* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: #f0f7f4;
  color: #2d3748;
  line-height: 1.6;
  min-height: 100vh;
}

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 16px;
}

h1 {
  font-size: 1.4rem;
  color: #1a6b4a;
  margin-bottom: 4px;
}

.subtitle {
  font-size: 0.85rem;
  color: #6b8f7e;
  margin-bottom: 24px;
}

h2 {
  font-size: 1rem;
  color: #2d6a4f;
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.form-section,
.list-section {
  background: #fff;
  border-radius: 10px;
  padding: 20px;
  margin-bottom: 20px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}

.form-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-bottom: 14px;
}

@media (max-width: 480px) {
  .form-grid {
    grid-template-columns: 1fr;
  }
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

label {
  font-size: 0.82rem;
  font-weight: 600;
  color: #4a5568;
}

input[type="text"],
input[type="number"] {
  padding: 8px 10px;
  border: 1.5px solid #cbd5e0;
  border-radius: 6px;
  font-size: 0.95rem;
  outline: none;
  transition: border-color 0.2s;
  background: #f8fffe;
}

input[type="text"]:focus,
input[type="number"]:focus {
  border-color: #38a169;
}

.preview {
  background: #e6f4ed;
  border-radius: 8px;
  padding: 12px 16px;
  margin-bottom: 14px;
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
}

.preview-item {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.preview-label {
  font-size: 0.78rem;
  color: #2d6a4f;
  font-weight: 600;
}

.preview-value {
  font-size: 1.1rem;
  font-weight: 700;
  color: #1a6b4a;
}

.btn-add {
  width: 100%;
  padding: 11px;
  background: #38a169;
  color: #fff;
  border: none;
  border-radius: 7px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s;
}

.btn-add:hover {
  background: #2f855a;
}

.count-badge {
  background: #38a169;
  color: #fff;
  border-radius: 12px;
  padding: 1px 8px;
  font-size: 0.78rem;
  font-weight: 700;
}

.empty-msg {
  color: #a0aec0;
  text-align: center;
  padding: 24px 0;
  font-size: 0.9rem;
}

.device-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.device-card {
  border: 1.5px solid #c6f6d5;
  border-radius: 8px;
  padding: 14px;
  background: #f0fff4;
  position: relative;
}

.device-card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 10px;
}

.device-name {
  font-weight: 700;
  font-size: 1rem;
  color: #1a6b4a;
}

.btn-delete {
  background: none;
  border: none;
  color: #fc8181;
  cursor: pointer;
  font-size: 1.1rem;
  padding: 2px 6px;
  border-radius: 4px;
  transition: background 0.15s;
  line-height: 1;
}

.btn-delete:hover {
  background: #fff5f5;
}

.device-metrics {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
}

@media (max-width: 420px) {
  .device-metrics {
    grid-template-columns: 1fr;
  }
}

.metric {
  background: #fff;
  border-radius: 6px;
  padding: 8px 10px;
}

.metric-label {
  font-size: 0.73rem;
  color: #6b8f7e;
  font-weight: 600;
}

.metric-value {
  font-size: 0.95rem;
  font-weight: 700;
  color: #2d6a4f;
  margin-top: 2px;
}

.metric-value.highlight {
  color: #1a6b4a;
  font-size: 1.05rem;
}

.payback-good {
  color: #276749;
}

.payback-mid {
  color: #c05621;
}

.payback-bad {
  color: #c53030;
}