:root {
  --primary: #10b981;
  --primary-hover: #059669;
  --secondary: #0f172a;
  --bg-color: #f8fafc;
  --card-bg: rgba(255, 255, 255, 0.8);
  --text-main: #1e293b;
  --text-muted: #64748b;
  --shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
  --glass-border: rgba(255, 255, 255, 0.2);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
}

body {
  background-color: var(--bg-color);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header & Nav */
header {
  padding: 2rem 0;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.75rem;
  font-weight: 800;
  color: var(--primary);
  letter-spacing: -0.025em;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo-icon {
  background: var(--primary);
  color: white;
  padding: 0.2rem 0.5rem;
  border-radius: 8px;
  font-size: 1.2rem;
}

.lang-toggle {
  background: var(--card-bg);
  border: 1px solid #e1e8ed;
  padding: 0.5rem 1rem;
  border-radius: 9999px;
  cursor: pointer;
  font-weight: 600;
  transition: all 0.2s ease;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.lang-toggle:hover {
  background: white;
  box-shadow: var(--shadow);
}

/* Hero Section */
.hero {
  text-align: center;
  padding: 3rem 0;
  background: radial-gradient(circle at top right, rgba(16, 185, 129, 0.05), transparent);
}

h1 {
  font-size: 3.5rem;
  font-weight: 800;
  margin-bottom: 1rem;
  letter-spacing: -0.05em;
  background: linear-gradient(to right, var(--secondary), var(--primary));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.subtitle {
  color: var(--text-muted);
  font-size: 1.25rem;
  max-width: 600px;
  margin: 0 auto 2rem;
}

/* Layout Grid */
.main-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  margin-top: 2rem;
}

@media (max-width: 850px) {
  .main-grid {
    grid-template-columns: 1fr;
  }
}

/* Cards */
.card {
  background: var(--card-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  border-radius: 24px;
  padding: 2rem;
  box-shadow: var(--shadow);
}

.card h2 {
  font-size: 1.5rem;
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

/* Forms */
.input-group {
  margin-bottom: 1.5rem;
}

label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: var(--secondary);
}

input[type="text"],
input[type="number"],
select {
  width: 100%;
  padding: 0.75rem 1rem;
  border-radius: 12px;
  border: 1px solid #e2e8f0;
  background: white;
  font-size: 1rem;
  transition: border-color 0.2s;
}

input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(16, 185, 129, 0.1);
}

.range-wrap {
  position: relative;
  margin: 1rem 0;
}

input[type=range] {
  width: 100%;
  accent-color: var(--primary);
  cursor: pointer;
}

.range-val {
  font-weight: 700;
  color: var(--primary);
}

/* Results Display */
.results-card {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.result-item {
  background: white;
  padding: 1.5rem;
  border-radius: 16px;
  border-left: 5px solid var(--primary);
  animation: fadeIn 0.5s ease-out;
}

.result-val {
  display: block;
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--secondary);
}

.result-label {
  color: var(--text-muted);
  font-weight: 600;
  font-size: 0.9rem;
  text-transform: uppercase;
}

.carbon-badge {
  display: inline-block;
  padding: 0.25rem 0.75rem;
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 700;
  margin-top: 0.5rem;
}

.low { background: #dcfce7; color: #166534; }
.medium { background: #fef9c3; color: #854d0e; }
.high { background: #fee2e2; color: #991b1b; }

/* Tips Section */
.tips-section {
  margin-top: 4rem;
  padding-bottom: 4rem;
}

.tips-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
}

.tip-card {
  background: white;
  padding: 1.5rem;
  border-radius: 16px;
  border: 1px solid #f1f5f9;
  transition: transform 0.2s;
}

.tip-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow);
}

.tip-icon {
  font-size: 1.5rem;
  margin-bottom: 1rem;
}

/* FAQ */
.faq-section {
  background: white;
  padding: 4rem 0;
  margin-top: 2rem;
}

.faq-title {
  text-align: center;
  margin-bottom: 3rem;
}

.faq-item {
  max-width: 800px;
  margin: 0 auto 1.5rem;
  border-bottom: 1px solid #f1f5f9;
  padding-bottom: 1.5rem;
}

.faq-q {
  font-weight: 700;
  font-size: 1.1rem;
  margin-bottom: 0.5rem;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.faq-a {
  color: var(--text-muted);
  padding-right: 2rem;
}

/* Footer */
footer {
  text-align: center;
  padding: 3rem 0;
  color: var(--text-muted);
  font-size: 0.9rem;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Navigation for mobile */
@media (max-width: 600px) {
  h1 { font-size: 2.5rem; }
  .main-grid { gap: 1rem; }
}