:root {
  --header-bg: linear-gradient(135deg, #2c3e50, #34495e);
  --calc-bg: #ffffff;
  --btn-bg: #2563eb;
}

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

body {
  font-family: 'Segoe UI', sans-serif;
  background: #f3f4f6;
  line-height: 1.6;
}

.header,
.footer {
  background: var(--header-bg);
  color: white;
  padding: 1rem;
  text-align: center;
}

.nav {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-links {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.nav a,
.footer a {
  color: white;
  text-decoration: none;
  font-size: 0.95rem;
}

.logo {
  font-size: 1.5rem;
  font-weight: bold;
}

.calculator-wrapper {
  max-width: 800px;
  margin: 2rem auto;
  padding: 20px;
}

.calc-title {
  text-align: center;
  font-size: 1.8rem;
  color: #2c3e50;
  margin-bottom: 1.5rem;
}

.calculator-container {
  display: flex;
  justify-content: center;
}

.calculator {
  background: var(--calc-bg);
  border-radius: 10px;
  padding: 2rem;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
  width: 100%;
  max-width: 600px;
  border: 1px solid #e5e7eb;
  text-align: center;
}

.calculator input {
  padding: 0.5rem;
  margin: 0.5rem;
  width: 70px;
  text-align: center;
}

.saq-row {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 1.5rem;
  margin-top: 0.5rem;
  margin-bottom: 1rem;
}

.saq-group {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.saq-group span {
  margin-bottom: 0.3rem;
  font-weight: 500;
}

.saq-group input {
  width: 60px;
  padding: 0.4rem;
  text-align: center;
}

.upload-btn {
  background: var(--btn-bg);
  color: white;
  padding: 0.8rem 1.5rem;
  border-radius: 6px;
  font-size: 1rem;
  border: none;
  cursor: pointer;
  margin-top: 1rem;
  transition: background 0.3s ease-in-out;
}

.upload-btn:hover {
  background: #1d4ed8;
}

.how-to-use,
.disclaimer {
  background: #fefce8;
  border: 1px solid #fcd34d;
  padding: 1.5rem;
  margin-top: 2rem;
  border-radius: 8px;
}

.how-to-use h2,
.disclaimer h2 {
  color: #92400e;
  margin-bottom: 1rem;
}

ul {
  padding-left: 1.2rem;
  margin: 1rem 0;
}

.footer-links {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 1rem;
}

.footer-links a {
  color: white;
  text-decoration: none;
  font-size: 0.9rem;
}