:root {
  --primary-color: #2196f3;
  --background-color: #ffffff;
  --text-color: #333333;
  --container-bg: rgba(255, 255, 255, 0.95);
  --input-bg: #ffffff;
  --input-border: #cccccc;
  --button-hover: #1976d2;
  --result-bg: rgba(255, 255, 255, 0.9);
}

/* Dark theme */
.dark-theme {
  --primary-color: #64b5f6;
  --background-color: #121212;
  --text-color: #ffffff;
  --container-bg: rgba(45, 45, 45, 0.95);
  --input-bg: #333333;
  --input-border: #444444;
  --button-hover: #90caf9;
  --result-bg: rgba(45, 45, 45, 0.9);
}

body {
  margin: 0;
  padding: 0;
  min-height: 100vh;
  background-color: var(--background-color);
  color: var(--text-color);
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  transition: all 0.3s ease;
}

.container {
  max-width: 600px;
  margin: 2rem auto;
  padding: 2rem;
  background-color: var(--container-bg);
  border-radius: 15px;
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.1);
  backdrop-filter: blur(10px);
}

.description {
  text-align: center;
  margin-bottom: 2rem;
  color: var(--text-color);
  font-size: 1.1rem;
}

.form-group {
  margin-bottom: 1.5rem;
}

.health-form {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

h1 {
  color: var(--text-color);
  text-align: center;
  margin-bottom: 1rem;
  font-size: 2.5rem;
  text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.1);
}

input,
select {
  width: 100%;
  padding: 12px;
  margin: 8px 0;
  border: 2px solid var(--input-border);
  border-radius: 8px;
  background-color: var(--input-bg);
  color: var(--text-color);
  transition: all 0.3s ease;
  font-size: 1rem;
}

input:focus,
select:focus {
  border-color: var(--primary-color);
  outline: none;
}

label {
  color: var(--text-color);
  font-weight: 600;
  font-size: 1.1rem;
}

.analyze-btn {
  background-color: var(--primary-color);
  color: white;
  padding: 14px 28px;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  width: 100%;
  font-size: 1.1rem;
  font-weight: bold;
  transition: all 0.3s ease;
  margin-top: 1rem;
}

.analyze-btn:hover {
  background-color: var(--button-hover);
  transform: translateY(-2px);
}

.theme-switch {
  position: fixed;
  top: 20px;
  right: 20px;
  background-color: var(--primary-color);
  color: white;
  padding: 12px 24px;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  font-size: 1rem;
  font-weight: bold;
  transition: all 0.3s ease;
}

.result {
  margin-top: 2rem;
  padding: 1.5rem;
  border-radius: 8px;
  background-color: var(--result-bg);
}

.result p {
  margin: 0.8rem 0;
  line-height: 1.6;
  font-size: 1.1rem;
}

.result strong {
  color: var(--primary-color);
}

.background-image {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
}

.fitness-background {
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.15;
  transition: opacity 0.3s ease;
}

.dark-theme .fitness-background {
  opacity: 0.1;
}

/* Responsive design */
@media (max-width: 768px) {
  .container {
    margin: 1rem;
    padding: 1.5rem;
  }

  h1 {
    font-size: 2rem;
  }

  .theme-switch {
    top: 10px;
    right: 10px;
    padding: 10px 20px;
  }
}