:root{
  --bg:#f4f7fb;
  --card:#ffffff;
  --ink:#162238;
  --muted:#5b6b84;
  --line:#dbe4ef;
  --brand:#0d7f74;
  --brand-dark:#08695f;
  --brand-soft:#e9faf7;
  --hero:#e9fbf5;
  --navy:#0d1930;
  --warning:#fff8e6;
  --warning-line:#e8b949;
  --shadow:0 12px 30px rgba(15,35,62,.06);
  --radius:16px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  background:var(--bg);
  color:var(--ink);
  line-height:1.6;
}
a{color:var(--brand);text-decoration:none}
a:hover{text-decoration:underline}
img{max-width:100%}
.container{width:min(100% - 40px, 980px);margin-inline:auto}
.site-header{
  background:#fff;
  border-bottom:1px solid var(--line);
  position:sticky;
  top:0;
  z-index:50;
}
.nav{
  min-height:78px;
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:24px;
}
.brand{
  font-weight:800;
  font-size:1.35rem;
  color:var(--brand);
  letter-spacing:-.02em;
}
.nav-links{display:flex;gap:26px;align-items:center;flex-wrap:wrap}
.nav-links a{color:var(--ink);font-weight:500}
.hero{
  background:var(--hero);
  padding:78px 20px;
  text-align:center;
  border-bottom:1px solid #dff2ed;
}
.hero h1{
  max-width:900px;
  margin:0 auto 16px;
  font-size:clamp(2.2rem,5vw,3.5rem);
  line-height:1.08;
  letter-spacing:-.035em;
}
.hero p{max-width:700px;margin:0 auto 28px;color:var(--muted);font-size:1.16rem}
.button{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  background:var(--brand);
  color:#fff;
  border:0;
  border-radius:9px;
  padding:13px 22px;
  font-weight:750;
  cursor:pointer;
  font-size:1rem;
}
.button:hover{background:var(--brand-dark);text-decoration:none}
.button.secondary{background:#fff;color:var(--brand);border:1px solid var(--brand)}
.section{padding:64px 0}
.section.white{background:#fff}
.section h2{font-size:2rem;line-height:1.15;margin:0 0 10px;letter-spacing:-.025em}
.section-intro{color:var(--muted);margin:0 0 26px}
.grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}
.card{
  background:var(--card);
  border:1px solid var(--line);
  border-radius:var(--radius);
  padding:26px;
  box-shadow:var(--shadow);
}
.calc-card{min-height:215px;display:flex;flex-direction:column}
.calc-card .icon{font-size:2rem;margin-bottom:18px}
.calc-card h3{font-size:1.15rem;margin:0 0 7px}
.calc-card p{color:var(--muted);margin:0 0 18px}
.calc-card .link{margin-top:auto;font-weight:750}
.badge{
  display:inline-block;
  padding:4px 9px;
  border-radius:999px;
  font-size:.78rem;
  font-weight:700;
  background:var(--brand-soft);
  color:var(--brand-dark);
}
.page{padding:48px 0 76px}
.breadcrumb{font-size:.9rem;color:var(--muted);margin-bottom:8px}
.page-title{
  margin:0;
  font-size:clamp(2rem,4vw,3rem);
  line-height:1.08;
  letter-spacing:-.035em;
}
.lead{font-size:1.08rem;color:var(--muted);margin:14px 0 24px}
.update-box{
  background:#fff;
  border:1px solid var(--line);
  border-left:4px solid var(--brand);
  border-radius:12px;
  padding:17px 18px;
  margin:20px 0 26px;
}
.update-box p{margin:3px 0;color:var(--muted)}
.calc-shell{margin:26px 0}
.calc-shell h2,.content-card h2{font-size:1.5rem;margin:0 0 20px}
.form-grid{display:grid;gap:18px}
label{display:block;font-weight:700;margin-bottom:7px}
.input-wrap{display:flex}
input,select{
  width:100%;
  border:1px solid #cbd8e7;
  background:#fff;
  padding:12px 13px;
  border-radius:8px;
  font:inherit;
  color:var(--ink);
}
.input-wrap input{border-radius:8px 0 0 8px}
.unit{
  display:flex;
  align-items:center;
  padding:0 15px;
  background:#f3f6fa;
  border:1px solid #cbd8e7;
  border-left:0;
  border-radius:0 8px 8px 0;
  white-space:nowrap;
}
.help{font-size:.87rem;color:var(--muted);margin-top:5px}
.calc-button{width:100%;margin-top:4px}
.results{display:none;margin-top:26px}
.results.is-visible{display:block}
.result-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px}
.result{
  background:var(--brand-soft);
  border-radius:12px;
  padding:18px 14px;
  text-align:center;
}
.result span{display:block;color:var(--muted);font-size:.9rem}
.result strong{display:block;color:var(--brand-dark);font-size:1.45rem;margin-top:3px}
.summary{
  background:#f7f9fc;
  border-radius:12px;
  padding:18px;
  margin-top:20px;
}
.summary h3{margin:0 0 8px}
.summary p{margin:2px 0}
.table-wrap{overflow-x:auto;margin-top:22px}
table{width:100%;border-collapse:collapse}
th,td{padding:12px 10px;border-bottom:1px solid var(--line);text-align:left}
th{background:#f7f9fc;font-size:.9rem}
.content-card{margin-top:24px}
.content-card p{margin:0 0 14px}
.formula{
  background:#f2f6fa;
  border-left:4px solid var(--brand);
  padding:15px 16px;
  margin:18px 0;
  font-weight:700;
}
.faq-item{padding:18px 0;border-bottom:1px solid var(--line)}
.faq-item:last-child{border-bottom:0}
.faq-item h3{font-size:1.05rem;margin:0 0 4px}
.faq-item p{margin:0;color:#29364b}
.related-links{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}
.related-links a{
  border:1px solid var(--line);
  border-radius:10px;
  padding:12px 14px;
  background:#fff;
  font-weight:650;
}
.note{
  background:var(--warning);
  border:1px solid #f0d887;
  border-left:4px solid var(--warning-line);
  padding:15px 17px;
  border-radius:10px;
  margin:18px 0;
}
.site-footer{
  background:var(--navy);
  color:#dbe5f5;
  padding:30px 0;
  text-align:center;
}
.site-footer p{margin:5px 0}
.footer-links{display:flex;gap:18px;justify-content:center;flex-wrap:wrap;margin:10px 0}
.site-footer a{color:#fff}
.small{font-size:.88rem;color:var(--muted)}
.two-col{display:grid;grid-template-columns:1.3fr .7fr;gap:22px}
.article h2{margin-top:34px}
.article h3{margin-top:26px}
.article ul{padding-left:22px}
.article li{margin:7px 0}
@media(max-width:760px){
  .nav{align-items:flex-start;padding:18px 0;flex-direction:column}
  .nav-links{gap:15px}
  .hero{padding:55px 20px}
  .grid,.two-col,.related-links{grid-template-columns:1fr}
  .result-grid{grid-template-columns:repeat(2,minmax(0,1fr))}
  .page{padding-top:34px}
}
@media(max-width:440px){
  .container{width:min(100% - 24px,980px)}
  .result-grid{grid-template-columns:1fr}
  .card{padding:20px}
}

/* =========================================================
   EXTRA VISUAL POLISH
   ADD THIS AT THE VERY END OF style.css
========================================================= */


/* ---------------------------------------------------------
   SOFTER WEBSITE BACKGROUND
--------------------------------------------------------- */

body {
  background:
    radial-gradient(
      circle at 10% 10%,
      rgba(13, 127, 116, 0.045),
      transparent 28%
    ),
    radial-gradient(
      circle at 90% 30%,
      rgba(34, 197, 94, 0.04),
      transparent 28%
    ),
    var(--bg);
}


/* ---------------------------------------------------------
   BETTER HEADER / GLASS EFFECT
--------------------------------------------------------- */

.site-header {
  background: rgba(255, 255, 255, 0.94);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  box-shadow: 0 3px 18px rgba(15, 35, 62, 0.035);
}


/* ---------------------------------------------------------
   LOGO POLISH
--------------------------------------------------------- */

.brand {
  position: relative;
  transition:
    transform .2s ease,
    color .2s ease;
}

.brand:hover {
  transform: translateY(-1px);
  text-decoration: none;
  color: var(--brand-dark);
}


/* ---------------------------------------------------------
   NAVIGATION HOVER LINE
--------------------------------------------------------- */

.nav-links a {
  position: relative;
  padding-bottom: 5px;
}

.nav-links a::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 0;

  width: 0;
  height: 2px;

  background: linear-gradient(
    90deg,
    var(--brand),
    #22c55e
  );

  border-radius: 10px;

  transform: translateX(-50%);

  transition: width .25s ease;
}

.nav-links a:hover {
  text-decoration: none;
}

.nav-links a:hover::after {
  width: 100%;
}


/* ---------------------------------------------------------
   MORE ATTRACTIVE HERO
--------------------------------------------------------- */

.hero {
  position: relative;
  overflow: hidden;

  background:
    radial-gradient(
      circle at 20% 30%,
      rgba(13, 127, 116, 0.13),
      transparent 30%
    ),
    radial-gradient(
      circle at 80% 65%,
      rgba(34, 197, 94, 0.10),
      transparent 28%
    ),
    linear-gradient(
      135deg,
      #e9fbf5,
      #f3fffb,
      #edf8ff
    );
}


/* decorative background circles */

.hero::before,
.hero::after {
  content: "";
  position: absolute;

  border-radius: 50%;

  pointer-events: none;
}

.hero::before {
  width: 260px;
  height: 260px;

  top: -130px;
  left: -90px;

  background:
    rgba(13, 127, 116, 0.06);
}

.hero::after {
  width: 320px;
  height: 320px;

  right: -150px;
  bottom: -190px;

  background:
    rgba(34, 197, 94, 0.055);
}


/* make hero content stay above decoration */

.hero h1,
.hero p,
.hero .button {
  position: relative;
  z-index: 2;
}


/* hero heading depth */

.hero h1 {
  color: var(--navy);

  text-shadow:
    0 2px 1px rgba(255,255,255,.8);
}


/* ---------------------------------------------------------
   BUTTON UPGRADE
--------------------------------------------------------- */

.button {
  position: relative;
  overflow: hidden;

  background:
    linear-gradient(
      135deg,
      var(--brand),
      #10a897
    );

  box-shadow:
    0 8px 20px rgba(13, 127, 116, 0.20);

  transition:
    transform .2s ease,
    box-shadow .2s ease,
    background .2s ease;
}

.button:hover {
  transform: translateY(-2px);

  box-shadow:
    0 12px 28px rgba(13, 127, 116, 0.26);

  background:
    linear-gradient(
      135deg,
      var(--brand-dark),
      var(--brand)
    );
}


/* small shine animation */

.button::before {
  content: "";

  position: absolute;

  top: 0;
  left: -120%;

  width: 80px;
  height: 100%;

  background:
    linear-gradient(
      90deg,
      transparent,
      rgba(255,255,255,.25),
      transparent
    );

  transform: skewX(-20deg);

  transition: left .55s ease;
}

.button:hover::before {
  left: 130%;
}


/* ---------------------------------------------------------
   CALCULATOR CARDS
--------------------------------------------------------- */

.calc-card {
  position: relative;

  overflow: hidden;

  transition:
    transform .25s ease,
    box-shadow .25s ease,
    border-color .25s ease;
}


.calc-card::before {
  content: "";

  position: absolute;

  left: 0;
  top: 0;

  width: 100%;
  height: 4px;

  background:
    linear-gradient(
      90deg,
      var(--brand),
      #22c55e
    );

  opacity: 0;

  transition: opacity .25s ease;
}


.calc-card:hover {
  transform: translateY(-6px);

  border-color:
    rgba(13, 127, 116, 0.24);

  box-shadow:
    0 20px 40px
    rgba(15, 35, 62, 0.10);
}


.calc-card:hover::before {
  opacity: 1;
}


/* icon animation */

.calc-card .icon {
  display: inline-block;

  transition:
    transform .25s ease;
}


.calc-card:hover .icon {
  transform:
    translateY(-3px)
    scale(1.08);
}


/* calculator link */

.calc-card .link {
  display: inline-flex;
  align-items: center;
  gap: 5px;

  transition:
    gap .2s ease,
    color .2s ease;
}


.calc-card:hover .link {
  gap: 9px;
}


/* ---------------------------------------------------------
   GENERAL CARDS
--------------------------------------------------------- */

.card {
  transition:
    transform .2s ease,
    box-shadow .2s ease,
    border-color .2s ease;
}


.content-card:hover {
  border-color:
    rgba(13, 127, 116, 0.18);

  box-shadow:
    0 16px 35px rgba(15,35,62,.075);
}


/* ---------------------------------------------------------
   UPDATE / OFGEM BOX
--------------------------------------------------------- */

.update-box {
  background:
    linear-gradient(
      135deg,
      #ffffff,
      #f0fdfa
    );

  box-shadow:
    0 8px 22px rgba(15,35,62,.045);
}


/* ---------------------------------------------------------
   INPUTS
--------------------------------------------------------- */

input,
select {
  transition:
    border-color .2s ease,
    box-shadow .2s ease,
    transform .15s ease;
}


input:hover,
select:hover {
  border-color:
    rgba(13, 127, 116, .45);
}


input:focus,
select:focus {
  outline: none;

  border-color: var(--brand);

  box-shadow:
    0 0 0 4px
    rgba(13, 127, 116, .10);
}


/* ---------------------------------------------------------
   RESULT BOXES
--------------------------------------------------------- */

.result {
  position: relative;

  overflow: hidden;

  border:
    1px solid
    rgba(13, 127, 116, .08);

  transition:
    transform .2s ease,
    box-shadow .2s ease;
}


.result:hover {
  transform: translateY(-3px);

  box-shadow:
    0 10px 22px
    rgba(13,127,116,.10);
}


.result strong {
  letter-spacing: -.4px;
}


/* small decorative shine */

.result::after {
  content: "";

  position: absolute;

  width: 70px;
  height: 70px;

  right: -30px;
  top: -30px;

  border-radius: 50%;

  background:
    rgba(13,127,116,.05);
}


/* ---------------------------------------------------------
   TABLE POLISH
--------------------------------------------------------- */

tbody tr {
  transition:
    background .2s ease;
}


tbody tr:hover {
  background:
    rgba(233,250,247,.65);
}


th {
  color: var(--navy);
}


/* ---------------------------------------------------------
   RELATED CALCULATOR LINKS
--------------------------------------------------------- */

.related-links a {
  position: relative;

  transition:
    transform .2s ease,
    background .2s ease,
    border-color .2s ease,
    box-shadow .2s ease;
}


.related-links a:hover {
  transform: translateY(-2px);

  text-decoration: none;

  background: var(--brand-soft);

  border-color:
    rgba(13,127,116,.25);

  box-shadow:
    0 8px 18px
    rgba(15,35,62,.055);
}


/* ---------------------------------------------------------
   FAQ
--------------------------------------------------------- */

.faq-item {
  transition:
    padding-left .2s ease,
    background .2s ease;
}


.faq-item:hover {
  padding-left: 8px;

  background:
    linear-gradient(
      90deg,
      rgba(233,250,247,.45),
      transparent
    );
}


/* ---------------------------------------------------------
  FORMULA
--------------------------------------------------------- */

.formula {
  border-radius: 0 10px 10px 0;

  background:
    linear-gradient(
      90deg,
      var(--brand-soft),
      #f7fafc
    );
}


/* ---------------------------------------------------------
  FOOTER
--------------------------------------------------------- */

.site-footer {
  background:
    linear-gradient(
      135deg,
      #0d1930,
      #132544
    );

  border-top:
    4px solid var(--brand);
}


/* ---------------------------------------------------------
  NICE TEXT SELECTION
--------------------------------------------------------- */

::selection {
  background:
    rgba(13, 127, 116, .20);

  color: var(--navy);
}


/* ---------------------------------------------------------
  SUBTLE PAGE LOAD ANIMATION
--------------------------------------------------------- */

@keyframes energyFadeUp {

  from {
    opacity: 0;
    transform: translateY(10px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }

}


.hero h1,
.hero p,
.calc-card,
.calc-shell {
  animation:
    energyFadeUp .45s ease both;
}


/* slightly stagger calculator cards */

.calc-card:nth-child(2) {
  animation-delay: .05s;
}

.calc-card:nth-child(3) {
  animation-delay: .10s;
}

.calc-card:nth-child(4) {
  animation-delay: .15s;
}

.calc-card:nth-child(5) {
  animation-delay: .20s;
}

.calc-card:nth-child(6) {
  animation-delay: .25s;
}


/* ---------------------------------------------------------
  ACCESSIBILITY:
  REDUCE ANIMATIONS IF USER REQUESTS IT
--------------------------------------------------------- */

@media (prefers-reduced-motion: reduce) {

  *,
  *::before,
  *::after {

    animation-duration: .01ms !important;

    animation-iteration-count: 1 !important;

    transition-duration: .01ms !important;

    scroll-behavior: auto !important;

  }

}


/* ---------------------------------------------------------
  MOBILE POLISH
--------------------------------------------------------- */

@media(max-width:760px) {

  .site-header {
    position: relative;
  }


  .calc-card:hover,
  .result:hover,
  .related-links a:hover {

    transform: none;

  }

}