/* Melbourne Tropical - Premium Tropical Aquarium Theme */
:root{
  --ocean:#0A6CF1; --navy:#041B38; --green:#00B67A; --white:#fff;
  --bg:#f6fafe; --surface:#ffffff; --text:#0d2236; --muted:#5b7185;
  --border:#e2ecf5; --shadow:0 10px 30px rgba(4,27,56,.08);
  --radius:16px; --max:1200px;
  --grad:linear-gradient(135deg,var(--ocean),var(--green));
  --grad-hero:linear-gradient(160deg,#041B38 0%,#073a73 55%,#0A6CF1 100%);
}
[data-theme="dark"]{
  --bg:#04101f; --surface:#0a1f38; --text:#e8f1fb; --muted:#9fb4cb;
  --border:#143055; --shadow:0 10px 30px rgba(0,0,0,.4);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:'Inter',system-ui,-apple-system,Segoe UI,Roboto,sans-serif;
  background:var(--bg);color:var(--text);line-height:1.65;font-size:16px}
img{max-width:100%;height:auto;display:block}
a{color:var(--ocean);text-decoration:none}
a:hover{text-decoration:underline}
.container{max-width:var(--max);margin:0 auto;padding:0 20px}
.section{padding:64px 0}
h1,h2,h3{line-height:1.2;color:var(--text);font-weight:800;letter-spacing:-.02em}
h1{font-size:clamp(2rem,5vw,3.2rem)} h2{font-size:clamp(1.5rem,3vw,2.2rem)}
.section-head{text-align:center;max-width:680px;margin:0 auto 40px}
.section-head p{color:var(--muted)}
.eyebrow{color:var(--green);font-weight:700;text-transform:uppercase;letter-spacing:.08em;font-size:.8rem}

/* Buttons */
.btn{display:inline-flex;align-items:center;gap:.5rem;padding:.8rem 1.5rem;border-radius:999px;
  font-weight:700;border:none;cursor:pointer;transition:.2s;text-decoration:none}
.btn-primary{background:var(--grad);color:#fff;box-shadow:0 8px 20px rgba(10,108,241,.3)}
.btn-primary:hover{transform:translateY(-2px);text-decoration:none;color:#fff}
.btn-ghost{background:rgba(255,255,255,.12);color:#fff;border:1px solid rgba(255,255,255,.4)}
.btn-ghost:hover{background:rgba(255,255,255,.22);color:#fff;text-decoration:none}
.btn-outline{background:transparent;border:2px solid var(--ocean);color:var(--ocean)}

/* Header */
.site-header{position:sticky;top:0;z-index:100;background:color-mix(in srgb,var(--surface) 88%,transparent);
  backdrop-filter:blur(12px);border-bottom:1px solid var(--border)}
.nav{display:flex;align-items:center;justify-content:space-between;height:68px;gap:1rem}
.logo{display:flex;align-items:center;gap:.5rem;font-weight:900;font-size:1.2rem;color:var(--text)}
.logo:hover{text-decoration:none}
.logo .dot{width:30px;height:30px;border-radius:9px;background:var(--grad);display:grid;place-items:center;color:#fff;font-size:1rem}
.menu{display:flex;gap:.3rem;list-style:none;margin:0;padding:0;align-items:center}
.menu a{color:var(--text);padding:.55rem .8rem;border-radius:10px;font-weight:600;font-size:.95rem}
.menu a:hover{background:var(--bg);text-decoration:none;color:var(--ocean)}
.nav-tools{display:flex;align-items:center;gap:.5rem}
.icon-btn{background:var(--bg);border:1px solid var(--border);width:40px;height:40px;border-radius:10px;
  cursor:pointer;font-size:1.1rem;color:var(--text);display:grid;place-items:center}
.hamburger{display:none}
/* Mega menu */
.has-mega{position:relative}
.mega{position:absolute;top:120%;left:50%;transform:translateX(-50%) translateY(8px);min-width:520px;
  background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);
  padding:1.2rem;display:grid;grid-template-columns:1fr 1fr;gap:.4rem;opacity:0;visibility:hidden;transition:.2s;z-index:200}
.has-mega:hover .mega{opacity:1;visibility:visible;transform:translateX(-50%) translateY(0)}
.mega a{display:block;padding:.5rem .7rem;border-radius:8px;font-size:.9rem}

/* Hero */
.hero{background:var(--grad-hero);color:#fff;position:relative;overflow:hidden;padding:90px 0 110px}
.hero h1{color:#fff;max-width:14ch}
.hero p{font-size:1.2rem;color:#cfe2ff;max-width:46ch;margin:1rem 0 2rem}
.hero .btns{display:flex;gap:1rem;flex-wrap:wrap}
.hero .wave{position:absolute;bottom:-1px;left:0;width:100%;line-height:0}
.hero .wave svg{width:100%;height:80px}
.fish-swim{position:absolute;font-size:2rem;opacity:.35;animation:swim linear infinite;pointer-events:none}
@keyframes swim{from{transform:translateX(-10vw)}to{transform:translateX(110vw)}}
@media(prefers-reduced-motion:reduce){.fish-swim{display:none}}

/* Cards & grids */
.grid{display:grid;gap:1.2rem}
.g2{grid-template-columns:repeat(2,1fr)} .g3{grid-template-columns:repeat(3,1fr)} .g4{grid-template-columns:repeat(4,1fr)}
.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:1.4rem;
  box-shadow:var(--shadow);transition:.2s;height:100%}
.card:hover{transform:translateY(-4px)}
.card h3{font-size:1.1rem;margin:.3rem 0 .5rem}
.card p{color:var(--muted);font-size:.92rem;margin:0 0 .8rem}
.card .ico{width:46px;height:46px;border-radius:12px;background:var(--grad);display:grid;place-items:center;color:#fff;font-size:1.3rem;margin-bottom:.6rem}
.tag{display:inline-block;background:var(--bg);color:var(--muted);padding:.2rem .65rem;border-radius:999px;font-size:.75rem;font-weight:700;border:1px solid var(--border)}
.badge{display:inline-block;padding:.2rem .6rem;border-radius:999px;font-size:.72rem;font-weight:800;color:#fff}
.badge.Beginner,.badge.Low{background:var(--green)} .badge.Intermediate,.badge.Moderate{background:#f0a500}
.badge.Advanced,.badge.High,.badge.Critical{background:#e0566b}
.card-img{aspect-ratio:16/10;border-radius:12px;background:var(--grad-hero);margin:-1.4rem -1.4rem 1rem;
  display:grid;place-items:center;color:rgba(255,255,255,.5);font-size:2.5rem;overflow:hidden}

/* Categories chips */
.chips{display:flex;flex-wrap:wrap;gap:.5rem;justify-content:center}
.chip{background:var(--surface);border:1px solid var(--border);padding:.5rem 1rem;border-radius:999px;font-weight:600;font-size:.9rem;color:var(--text)}
.chip:hover{background:var(--grad);color:#fff;text-decoration:none;border-color:transparent}

/* Breadcrumb */
.breadcrumb{font-size:.85rem;color:var(--muted);padding:1rem 0}
.breadcrumb a{color:var(--muted)}

/* Calculator */
.calc{display:grid;grid-template-columns:1fr 1fr;gap:1.5rem}
.calc-form{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:1.6rem;box-shadow:var(--shadow)}
.field{margin-bottom:1rem}
.field label{display:block;font-weight:700;margin-bottom:.35rem;font-size:.9rem}
.field input,.field select{width:100%;padding:.7rem .9rem;border:1px solid var(--border);border-radius:10px;
  background:var(--bg);color:var(--text);font-size:1rem}
.calc-result{background:var(--grad);color:#fff;border-radius:var(--radius);padding:1.6rem;box-shadow:var(--shadow)}
.calc-result .big{font-size:2rem;font-weight:900;margin:.3rem 0 1rem}
.calc-result table{width:100%;border-collapse:collapse}
.calc-result td{padding:.5rem 0;border-bottom:1px solid rgba(255,255,255,.2);font-size:.92rem}
.calc-result td:last-child{text-align:right;font-weight:700}

/* Article */
.prose{max-width:760px;margin:0 auto}
.prose h2{margin-top:2rem} .prose p{color:var(--text)}
.toc{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:1.2rem 1.5rem;margin-bottom:2rem}
.toc ul{margin:.5rem 0 0;padding-left:1.2rem}
.faq{border:1px solid var(--border);border-radius:12px;margin-bottom:.7rem;background:var(--surface);overflow:hidden}
.faq summary{padding:1rem 1.2rem;font-weight:700;cursor:pointer;list-style:none}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{content:'+';float:right;color:var(--green);font-weight:900}
.faq[open] summary::after{content:'–'}
.faq .a{padding:0 1.2rem 1rem;color:var(--muted)}
.author-box{display:flex;gap:1rem;align-items:center;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:1.2rem;margin:2rem 0}
.author-box .av{width:54px;height:54px;border-radius:50%;background:var(--grad);flex:none}
.share a{display:inline-grid;place-items:center;width:38px;height:38px;border-radius:50%;background:var(--bg);border:1px solid var(--border);margin-right:.4rem}

/* spec table */
.spec{width:100%;border-collapse:collapse;background:var(--surface);border-radius:var(--radius);overflow:hidden;border:1px solid var(--border)}
.spec td{padding:.7rem 1rem;border-bottom:1px solid var(--border);font-size:.92rem}
.spec td:first-child{font-weight:700;width:42%;color:var(--muted)}

/* Newsletter / CTA band */
.band{background:var(--grad-hero);color:#fff;border-radius:24px;padding:3rem;text-align:center}
.band h2{color:#fff}
.band form{display:flex;gap:.6rem;max-width:460px;margin:1.2rem auto 0}
.band input{flex:1;padding:.8rem 1rem;border-radius:999px;border:none;font-size:1rem}

/* Ad slot */
.ad-slot{background:repeating-linear-gradient(45deg,var(--bg),var(--bg) 10px,transparent 10px,transparent 20px);
  border:1px dashed var(--border);border-radius:12px;min-height:90px;display:grid;place-items:center;color:var(--muted);font-size:.8rem;margin:1.5rem 0}

/* Footer */
.footer{background:var(--navy);color:#bcd2ea;padding:56px 0 24px;margin-top:64px}
.footer h4{color:#fff;font-size:1rem;margin:0 0 1rem}
.footer a{color:#bcd2ea;display:block;padding:.25rem 0;font-size:.9rem}
.footer a:hover{color:#fff}
.footer .cols{display:grid;grid-template-columns:1.5fr 1fr 1fr 1fr;gap:2rem}
.footer .bottom{border-top:1px solid #0e2c50;margin-top:2rem;padding-top:1.5rem;text-align:center;font-size:.85rem;color:#7e9bbd}
.flash{background:var(--green);color:#fff;padding:.8rem 1rem;border-radius:10px;margin:1rem 0;font-weight:600}

/* Mobile */
@media(max-width:900px){
  .g4{grid-template-columns:repeat(2,1fr)} .g3{grid-template-columns:repeat(2,1fr)}
  .calc{grid-template-columns:1fr} .footer .cols{grid-template-columns:1fr 1fr}
  .menu{position:fixed;inset:68px 0 auto 0;flex-direction:column;background:var(--surface);
    border-bottom:1px solid var(--border);padding:1rem;display:none;align-items:stretch}
  .menu.open{display:flex} .menu a{padding:.9rem}
  .hamburger{display:grid} .has-mega .mega{position:static;transform:none;min-width:0;grid-template-columns:1fr;
    box-shadow:none;border:none;opacity:1;visibility:visible;padding:.3rem 0 .3rem 1rem}
}
@media(max-width:560px){.g4,.g3,.g2{grid-template-columns:1fr}.footer .cols{grid-template-columns:1fr}.band form{flex-direction:column}}