.app-container {
  max-width: 1200px;
  margin: 2rem auto;
  padding: 0 1.5rem;
}

.intro-section {
  margin-bottom: 2rem;
  color: var(--text-muted);
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  background: var(--card-bg);
  padding: 2rem;
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border-color);
}

.intro-image {
  max-width: 100%;
  height: auto;
  max-height: 250px;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  object-fit: contain;
}

.intro-text p {
  line-height: 1.6;
  margin: 0;
  font-size: 1.1rem;
}

.calculator-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
}

@media (min-width: 992px) {
  .intro-section {
    flex-direction: row;
    text-align: left;
    padding: 2.5rem;
    gap: 3rem;
  }
  .intro-image-wrapper {
    flex: 0 0 240px;
  }
  .intro-image {
    max-height: 240px;
    width: 100%;
  }
  .calculator-grid {
    grid-template-columns: 5fr 4fr;
  }
}

.input-row {
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem;
  margin-bottom: 0.5rem;
  transition: border-color 0.2s ease;
}

.input-row:focus-within {
  border-color: var(--primary-color);
}

.input-wrapper {
  display: flex;
  align-items: center;
  margin-top: 0.5rem;
}

.input-wrapper .form-control {
  flex: 1;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  padding: 0.5rem 0.75rem;
  font-size: 1rem;
  background: var(--card-bg);
  color: var(--text-main);
  text-align: right;
  transition: all 0.2s ease;
}

.input-wrapper .form-control:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.input-wrapper .input-suffix {
  margin-left: 0.75rem;
  font-weight: 600;
  color: var(--text-main);
}

.input-wrapper .prefix-label {
  width: 100px;
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-right: 0.5rem;
}

.result-card-item {
  background: var(--bg-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  text-align: center;
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
}

.result-value {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.result-label {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-muted);
}

.evaluate-btn {
  background: linear-gradient(135deg, var(--primary-color), #2563eb);
  color: #fff;
  border: none;
  border-radius: var(--radius-full, 9999px);
  padding: 1.25rem 2rem;
  font-size: 1.25rem;
  font-weight: 800;
  cursor: pointer;
  width: 100%;
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.3);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.evaluate-btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 10px 20px rgba(37, 99, 235, 0.4);
  background: linear-gradient(135deg, #2563eb, var(--primary-color));
}

.evaluate-btn:active {
  transform: translateY(1px);
  box-shadow: 0 2px 5px rgba(37, 99, 235, 0.3);
}

.btn-appendix-trigger {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  background-color: var(--bg-color);
  color: var(--primary-color);
  border: 1px solid var(--primary-color);
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  box-shadow: 0 1px 3px rgba(0,0,0,0.05);
}

.btn-appendix-trigger:hover {
  background-color: var(--primary-color);
  color: #ffffff;
  box-shadow: 0 4px 6px rgba(37, 99, 235, 0.2);
}

.btn-appendix-trigger:active {
  transform: translateY(1px);
}