.tool-main-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: 1.25rem;
  max-width: 400px;
  margin: 0 auto;
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  box-shadow: var(--shadow-base);
  position: relative;
  overflow: hidden;
}

.converter-panel {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  position: relative;
  z-index: 1;
}

.panel-section {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.section-label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-base);
  opacity: 0.7;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.input-unit-group {
  display: flex;
  gap: 0.5rem;
}

.depth-input {
  flex: 1;
  padding: 0.65rem 0.75rem;
  background: var(--bg-page);
  border: 1px solid var(--border-base);
  border-radius: 0.75rem;
  color: var(--text-base);
  font-size: 1rem;
  font-weight: 700;
  transition: border-color 0.2s;
  box-sizing: border-box;
  -moz-appearance: textfield;
}

.depth-input::-webkit-inner-spin-button,
.depth-input::-webkit-outer-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

.depth-input:focus {
  outline: none;
  border-color: var(--accent);
}

.unit-select {
  min-width: 8rem;
  padding: 0.65rem 0.75rem;
  background: var(--bg-page);
  border: 1px solid var(--border-base);
  border-radius: 0.75rem;
  color: var(--text-base);
  font-size: 0.8125rem;
  cursor: pointer;
  transition: border-color 0.2s;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24'%3E%3Cpath fill='%23888' d='M7 10l5 5 5-5z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.6rem center;
  padding-right: 1.75rem;
}

.unit-select:focus {
  outline: none;
  border-color: var(--accent);
}

.conversions-card {
  background: var(--bg-page);
  border: 1px solid var(--border-base);
  border-radius: 1rem;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.conversions-header {
  font-size: 0.7rem;
  font-weight: 600;
  color: var(--text-base);
  opacity: 0.5;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.conversions-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem;
}

.conv-item {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
  padding: 0.4rem 0.5rem;
  background: var(--bg-surface);
  border-radius: 0.5rem;
}

.conv-label {
  font-size: 0.65rem;
  color: var(--text-base);
  opacity: 0.5;
  font-weight: 600;
  text-transform: uppercase;
}

.conv-value {
  font-size: 1rem;
  font-weight: 800;
  color: var(--accent);
  letter-spacing: -0.01em;
  font-variant-numeric: tabular-nums;
}

.rating-badge {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.25rem;
  padding: 0.75rem;
  background: linear-gradient(135deg, color-mix(in srgb, var(--accent) 10%, transparent), color-mix(in srgb, var(--accent) 5%, transparent));
  border: 1px solid color-mix(in srgb, var(--accent) 20%, var(--border-base));
  border-radius: 1rem;
}

.rating-label {
  font-size: 0.65rem;
  font-weight: 600;
  color: var(--text-base);
  opacity: 0.5;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.rating-name {
  font-size: 1.125rem;
  font-weight: 800;
  color: var(--accent);
  text-align: center;
}

.usage-cards {
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
}

.usage-card {
  display: flex;
  align-items: flex-start;
  gap: 0.625rem;
  padding: 0.625rem 0.75rem;
  background: var(--bg-page);
  border: 1px solid var(--border-base);
  border-radius: 0.75rem;
  opacity: 0.35;
  transition: all 0.3s ease;
}

.usage-card.active {
  opacity: 1;
  background: var(--bg-surface);
  border-color: var(--accent);
  box-shadow: 0 0 0 1px var(--accent);
}

.usage-icon {
  flex-shrink: 0;
  width: 1.5rem;
  height: 1.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  background: color-mix(in srgb, var(--accent) 15%, transparent);
  border-radius: 50%;
  color: var(--accent);
  margin-top: 0.05rem;
}

.usage-title {
  font-size: 0.8125rem;
  font-weight: 700;
  color: var(--text-base);
  margin-bottom: 0.1rem;
}

.usage-desc {
  font-size: 0.7rem;
  color: var(--text-base);
  opacity: 0.6;
  line-height: 1.35;
}

.tip-row {
  display: flex;
  gap: 0.5rem;
  padding: 0.75rem 1rem;
  background: var(--bg-page);
  border-radius: 0.75rem;
  border: 1px solid var(--border-base);
}

.tip-icon {
  flex-shrink: 0;
  margin-top: 0.1rem;
  color: var(--accent);
}

.tip-text {
  font-size: 0.8rem;
  color: var(--text-base);
  opacity: 0.85;
  line-height: 1.5;
}

@media (max-width: 520px) {
  .tool-main-card {
    padding: 1rem;
  }

  .input-unit-group {
    flex-direction: column;
  }

  .unit-select {
    min-width: 100%;
  }
}