:root{
  --primary:#2b6fb3;
  --accent:#d66a6a;
  --muted:#6b7280;
  --bg:#f7fafc;
}
*{box-sizing:border-box}
html,body{height:100%;margin:0;font-family:Vazir, system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial; background:var(--bg); color:#222}
a{color:inherit;text-decoration:none}

/* Header */
header{background:#fff;position:fixed;top:0;left:0;right:0;z-index:50;border-bottom:1px solid #e6eef6}
.container{max-width:1100px;margin:0 auto;padding:0 16px}
.topbar{display:flex;align-items:center;justify-content:space-between;height:64px}
.logo{display:flex;align-items:center;gap:12px}

/* منوی دسکتاپ */
.desktop-nav{display:flex;gap:14px;align-items:center;list-style:none;margin:0;padding:0}
.desktop-nav a{padding:8px 12px;border-radius:8px;font-weight:600;transition:background .25s}
.desktop-nav a:hover{background:#eef6ff}

/* دکمه همبرگری */
.menu-toggle{display:none;background:none;border:none;cursor:pointer;padding:8px;z-index:1001;position:relative}
.hamburger,.hamburger::before,.hamburger::after{display:block;width:26px;height:3px;background:#222;border-radius:3px;transition:all .3s ease-in-out}
.hamburger::before,.hamburger::after{content:""}
.hamburger::before{transform:translateY(-8px)}
.hamburger::after{transform:translateY(5px)}
.menu-toggle[aria-expanded="true"] .hamburger{background:transparent}
.menu-toggle[aria-expanded="true"] .hamburger::before{transform:translateY(0) rotate(45deg)}
.menu-toggle[aria-expanded="true"] .hamburger::after{transform:translateY(-3px) rotate(-45deg)}

/* منوی موبایل تمام‌صفحه */
.mobile-menu-overlay{
  position:fixed;top:0;right:0;bottom:0;left:0;
  background:rgba(0,0,0,0.65);backdrop-filter:blur(8px);
  display:flex;align-items:center;justify-content:center;
  opacity:0;visibility:hidden;transition:all .4s ease;z-index:1000;
}
.mobile-menu-overlay.active{opacity:1;visibility:visible}
.mobile-nav{
  list-style:none;padding:0;margin:0;text-align:center;
  transform:translateY(-40px);transition:transform .45s ease;
}
.mobile-menu-overlay.active .mobile-nav{transform:translateY(0)}
.mobile-nav a{
  color:white;font-size:1.5rem;font-weight:600;padding:16px 24px;display:block;
  border-radius:12px;transition:background .3s;
}
.mobile-nav a:hover{background:rgba(255,255,255,0.18)}

/* Hero & Carousel */
.hero{height:100vh;min-height:520px;display:grid;grid-template-rows:1fr auto}
.carousel{position:relative;height:100%;overflow:hidden}
.slide{position:absolute;inset:0;opacity:0;transition:opacity 1.2s ease-in-out;background-size:cover;background-position:center}
.slide.visible{opacity:1}
.hero-overlay{position:absolute;inset:0;background:linear-gradient(180deg,rgba(11,29,57,0.35),rgba(11,29,57,0.45));mix-blend-mode:multiply}
.hero-content{position:relative;z-index:3;color:white;padding:24px;text-align:center}
.hero h1{font-size:clamp(20px,4vw,44px);margin:0 0 12px}
.carousel-controls{position:absolute;left:16px;top:50%;transform:translateY(-50%);z-index:4;display:flex;flex-direction:column;gap:8px}
.carousel-controls button{background:rgba(255,255,255,0.15);border:1px solid rgba(255,255,255,0.18);color:white;padding:8px;border-radius:8px;backdrop-filter:blur(4px)}

/* Sections */
main{padding-top:80px}
section{padding:36px 0}
.grid{display:grid;gap:18px}
.two-col{grid-template-columns:1fr;align-items:center}
.card{background:#fff;padding:18px;border-radius:12px;box-shadow:0 6px 18px rgba(20,40,80,0.06)}
.about-img{width:100%;height:320px;object-fit:cover;border-radius:10px}

/* Products */
.products-grid{grid-template-columns:repeat(1,1fr)}
.product-card img{width:100%;height:180px;object-fit:cover;border-radius:8px}

/* Kaliteh */
.kaliteh-grid{display:grid;grid-template-columns:repeat(8,100px);gap:6px;justify-content:center}
.swatch{width:100px;height:100px;border-radius:6px;overflow:hidden;border:1px solid #e2e8f0}
.swatch img{width:100%;height:100%;object-fit:cover}

/* Contact */
form{display:grid;gap:12px}
input,textarea,button{font-family:inherit}
input,textarea{padding:10px;border:1px solid #d1d5db;border-radius:8px}
button{background:var(--primary);color:white;padding:10px 14px;border:none;border-radius:8px;font-weight:700;cursor:pointer}

/* Footer */
footer{background:#0f1724;color:#e6eef6;padding:24px 0;margin-top:32px}
.footer-grid{display:flex;flex-wrap:wrap;gap:18px;align-items:center;justify-content:space-between}

/* Responsive */
@media (min-width:720px){
  .two-col{grid-template-columns:1fr 1fr}
  .products-grid{grid-template-columns:repeat(3,1fr)}
}
@media (max-width:719px){
  .menu-toggle{display:block}
  .desktop-nav{display:none}
  .kaliteh-grid{grid-template-columns:repeat(4,1fr)}
}
@media (max-width:420px){
  .kaliteh-grid{grid-template-columns:repeat(3,1fr)}
  .hero{min-height:480px}
  .topbar{height:56px}

  /* دکمه برگشت به بالا - زیبا و نرم */
.back-to-top {
  position: fixed;
  right: 20px;
  bottom: 24px;
  width: 48px;
  height: 48px;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: 50%;
  font-size: 24px;
  line-height: 48px;
  text-align: center;
  cursor: pointer;
  box-shadow: 0 8px 20px rgba(43, 111, 179, 0.35);
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  z-index: 90;
  backdrop-filter: blur(10px);
  border: 3px solid rgba(255,255,255,0.2);
}
/* دکمه برگشت به بالا - کاملاً درست و تست شده */
.back-to-top {
  position: fixed;
  right: 20px;
  bottom: 24px;
  width: 52px;
  height: 52px;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: 50%;
  font-size: 28px;
  font-weight: 900;
  cursor: pointer;
  box-shadow: 0 8px 24px rgba(43, 111, 179, 0.4);
  z-index: 90;
  display: flex;
  align-items: center;
  justify-content: center;
  
  /* مهم: در حالت عادی مخفی باشه */
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}
/* دکمه برگشت به بالا — نسخه نهایی بدون باگ */
.back-to-top {
  position: fixed;
  right: 20px;
  bottom: 28px;
  width: 52px;
  height: 52px;
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 50%;
  font-size: 32px;
  font-weight: 900;
  cursor: pointer;
  box-shadow: 0 8px 25px rgba(43,111,179,0.45);
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transform: translateY(30px);
  transition: all 0.45s ease;
  pointer-events: none;
}

.back-to-top.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
  pointer-events: auto;
}

.back-to-top:hover {
  background: #1e5a94;
  transform: translateY(-8px) scale(1.12);
}

.back-to-top span {
  animation: float 2s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}

.footer-links {
  display: flex;
  gap: 18px;
  align-items: center;
  flex-wrap: wrap;
  font-size: 13.5px;
}

.footer-links a {
  display: flex;
  align-items: center;
  gap: 6px;
  color: #e6eef6;
  text-decoration: none;
  transition: color .3s;
}

.footer-links a:hover {
  color: #facc15;
}

.footer-links svg {
  width: 14px !important;
  height: 14px !important;
  flex-shrink: 0;
}
}