/* ============================================
   武汉海康济达大药房有限公司 — 企业官网
   Design: 专业 · 信赖 · 温暖
   ============================================ */

/* ---- CSS Variables ---- */
:root {
  --color-primary: #1a6b5a;
  --color-primary-light: #e8f5f0;
  --color-primary-dark: #0f4a3d;
  --color-accent: #d4933d;
  --color-accent-light: #fef7e8;
  --color-accent-dark: #b87a2e;
  --color-blue: #4a7eb5;
  --color-purple: #8b5e9e;
  --color-coral: #e07b5a;
  --color-teal: #3d9e8b;

  --color-bg: #fafcfa;
  --color-surface: #ffffff;
  --color-text: #1a1f1d;
  --color-text-secondary: #5a6d65;
  --color-text-muted: #8a9a93;
  --color-border: #e0e8e4;
  --color-border-light: #f0f4f2;

  --font-display: 'Playfair Display', 'Noto Sans SC', serif;
  --font-body: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, sans-serif;

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --radius-2xl: 2.5rem;

  --shadow-sm: 0 1px 3px rgba(26, 107, 90, 0.06);
  --shadow-md: 0 4px 20px rgba(26, 107, 90, 0.08);
  --shadow-lg: 0 8px 40px rgba(26, 107, 90, 0.10);
  --shadow-xl: 0 16px 60px rgba(26, 107, 90, 0.12);

  --max-width: 1280px;
  --nav-height: 72px;
}

/* ---- Reset & Base ---- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

a {
  text-decoration: none;
  color: inherit;
}

ul { list-style: none; }

img { max-width: 100%; display: block; }

/* ---- Container ---- */
.section-container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---- Section Headers ---- */
.section-header {
  text-align: center;
  margin-bottom: 64px;
}

.section-tag {
  display: inline-block;
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--color-primary);
  background: var(--color-primary-light);
  padding: 6px 16px;
  border-radius: 20px;
  margin-bottom: 16px;
}

.section-title {
  font-family: var(--font-display);
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-text);
  margin-bottom: 16px;
  letter-spacing: -0.02em;
}

.section-desc {
  font-size: 1.1rem;
  color: var(--color-text-secondary);
  max-width: 560px;
  margin: 0 auto;
  line-height: 1.7;
}

/* ---- Navigation ---- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-height);
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--color-border-light);
  transition: all 0.3s ease;
}

.nav.scrolled {
  box-shadow: var(--shadow-sm);
  background: rgba(255, 255, 255, 0.95);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-primary-dark);
}

.logo-icon svg {
  display: block;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 8px;
}

.nav-link {
  padding: 8px 18px;
  border-radius: var(--radius-md);
  font-size: 0.925rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: all 0.25s ease;
  position: relative;
}

.nav-link:hover,
.nav-link.active {
  color: var(--color-primary);
  background: var(--color-primary-light);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  z-index: 1001;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: all 0.3s ease;
}

/* ---- Hero Section ---- */
.hero {
  min-height: 100dvh;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden;
  padding: calc(var(--nav-height) + 40px) 0 80px;
}

.hero-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
}

.hero-pattern {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 60% at 20% 50%, rgba(26, 107, 90, 0.06) 0%, transparent 60%),
    radial-gradient(ellipse 60% 50% at 80% 20%, rgba(212, 147, 61, 0.05) 0%, transparent 60%);
}

.hero-circle {
  position: absolute;
  border-radius: 50%;
  border: 1px solid rgba(26, 107, 90, 0.08);
}

.hero-circle-1 {
  width: 600px;
  height: 600px;
  top: -200px;
  right: -150px;
}

.hero-circle-2 {
  width: 300px;
  height: 300px;
  bottom: -50px;
  left: -80px;
  border-color: rgba(212, 147, 61, 0.1);
}

.hero-circle-3 {
  width: 150px;
  height: 150px;
  top: 40%;
  right: 45%;
  border-color: rgba(74, 126, 181, 0.08);
}

.hero-content {
  position: relative;
  z-index: 1;
  flex: 1;
  max-width: 640px;
  padding: 0 24px 0 calc((100vw - var(--max-width)) / 2 + 24px);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-primary);
  background: var(--color-primary-light);
  padding: 8px 16px;
  border-radius: 20px;
  margin-bottom: 28px;
  animation: fadeInUp 0.6s ease backwards;
}

.badge-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--color-primary);
  animation: pulse 2s infinite;
}

.hero-title {
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 5.5vw, 4rem);
  font-weight: 700;
  line-height: 1.15;
  color: var(--color-text);
  margin-bottom: 24px;
  letter-spacing: -0.03em;
}

.title-line {
  display: block;
  animation: fadeInUp 0.6s 0.1s ease backwards;
}

.title-line.accent {
  color: var(--color-primary);
  animation-delay: 0.2s;
}

.hero-desc {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  line-height: 1.8;
  margin-bottom: 36px;
  max-width: 520px;
  animation: fadeInUp 0.6s 0.3s ease backwards;
}

.hero-actions {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 52px;
  flex-wrap: wrap;
  animation: fadeInUp 0.6s 0.4s ease backwards;
}

.hero-stats {
  display: flex;
  align-items: center;
  gap: 32px;
  padding: 24px 0;
  border-top: 1px solid var(--color-border-light);
  animation: fadeInUp 0.6s 0.5s ease backwards;
}

.stat-item {
  text-align: center;
}

.stat-number {
  display: block;
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1.2;
}

.stat-label {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.stat-divider {
  width: 1px;
  height: 36px;
  background: var(--color-border);
}

/* Hero Visual */
.hero-visual {
  position: relative;
  z-index: 1;
  flex: 0 0 420px;
  padding-right: calc((100vw - var(--max-width)) / 2 + 24px);
  display: none;
}

.hero-card {
  background: var(--color-surface);
  border-radius: var(--radius-2xl);
  padding: 40px;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--color-border-light);
  animation: float 6s ease-in-out infinite;
}

.hero-card.secondary {
  position: absolute;
  bottom: -30px;
  right: 20px;
  padding: 28px;
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-md);
  animation: float 6s ease-in-out 1s infinite;
  background: var(--color-accent-light);
  border-color: rgba(212, 147, 61, 0.15);
}

.card-inner {
  text-align: center;
}

.hero-card-icon {
  margin: 0 auto 16px;
}

.hero-card h3 {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 6px;
}

.hero-card p {
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

.hero-scroll {
  position: absolute;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  color: var(--color-text-muted);
  font-size: 0.8rem;
  animation: fadeInUp 0.6s 0.8s ease backwards, bounce 2s 1.5s infinite;
  z-index: 1;
}

/* ---- Buttons ---- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-body);
  font-size: 0.95rem;
  font-weight: 600;
  padding: 14px 28px;
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  position: relative;
  overflow: hidden;
}

.btn:active {
  transform: scale(0.98);
}

.btn-primary {
  background: var(--color-primary);
  color: white;
  box-shadow: 0 4px 16px rgba(26, 107, 90, 0.25);
}

.btn-primary:hover {
  background: var(--color-primary-dark);
  box-shadow: 0 6px 24px rgba(26, 107, 90, 0.35);
  transform: translateY(-2px);
}

.btn-outline {
  background: var(--color-surface);
  color: var(--color-primary);
  border: 1.5px solid var(--color-primary);
}

.btn-outline:hover {
  background: var(--color-primary-light);
  transform: translateY(-2px);
}

.btn-full {
  width: 100%;
  justify-content: center;
}

/* ---- Services Section ---- */
.services {
  padding: 100px 0;
  background: var(--color-surface);
}

.services-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 24px;
}

.service-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-xl);
  padding: 36px;
  transition: all 0.35s cubic-bezier(0.16, 1, 0.3, 1);
  position: relative;
  overflow: hidden;
}

.service-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--accent, var(--color-primary));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

.service-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-lg);
  border-color: transparent;
}

.service-card:hover::before {
  transform: scaleX(1);
}

.service-icon-box {
  width: 60px;
  height: 60px;
  border-radius: var(--radius-md);
  background: color-mix(in srgb, var(--accent, var(--color-primary)) 10%, white);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
  color: var(--accent, var(--color-primary));
  transition: all 0.3s ease;
}

.service-card:hover .service-icon-box {
  background: var(--accent, var(--color-primary));
  color: white;
  transform: scale(1.05);
}

.service-card h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 12px;
  color: var(--color-text);
}

.service-card p {
  font-size: 0.925rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 20px;
}

.service-features {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.service-features li {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  padding-left: 20px;
  position: relative;
}

.service-features li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent, var(--color-primary));
}

/* ---- About Section ---- */
.about {
  padding: 100px 0;
}

.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 72px;
  align-items: center;
}

.about-visual {
  position: relative;
}

.about-image-placeholder {
  width: 100%;
  aspect-ratio: 4/3;
  background: linear-gradient(135deg, var(--color-primary-light) 0%, var(--color-accent-light) 100%);
  border-radius: var(--radius-2xl);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  position: relative;
}

.about-image-placeholder::before {
  content: '';
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 30% 30%, rgba(255,255,255,0.4) 0%, transparent 50%),
    radial-gradient(circle at 70% 70%, rgba(26,107,90,0.1) 0%, transparent 50%);
}

.about-emblems {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  padding: 40px;
  position: relative;
  z-index: 1;
}

.emblem {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  text-align: center;
  color: var(--color-text);
  font-size: 0.8rem;
  font-weight: 500;
}

.emblem svg {
  opacity: 0.9;
}

.about-content {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.about-content .section-title {
  margin-bottom: 20px;
}

.about-text {
  font-size: 1rem;
  color: var(--color-text-secondary);
  line-height: 1.8;
  margin-bottom: 12px;
}

.about-values {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-top: 28px;
}

.value-item {
  display: flex;
  align-items: flex-start;
  gap: 14px;
}

.value-icon {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--color-primary-light);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: 700;
  flex-shrink: 0;
  margin-top: 2px;
}

.value-item strong {
  display: block;
  font-size: 0.95rem;
  color: var(--color-text);
  margin-bottom: 2px;
}

.value-item p {
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

/* ---- Features Section ---- */
.features {
  padding: 100px 0;
  background: var(--color-surface);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 32px;
}

.feature-item {
  padding: 32px;
  border-radius: var(--radius-xl);
  border: 1px solid var(--color-border-light);
  transition: all 0.3s ease;
  position: relative;
}

.feature-item:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-md);
  transform: translateY(-4px);
}

.feature-number {
  font-family: var(--font-display);
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--color-primary-light);
  margin-bottom: 16px;
  line-height: 1;
  transition: color 0.3s ease;
}

.feature-item:hover .feature-number {
  color: var(--color-primary);
}

.feature-item h3 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--color-text);
}

.feature-item p {
  font-size: 0.925rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* ---- Contact Section ---- */
.contact {
  padding: 100px 0;
}

.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: start;
}

.contact-info .section-title {
  margin-bottom: 12px;
}

.contact-desc {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 36px;
}

.contact-items {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.contact-item {
  display: flex;
  align-items: flex-start;
  gap: 16px;
}

.contact-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  background: var(--color-primary-light);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-primary);
  flex-shrink: 0;
}

.contact-item h4 {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 4px;
}

.contact-item p {
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

/* Contact Form */
.contact-form-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-2xl);
  padding: 40px;
  box-shadow: var(--shadow-md);
}

.contact-form-card h3 {
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.contact-form-card > p {
  font-size: 0.925rem;
  color: var(--color-text-muted);
  margin-bottom: 28px;
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 8px;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 14px 16px;
  font-family: var(--font-body);
  font-size: 0.95rem;
  color: var(--color-text);
  background: var(--color-bg);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  transition: all 0.25s ease;
  outline: none;
}

.form-group input:focus,
.form-group textarea:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(26, 107, 90, 0.1);
  background: var(--color-surface);
}

.form-group input::placeholder,
.form-group textarea::placeholder {
  color: var(--color-text-muted);
}

.form-group textarea {
  resize: vertical;
  min-height: 120px;
}

/* ---- Footer ---- */
.footer {
  background: var(--color-primary-dark);
  color: rgba(255, 255, 255, 0.85);
  padding: 72px 0 32px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 48px;
  margin-bottom: 48px;
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 700;
  color: white;
  margin-bottom: 16px;
}

.footer-brand > p {
  font-size: 0.9rem;
  color: rgba(255, 255, 255, 0.6);
  line-height: 1.7;
  max-width: 300px;
}

.footer-links h4 {
  font-size: 0.925rem;
  font-weight: 600;
  color: white;
  margin-bottom: 16px;
}

.footer-links ul {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-links li,
.footer-links a {
  font-size: 0.875rem;
  color: rgba(255, 255, 255, 0.6);
  transition: color 0.25s ease;
  line-height: 1.5;
}

.footer-links a:hover {
  color: var(--color-accent);
}

.footer-bottom {
  padding-top: 28px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.825rem;
  color: rgba(255, 255, 255, 0.4);
  flex-wrap: wrap;
  gap: 12px;
}

.footer-legal {
  display: flex;
  gap: 16px;
}

/* ---- Animations ---- */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(24px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-12px); }
}

@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(1.3); }
}

@keyframes bounce {
  0%, 20%, 50%, 80%, 100% { transform: translateX(-50%) translateY(0); }
  40% { transform: translateX(-50%) translateY(-8px); }
  60% { transform: translateX(-50%) translateY(-4px); }
}

/* Scroll-triggered animations */
.animate-on-scroll {
  opacity: 0;
  transform: translateY(32px);
  transition: opacity 0.7s cubic-bezier(0.16, 1, 0.3, 1),
              transform 0.7s cubic-bezier(0.16, 1, 0.3, 1);
}

.animate-on-scroll.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ---- Responsive ---- */
@media (min-width: 1024px) {
  .hero-visual {
    display: block;
  }

  .hero-content {
    padding: 0 24px 0 max(24px, calc((100vw - var(--max-width)) / 2 + 24px));
  }
}

@media (max-width: 1023px) {
  .about-grid {
    grid-template-columns: 1fr;
    gap: 48px;
  }

  .contact-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }

  .hero-visual {
    display: none;
  }

  .hero-content {
    padding: 0 24px;
    max-width: 100%;
  }
}

@media (max-width: 768px) {
  .nav-links {
    position: fixed;
    top: 0;
    right: -100%;
    width: 280px;
    height: 100dvh;
    flex-direction: column;
    background: var(--color-surface);
    padding: 100px 32px 40px;
    box-shadow: var(--shadow-xl);
    transition: right 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    gap: 4px;
  }

  .nav-links.active {
    right: 0;
  }

  .nav-link {
    width: 100%;
    padding: 12px 16px;
    font-size: 1rem;
  }

  .nav-toggle {
    display: flex;
  }

  .nav-toggle.active span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
  }
  .nav-toggle.active span:nth-child(2) {
    opacity: 0;
  }
  .nav-toggle.active span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
  }

  .hero-stats {
    gap: 20px;
    flex-wrap: wrap;
  }

  .stat-divider {
    display: none;
  }

  .services-grid {
    grid-template-columns: 1fr;
  }

  .features-grid {
    grid-template-columns: 1fr;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }

  .about-emblems {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .contact-form-card {
    padding: 28px 24px;
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: 2rem;
  }

  .hero-actions {
    flex-direction: column;
  }

  .hero-actions .btn {
    width: 100%;
    justify-content: center;
  }

  .section-title {
    font-size: 1.75rem;
  }

  .about-image-placeholder {
    aspect-ratio: 1/1;
  }
}

/* ---- Focus & Accessibility ---- */
:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  html {
    scroll-behavior: auto;
  }
}

/* ---- Back to top ---- */
.back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--color-primary);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  cursor: pointer;
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  z-index: 999;
}

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

.back-to-top:hover {
  background: var(--color-primary-dark);
  transform: translateY(-4px);
}