:root {
  --bg: #0f172a;          /* slate-900 */
  --panel: #111827;       /* gray-900 */
  --text: #e5e7eb;        /* gray-200 */
  --muted: #9ca3af;       /* gray-400 */
  --accent: #22d3ee;      /* cyan-400 */
}

* {
  box-sizing: border-box;
}

/* Lock page to viewport (no scrolling) */
html, body {
  height: 100%;
  margin: 0;
  overflow: hidden;
  background: radial-gradient(
    1200px 600px at 20% 10%,
    #111827 0%,
    var(--bg) 60%
  );
  color: var(--text);
  font: 16px/1.6 system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, sans-serif;
}

/* Page container */
.container {
  max-width: 860px;
  margin: 8vh auto;
  padding: 0 16px;
}

/* Headings */
h1 {
  font-size: 2.25rem;
  margin: 0 0 8px;
}

h2 {
  margin: 0 0 10px;
}

/* Card base */
.card {
  margin-top: 20px;
  background: linear-gradient(
    180deg,
    rgba(255,255,255,0.05),
    rgba(255,255,255,0.02)
  );
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 18px;
  box-shadow: 0 12px 34px rgba(0,0,0,0.4);
}

/* Inline code */
code {
  background: rgba(255,255,255,0.08);
  padding: 2px 6px;
  border-radius: 6px;
}

/* Buttons */
button {
  margin-top: 10px;
  padding: 10px 14px;
  border-radius: 12px;
  border: 1px solid rgba(255,255,255,0.16);
  background: transparent;
  color: var(--text);
  cursor: pointer;
  transition:
    transform 0.05s ease,
    box-shadow 0.15s ease,
    border-color 0.15s ease;
}

button:hover {
  border-color: var(--accent);
  box-shadow: 0 6px 22px rgba(34,211,238,0.25);
}

button:active {
  transform: translateY(1px);
}

/* Muted text */
.muted {
  color: var(--muted);
}

/* ============================
   Split card layout (FINAL)
   ============================ */
.card.split {
  display: grid;
  grid-template-columns: 1fr 1.8fr;
  gap: 36px;
  padding: 26px 30px;
  align-items: start;
}

/* Left panel text width control */
.card.split .left p {
  max-width: 260px;
}

/* Right panel separator + overflow protection */
.card.split .right {
  padding-left: 28px;
  border-left: 1px solid rgba(255,255,255,0.08);
  overflow: hidden;
}

/* Prevent long paths from breaking layout */
.card.split .right code {
  display: block;
  max-width: 100%;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* ============================
   Image block (FINAL)
   ============================ */
.image-box {
  margin: 18px auto 14px;
  padding: 18px;
  width: 260px;
  border-radius: 16px;
  background: rgba(255,255,255,0.05);
  border: 1px dashed rgba(255,255,255,0.18);
  display: flex;
  justify-content: center;
  align-items: center;
}

/* Fixed image size: 4 × 2 cm */
.image-box img {
  width: 4cm;
  height: 2cm;
  object-fit: contain;
  background: #ffffff;
  border-radius: 6px;
  padding: 6px;
  display: block;
}

/* ============================
   Responsive (mobile)
   ============================ */
@media (max-width: 720px) {
  html, body {
    overflow: auto; /* allow scroll on small screens */
  }

  .container {
    margin: 5vh auto;
  }

  .card.split {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .card.split .right {
    padding-left: 0;
    border-left: none;
  }

  .image-box {
    width: 100%;
    max-width: 260px;
  }
}