:root {
      /* Warm amber palette */
      --bg-dark: #0b0906; /* near-black warm */
      --bg-mid: #16100a;  /* deep brown */
      --bg-light: #21160d; /* brown-black */
      --accent: #ffb300;  /* amber */
      --accent-soft: rgba(255, 179, 0, 0.18);
      --text-main: #fff7e6; /* warm off-white */
      --text-muted: #cbbda3; /* desaturated warm */
      --card-bg: rgba(22, 14, 9, 0.88);
      --border: rgba(255, 179, 0, 0.22);
      --shadow: 0 25px 60px rgba(0, 0, 0, 0.5);
    }

    * {
      box-sizing: border-box;
    }

    img, video {
      max-width: 100%;
      height: auto;
    }

    .visually-hidden {
      position: absolute;
      width: 1px;
      height: 1px;
      padding: 0;
      margin: -1px;
      overflow: hidden;
      clip: rect(0, 0, 0, 0);
      border: 0;
    }

    body {
      margin: 0;
      min-height: 100vh;
      font-family: "Space Grotesk", "Segoe UI", system-ui, -apple-system, sans-serif;
      background: radial-gradient(circle at 18% 18%, rgba(255, 179, 0, 0.10), transparent 46%),
                  radial-gradient(circle at 82% 0%, rgba(255, 128, 0, 0.18), transparent 56%),
                  linear-gradient(135deg, var(--bg-dark), var(--bg-mid) 52%, var(--bg-light));
      color: var(--text-main);
      display: flex;
      justify-content: center;
      align-items: flex-start;
      padding: 60px 20px 120px;
    }

    main {
      width: min(1100px, 100%);
      backdrop-filter: blur(12px);
      background: var(--card-bg);
      border: 1px solid var(--border);
      border-radius: 32px;
      box-shadow: var(--shadow);
      overflow: hidden;
    }

    header {
      position: relative;
      padding: 60px clamp(2rem, 5vw, 4rem) 40px;
      background: linear-gradient(135deg, rgba(255, 179, 0, 0.12), rgba(255, 128, 0, 0.06));
    }

    header::after {
      content: "";
      position: absolute;
      inset: 0;
      background: radial-gradient(circle at 85% 15%, rgba(255, 179, 0, 0.25), transparent 55%);
      mix-blend-mode: screen;
      pointer-events: none;
    }

    .logo-wrap {
      position: relative;
      width: clamp(160px, 24vw, 240px);
      margin-bottom: 28px;
      filter: drop-shadow(0 18px 40px rgba(0, 0, 0, 0.45));
    }

    .logo-wrap::before {
      content: "";
      position: absolute;
      inset: -22% -14%;
      border-radius: 32px;
      background: radial-gradient(circle, rgba(255, 179, 0, 0.22), transparent 60%);
      z-index: -1;
      animation: pulse 6s ease-in-out infinite;
    }

    @keyframes pulse {
      0%, 100% { transform: scale(1); opacity: 0.9; }
      50% { transform: scale(1.05); opacity: 0.6; }
    }

    .logo-wrap img {
      width: 100%;
      display: block;
    }

    .top-bar {
      display: flex;
      justify-content: space-between;
      align-items: flex-start;
      gap: clamp(1.5rem, 4vw, 3rem);
    }

    .primary-nav {
      display: flex;
      align-items: center;
      gap: 1rem;
      font-size: 0.95rem;
    }

    .primary-nav a,
    .primary-nav summary {
      display: inline-flex;
      align-items: center;
      gap: 0.4rem;
      padding: 0.6rem 1.1rem;
      min-height: 44px; /* comfortable tap target */
      border-radius: 999px;
      border: 1px solid var(--border);
      background: rgba(18, 12, 6, 0.78);
      color: var(--text-main);
      text-decoration: none;
      cursor: pointer;
      transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
    }

    .primary-nav a:hover,
    .primary-nav a:focus-visible,
    .primary-nav summary:hover,
    .primary-nav summary:focus-visible {
      border-color: var(--accent);
      transform: translateY(-2px);
      box-shadow: 0 12px 24px rgba(255, 179, 0, 0.25);
      outline: none;
    }

    .nav-drop {
      position: relative;
    }

    .nav-drop summary {
      list-style: none;
    }

    .nav-drop summary::-webkit-details-marker {
      display: none;
    }

    .nav-drop[open] summary {
      border-color: var(--accent);
    }

    .nav-drop[open] .nav-panel {
      opacity: 1;
      transform: translateY(0);
      pointer-events: auto;
    }

    .nav-panel {
      position: absolute;
      top: calc(100% + 0.75rem);
      right: 0;
      width: clamp(260px, 28vw, 320px);
      padding: 1.4rem;
      border-radius: 18px;
      border: 1px solid var(--border);
      background: rgba(16, 10, 6, 0.95);
      box-shadow: 0 22px 40px rgba(0, 0, 0, 0.55);
      opacity: 0;
      transform: translateY(10px);
      transition: opacity 0.18s ease, transform 0.18s ease;
      pointer-events: none;
      z-index: 10;
    }

.nav-panel h3 {
  margin: 0 0 0.6rem;
  font-size: 1rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

/* Bitcoin icon badge */
.btc-icon {
  display: inline-grid;
  place-items: center;
  width: 1.25em;
  height: 1.25em;
  margin-right: 0.4rem;
  border-radius: 50%;
  border: 1px solid rgba(255, 179, 0, 0.35);
  background: linear-gradient(135deg, rgba(255, 179, 0, 0.28), rgba(255, 128, 0, 0.22));
  color: #1a1209;
  font-weight: 700;
}

    .nav-panel p,
    .nav-panel span {
      margin: 0 0 0.8rem;
      font-size: 0.95rem;
      color: var(--text-muted);
      line-height: 1.6;
    }

    .nav-panel .nav-link-card {
      display: block;
      padding: 0.8rem 1rem;
      margin: 0 0 0.9rem;
      border-radius: 12px;
      border: 1px solid var(--border);
      background: rgba(18, 12, 6, 0.78);
      color: var(--text-main);
      text-decoration: none;
      transition: border-color 0.2s ease, transform 0.2s ease, box-shadow 0.2s ease;
    }

    .nav-panel .nav-link-card:last-of-type {
      margin-bottom: 0;
    }

    .nav-panel .nav-link-card:hover,
    .nav-panel .nav-link-card:focus-visible {
      border-color: var(--accent);
      box-shadow: 0 12px 24px rgba(255, 179, 0, 0.25);
      transform: translateY(-2px);
      outline: none;
    }

    .nav-link-title {
      font-size: 0.95rem;
      font-weight: 600;
      letter-spacing: 0.02em;
    }

    .nav-link-desc {
      display: block;
      margin-top: 0.35rem;
      font-size: 0.9rem;
      color: var(--text-muted);
      line-height: 1.5;
    }

    .nav-panel .wallet {
      margin: 0;
      width: 100%;
    }

    .nav-panel .qr-card {
      margin-top: 1rem;
    }

    .tagline {
      font-size: clamp(1.1rem, 2.2vw, 1.4rem);
      max-width: 640px;
      margin: 0;
      color: var(--text-muted);
      line-height: 1.6;
    }

    .content {
      padding: clamp(2.5rem, 6vw, 4rem);
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
      gap: clamp(1.8rem, 4vw, 3rem);
    }

    section {
      background: rgba(16, 10, 6, 0.9);
      border: 1px solid rgba(255, 179, 0, 0.12);
      border-radius: 22px;
      padding: clamp(1.8rem, 4vw, 2.4rem);
      position: relative;
      overflow: hidden;
    }

    section::before {
      content: "";
      position: absolute;
      inset: -40% 35% auto -30%;
      height: 120%;
      background: radial-gradient(circle, rgba(255, 179, 0, 0.08), transparent 65%);
      opacity: 0.8;
      pointer-events: none;
    }

    .about-intro,
    .guidelines {
      grid-column: 1 / -1;
      padding: clamp(2.2rem, 5vw, 2.8rem);
      display: grid;
      gap: clamp(1.2rem, 3vw, 1.8rem);
    }

    .about-intro h2,
    .guidelines h2 {
      margin: 0;
      font-size: clamp(1.8rem, 3.2vw, 2.2rem);
      text-transform: uppercase;
      letter-spacing: 0.12em;
    }

    .about-intro p {
      margin: 0;
      color: var(--text-muted);
      line-height: 1.7;
    }

    .about-intro p + p {
      margin-top: 0.6rem;
    }

    .guidelines p {
      margin: 0;
      color: var(--text-muted);
      line-height: 1.6;
    }

    .guideline-list {
      list-style: none;
      margin: 0;
      padding: 0;
      display: grid;
      gap: 26px;
    }

    .guideline-list li {
      position: relative;
      padding-left: 0;
    }

    .guideline-list h3 {
      margin: 0 0 6px;
      font-size: 1.2rem;
      text-transform: uppercase;
      letter-spacing: 0.08em;
    }

    .guideline-list p {
      margin: 0;
      color: var(--text-muted);
      line-height: 1.6;
    }

    .wallet {
      font-family: "JetBrains Mono", "SFMono-Regular", "Menlo", monospace;
      background: rgba(18, 12, 6, 0.88);
      border: 1px solid var(--border);
      border-radius: 14px;
      padding: 16px 18px;
      font-size: 0.96rem;
      word-break: break-all;
      position: relative;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 12px;
    }

    .wallet button {
      cursor: pointer;
      border: none;
      border-radius: 10px;
      background: var(--accent);
      color: #041018;
      font-weight: 600;
      padding: 10px 16px;
      min-height: 44px;
      transition: transform 0.2s ease, box-shadow 0.2s ease;
    }

    .wallet button:hover,
    .wallet button:focus-visible {
      transform: translateY(-2px);
      box-shadow: 0 12px 24px rgba(255, 179, 0, 0.35);
      outline: none;
    }

    .wallet button:active {
      transform: translateY(0);
    }

    .wallet button[disabled] {
      cursor: wait;
      opacity: 0.7;
    }

    .qr-card {
      display: flex;
      flex-direction: column;
      gap: 14px;
    }

    .qr-card #qr-code {
      display: grid;
      place-items: center;
      border-radius: 16px;
      border: 1px solid rgba(255, 179, 0, 0.18);
      background: rgba(16, 10, 6, 0.7);
      padding: 14px;
      aspect-ratio: 1 / 1;
    }

    .qr-card canvas,
    .qr-card img {
      width: 100%;
      height: 100%;
      border-radius: 12px;
    }

    .qr-card h3 {
      margin: 0 0 10px;
      font-size: 1.25rem;
      letter-spacing: 0.05em;
    }

    footer {
      text-align: center;
      font-size: 0.88rem;
      color: var(--text-muted);
      padding: calc(32px + env(safe-area-inset-top))
               calc(1.5rem + env(safe-area-inset-right))
               calc(40px + env(safe-area-inset-bottom))
               calc(1.5rem + env(safe-area-inset-left));
      background: rgba(12, 8, 5, 0.82);
      border-top: 1px solid rgba(255, 179, 0, 0.12);
    }

    footer span {
      color: var(--accent);
    }

    footer .copyright {
      margin-top: 0.4rem;
      color: var(--text-muted);
      letter-spacing: 0.08em;
      text-transform: uppercase;
      font-size: 0.78rem;
    }

    @media (max-width: 720px) {
      body {
        padding: calc(40px + env(safe-area-inset-top))
                 calc(12px + env(safe-area-inset-right))
                 calc(80px + env(safe-area-inset-bottom))
                 calc(12px + env(safe-area-inset-left));
      }

      header {
        padding: 48px 1.8rem 32px;
      }

      .top-bar {
        flex-direction: column;
        align-items: flex-start;
        gap: 1.8rem;
      }

      .primary-nav {
        flex-wrap: wrap;
        gap: 0.8rem;
      }

      .nav-drop {
        width: 100%;
      }

      .nav-drop summary {
        width: 100%;
        justify-content: space-between;
      }

      .nav-panel {
        position: static;
        transform: none;
        opacity: 1;
        pointer-events: auto;
        width: 100%;
        margin-top: 0.8rem;
      }

      .content {
        grid-template-columns: 1fr;
        padding: 1.2rem;
      }

      section {
        border-radius: 18px;
        padding: 1.4rem;
      }
    }
    @media (prefers-reduced-motion: reduce) {
      *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
      }
    }