body {
  font-family: "Roboto", sans-serif;
}

.main-container h1,
.main-container h2 {
  font-family: "Roboto", sans-serif;
  font-weight: 700;
}

.main-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 2rem 1rem;
}
.main-container .page-header {
  margin-bottom: 1rem;
  text-align: center;
}
.main-container .page-header h1 {
  font-size: 2rem;
  margin: 0 0 0.5rem;
}
.main-container .page-sub {
  color: #444;
  margin: 0 auto 1.25rem;
  max-width: 720px;
}

/* Panels */
.main-container .panel {
  background: #fff;
  border-radius: 14px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.06);
  padding: 1.25rem;
  margin: 1rem 0;
}
.main-container .panel h2 {
  font-size: 1.25rem;
  margin: 0 0 0.75rem;
}
.main-container .hint {
  font-size: 0.9rem;
  color: #555;
}

/* Grid for field matrix */
.main-container .grid {
  display: grid;
  gap: 1rem;
}
.main-container .cols-2 {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}
.main-container .cols-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}
.main-container .cols-4 {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}
@media (max-width: 900px) {
  .main-container .cols-4 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}
@media (max-width: 600px) {
  .main-container .cols-4,
  .main-container .cols-3,
  .main-container .cols-2 {
    grid-template-columns: 1fr;
  }
}

.main-container .field {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  background: #fafafa;
  border: 1px solid #eee;
  border-radius: 12px;
  padding: 0.9rem;
}
.main-container .field label {
  font-weight: 600;
  color: #222;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}
.main-container .unit-tag {
  font-size: 0.75rem;
  background: #eef5ff;
  border-radius: 999px;
  padding: 0.15rem 0.5rem;
}
.main-container .field .row {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}
.main-container .field input[type="number"],
.field input[type="text"] {
  width: 100%;
  padding: 0.65rem 0.7rem;
  border: 1px solid #ddd;
  border-radius: 10px;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
}
.main-container .field .btn {
  white-space: nowrap;
}

/* Controls row */
.main-container .controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
  margin: 0.25rem 0 0;
}
.main-container select,
.main-container .btn,
.main-container input[type="range"] {
  border-radius: 10px;
  border: 1px solid #ddd;
  padding: 0.55rem 0.7rem;
  background: #fff;
}
.main-container .btn {
  cursor: pointer;
  transition: transform 0.12s ease, box-shadow 0.12s ease;
}
.main-container .btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 3px 10px rgba(0, 0, 0, 0.07);
}
.main-container .btn.primary {
  background: #0f62fe;
  color: #fff;
  border-color: #0f62fe;
}
.main-container .btn.secondary {
  background: #f3f6ff;
}
.main-container .btn.ghost {
  background: #fff;
}

/* Quick converter */
.split {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 1rem;
}
@media (max-width: 800px) {
  .split {
    grid-template-columns: 1fr;
  }
}

/* Formula card */
.formula {
  background: #f9fbff;
  border: 1px solid #e6eeff;
  border-radius: 12px;
  padding: 0.9rem;
}
.formula code {
  background: #eef4ff;
  border-radius: 6px;
  padding: 0.1rem 0.3rem;
}

/* SEO/info block */
.tool-seo {
  margin: 2rem 0;
  padding: 1.5rem;
  background: #fafafa;
  border-radius: 12px;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.06);
  line-height: 1.65;
}
.tool-seo h2 {
  font-size: 1.3rem;
  margin: 0.25rem 0 0.5rem;
  border-left: 4px solid #0f62fe;
  padding-left: 0.5rem;
}
.tool-seo h3 {
  font-size: 1.05rem;
  margin: 1rem 0 0.5rem;
}
.tool-seo p {
  color: #444;
  margin: 0.6rem 0;
}
.tool-seo ul {
  list-style: disc inside;
  margin: 0.4rem 0 1rem;
}
.tool-seo li {
  margin: 0.25rem 0;
}

/* Utility */
.row {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}
.muted {
  color: #666;
}
.mono {
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
}
.copy-btn {
  padding: 0.45rem 0.6rem;
  border: 1px solid #ddd;
  border-radius: 8px;
  background: #fff;
  cursor: pointer;
}