.share-box { padding: var(--space-4); background: var(--bg-card); border: 1px dashed var(--green-dim); border-radius: var(--radius); }
.share-box h4 { font-size: 1rem; margin-bottom: var(--space-3); }
.share-actions { display: flex; flex-wrap: wrap; gap: var(--space-2); }
.share-actions .btn { flex: 1 1 130px; }

/* Ye part sirf PDF/image export me dikhta hai */
.export-only { display: none; }
.is-exporting .export-only { display: block; }
.is-exporting .no-export { display: none !important; }
.is-exporting { width: 640px; padding: 24px; background: var(--bg-secondary); }
.is-exporting .result-box { animation: none; }
.export-credit { margin-top: var(--space-4); padding-top: var(--space-3); border-top: 1px solid var(--border); text-align: center; font-size: 0.82rem; color: var(--text-secondary); line-height: 1.7; }
.export-credit a { font-weight: 700; }

/* ---------- 7. Sections ---------- */
.section { padding: var(--space-7) 0; }
.section-alt { background: var(--bg-secondary); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.section-head { text-align: center; max-width: 760px; margin: 0 auto var(--space-6); }
.section-head h2 { font-size: clamp(1.6rem, 3.6vw, 2.3rem); }
.section-head h2 span { color: var(--green-primary); }
.section-head p { color: var(--text-secondary); }

.howto-grid { display: grid; grid-template-columns: 1fr; gap: var(--space-4); }
.howto-item {
  padding: var(--space-5); background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); transition: var(--transition);
}
.howto-item:hover { background: var(--bg-card-hover); transform: translateY(-3px); box-shadow: var(--shadow-sm); }
.howto-item .n {
  display: inline-grid; place-items: center; width: 36px; height: 36px; margin-bottom: var(--space-3);
  border-radius: 50%; background: var(--green-primary); color: var(--btn-text); font-weight: 800;
}
.howto-item h3 { font-size: 1.1rem; }
.howto-item p { margin: 0; color: var(--text-secondary); font-size: 0.95rem; }
.howto-item .tip { display: block; margin-top: var(--space-3); padding: 10px 12px; border-radius: var(--radius-sm); background: var(--green-glow); color: var(--text-primary); font-size: 0.86rem; }

/* ---------- 8. Article ---------- */
.article { max-width: 880px; margin: 0 auto; }
.article h2 { font-size: clamp(1.5rem, 3.2vw, 2rem); margin-top: var(--space-7); padding-bottom: var(--space-2); border-bottom: 2px solid var(--green-dim); }
.article h2:first-child { margin-top: 0; }
.article h3 { font-size: 1.25rem; margin-top: var(--space-6); color: var(--green-primary); }
.article p, .article li { color: var(--text-primary); opacity: 0.92; }
.article li { margin-bottom: 6px; }
.article strong { color: var(--green-primary); }

.formula {
  margin: var(--space-4) 0; padding: var(--space-4) var(--space-5);
  background: var(--bg-card); border: 1px solid var(--border); border-left: 4px solid var(--green-primary);
  border-radius: var(--radius-sm); font-weight: 700; font-size: 1.05rem; overflow-x: auto;
}
.callout {
  margin: var(--space-5) 0; padding: var(--space-4) var(--space-5);
  background: var(--green-glow); border: 1px solid var(--border); border-radius: var(--radius-sm);
}
.callout p:last-child { margin-bottom: 0; }

.table-wrap { margin: var(--space-4) 0 var(--space-5); overflow-x: auto; border: 1px solid var(--border); border-radius: var(--radius-sm); -webkit-overflow-scrolling: touch; }
.table-wrap table { width: 100%; min-width: 560px; border-collapse: collapse; background: var(--bg-card); font-size: 0.92rem; }
.table-wrap caption { padding: 12px; font-weight: 800; color: var(--green-primary); text-align: center; caption-side: top; }
.table-wrap th, .table-wrap td { padding: 10px 12px; text-align: center; border-bottom: 1px solid var(--border); }
.table-wrap th { background: var(--bg-secondary); color: var(--text-secondary); font-weight: 800; position: sticky; top: 0; }
.table-wrap tbody th { text-align: left; background: var(--bg-secondary); }
.table-wrap tbody tr:hover td { background: var(--bg-card-hover); }
.table-wrap tr:last-child th, .table-wrap tr:last-child td { border-bottom: 0; }

/* ---------- 9. FAQ ---------- */
.faq-list { max-width: 880px; margin: 0 auto; display: grid; gap: var(--space-3); }
.faq-item { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-sm); overflow: hidden; transition: var(--transition); }
.faq-item.open { border-color: var(--green-primary); box-shadow: 0 0 0 4px var(--green-glow); }
.faq-q {
  width: 100%; display: flex; align-items: center; justify-content: space-between; gap: var(--space-4);
  padding: 18px 20px; background: transparent; color: var(--text-primary);
  border: 0; text-align: left; font-weight: 700; font-size: 1.02rem; line-height: 1.4; cursor: pointer;
}
.faq-q:hover { color: var(--green-primary); }
.faq-q::after {
  content: "+"; flex: 0 0 32px; width: 32px; height: 32px; display: grid; place-items: center;
  border-radius: 50%; background: var(--green-glow); color: var(--green-primary);
  font-size: 1.4rem; font-weight: 700; line-height: 1; transition: var(--transition);
}
.faq-item.open .faq-q::after { content: "\2212"; background: var(--green-primary); color: var(--btn-text); }
.faq-a { max-height: 0; overflow: hidden; transition: max-height 0.35s ease; }
.faq-a-inner { padding: 0 20px 20px; color: var(--text-secondary); }
.faq-a-inner p:last-child { margin-bottom: 0; }

/* ---------- 10. Toast ---------- */
.toast {
  position: fixed; left: 50%; bottom: 24px; z-index: 300;
  transform: translate(-50%, 30px); opacity: 0; pointer-events: none;
  max-width: 90vw; padding: 12px 22px; border-radius: var(--radius-pill);
  background: var(--green-primary); color: var(--btn-text); font-weight: 700; box-shadow: var(--shadow);
  transition: var(--transition);
}
.toast.show { transform: translate(-50%, 0); opacity: 1; }

/* ---------- 11. Footer ---------- */
.site-footer { margin-top: var(--space-7); padding: var(--space-7) 0 var(--space-5); background: var(--bg-secondary); border-top: 1px solid var(--border); }
.f-grid { display: grid; grid-template-columns: 1fr; gap: var(--space-6); }
.site-footer p { color: var(--text-secondary); font-size: 0.93rem; }
.f-col h4 { font-size: 1rem; color: var(--green-primary); margin-bottom: var(--space-3); }
.f-col ul { list-style: none; margin: 0; padding: 0; }
.f-col li { margin-bottom: 8px; }
.f-col a { color: var(--text-secondary); font-size: 0.93rem; }
.f-col a:hover { color: var(--green-primary); }
#tools-list { max-height: 320px; overflow-y: auto; }
.f-bottom {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: var(--space-3);
  margin-top: var(--space-6); padding-top: var(--space-4); border-top: 1px solid var(--border);
}
.f-bottom p { margin: 0; }
.f-links { display: flex; flex-wrap: wrap; gap: var(--space-4); }
.f-links a { color: var(--text-secondary); font-size: 0.9rem; }
.f-links a:hover { color: var(--green-primary); }
.f-note { margin: var(--space-4) 0 0; padding: var(--space-3) var(--space-4); border-radius: var(--radius-sm); background: var(--green-glow); font-size: 0.82rem !important; }

/* ---------- 12. Responsive ---------- */
@media (min-width: 700px) {
  .howto-grid { grid-template-columns: repeat(2, 1fr); }
  .f-grid { grid-template-columns: 1.4fr 1fr 1fr 1fr; }
}
@media (min-width: 992px) {
  .tool-grid { grid-template-columns: minmax(0, 1fr) minmax(0, 1.05fr); }
  .tool-result { border-top: 0; border-left: 1px solid var(--border); }
  .tool-result .result-sticky { position: sticky; top: 90px; }
  .howto-grid { grid-template-columns: repeat(3, 1fr); }
}
@media (max-width: 860px) {
  .nav-toggle { display: block; }
  .main-nav {
    position: absolute; top: 100%; left: 0; right: 0; display: none;
    background: var(--bg-secondary); border-bottom: 1px solid var(--border); padding: var(--space-3) var(--space-5) var(--space-4);
  }
  .main-nav.open { display: block; }
  .main-nav ul { flex-direction: column; }
  .main-nav a { border-radius: var(--radius-sm); }
}
@media (max-width: 560px) {
  .wrap { padding: 0 var(--space-4); }
  .hero { padding: var(--space-7) 0 var(--space-5); }
  .tool-form, .tool-result { padding: var(--space-5) var(--space-4); }
  .form-grid { grid-template-columns: 1fr; }
  .r-grid { grid-template-columns: 1fr 1fr; }
  .section { padding: var(--space-6) 0; }
  .btn-primary { flex-basis: 100%; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; scroll-behavior: auto !important; }
}

/* Quick duration buttons */
.presets { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 4px; }
.preset {
  padding: 6px 14px; border-radius: var(--radius-pill);
  border: 1px solid var(--border); background: var(--bg-primary);
  color: var(--text-secondary); font-weight: 700; font-size: 0.82rem;
  cursor: pointer; transition: var(--transition-fast);
}
.preset:hover { background: var(--green-glow); color: var(--green-primary); border-color: var(--green-primary); }

/* ---------- Multi-tool additions ---------- */
[hidden] { display: none !important; }

.tool-tabs {
  display: flex; gap: var(--space-2); margin-bottom: var(--space-4);
  overflow-x: auto; padding-bottom: 6px; -webkit-overflow-scrolling: touch; scrollbar-width: thin;
}
.tool-tab {
  flex: 0 0 auto; display: inline-flex; align-items: center; gap: 6px;
  min-height: 44px; padding: 0 18px; border-radius: var(--radius-pill);
  background: var(--bg-card); color: var(--text-secondary);
  border: 1px solid var(--border); font-weight: 700; font-size: 0.92rem;
  cursor: pointer; white-space: nowrap; transition: var(--transition);
}
.tool-tab:hover { background: var(--bg-card-hover); color: var(--green-primary); }
.tool-tab.active { background: var(--green-primary); color: var(--btn-text); border-color: var(--green-primary); box-shadow: 0 6px 22px var(--green-glow); }

.unit-bar { margin-bottom: var(--space-4); }
.unit-bar .unit-switch { margin-bottom: 0; }
.pane-intro { margin: calc(var(--space-3) * -1) 0 var(--space-5); color: var(--text-secondary); font-size: 0.93rem; }
.height-us { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }

.howto-more-head { margin-top: var(--space-8); }
.howto-tools { display: grid; grid-template-columns: 1fr; gap: var(--space-4); }
.howto-tool {
  padding: var(--space-5); background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); transition: var(--transition);
}
.howto-tool:hover { background: var(--bg-card-hover); box-shadow: var(--shadow-sm); }
.howto-tool h3 { font-size: 1.1rem; color: var(--green-primary); }
.howto-tool ol { margin: 0 0 var(--space-3); color: var(--text-secondary); font-size: 0.95rem; }
.howto-tool li { margin-bottom: 6px; }
.howto-tool .tip { display: block; padding: 10px 12px; border-radius: var(--radius-sm); background: var(--green-glow); color: var(--text-primary); font-size: 0.86rem; }

@media (min-width: 700px) { .howto-tools { grid-template-columns: repeat(2, 1fr); } }
@media (min-width: 992px) { .howto-tools { grid-template-columns: repeat(3, 1fr); } }