* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  /* Backgrounds */
  --bg: #f8fafc;
  --bg-secondary: #ffffff;

  /* Brand */
  --primary: #334155;
  --secondary: #64748b;

  /* Text */
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;

  /* Text on colored backgrounds */
  --text-on-primary: #ffffff;
  --text-on-secondary: #ffffff;

  /* Border */
  --border: #e2e8f0;

  /* Gradient */
  --gradient: linear-gradient(135deg, #ffffff 0%, #f8fafc 50%, #eef2f7 100%);

  /* Shadow */
  --shadow: 0 8px 30px rgba(15, 23, 42, 0.08);

  --font-heading: "Merriweather", serif;
  --font-body: "Manrope", sans-serif;
}

body {
  font-family: var(--font-body);
  background: var(--bg);
  min-height: 100vh;
}

/* Chrome, Edge, Safari */

::-webkit-scrollbar {
  width: 10px;
  height: 10px;
}

::-webkit-scrollbar-track {
  background: #f8fafc;
}

::-webkit-scrollbar-thumb {
  background: #cbd5e1;
  border-radius: 999px;
  border: 2px solid #f8fafc;
}

::-webkit-scrollbar-thumb:hover {
  background: #94a3b8;
}

::-webkit-scrollbar-corner {
  background: #f8fafc;
}

/* Firefox */

* {
  scrollbar-width: thin;
  scrollbar-color: #cbd5e1 #f8fafc;
}

.scroll-top-btn {
  position: fixed;

  right: 24px;
  bottom: 24px;

  width: 52px;
  height: 52px;

  border: none;

  border-radius: 50%;

  background: var(--primary);

  color: var(--text-on-primary);

  font-size: 1.2rem;
  font-weight: 700;

  cursor: pointer;

  display: flex;
  align-items: center;
  justify-content: center;

  box-shadow: 0 12px 30px rgba(51, 65, 85, 0.18);

  opacity: 0;
  visibility: hidden;

  transform: translateY(20px);

  transition:
    opacity 0.3s ease,
    visibility 0.3s ease,
    transform 0.3s ease;

  z-index: 999;
}

.scroll-top-btn.show {
  opacity: 1;
  visibility: visible;

  transform: translateY(0);
}

.scroll-top-btn:hover {
  transform: translateY(-4px);

  box-shadow: 0 18px 40px rgba(51, 65, 85, 0.25);
}

.scroll-top-btn:active {
  transform: translateY(-2px);
}

@media (max-width: 768px) {
  .scroll-top-btn {
    width: 46px;
    height: 46px;

    right: 16px;
    bottom: 16px;
  }
}