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

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: #f5f5f5;
  height: 100vh;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

/* Navigation Bar */
nav {
  background: #1976D2;
  color: white;
  padding: 0.5rem 1rem;
  box-shadow: 0 2px 4px rgba(0,0,0,0.2);
  z-index: 1000;
}

.nav-container {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.nav-container button {
  background: transparent;
  border: none;
  color: white;
  font-weight: bold;
  cursor: pointer;
  padding: 0.4rem 0.8rem;
  border-radius: 4px;
}

.nav-container button:hover {
  background: rgba(255,255,255,0.15);
}

.spacer {
  flex: 1;
}

#threshold-select {
  padding: 0.4rem;
  border-radius: 4px;
  border: none;
}

/* Main View */
#app-view {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.view {
  display: none;
  flex: 1;
  flex-direction: column;
  overflow: hidden;
}

.view.active {
  display: flex;
}

/* Map */
#map {
  flex: 1;
  width: 100%;
  min-height: 0;
}

/* Info Panel */
#info {
  padding: 1rem;
  background: white;
  text-align: center;
  box-shadow: 0 -2px 5px rgba(0,0,0,0.1);
  z-index: 900;
}

#distance, #status {
  margin: 0.5rem 0;
  font-size: 1.1rem;
}

.eligible { color: green; font-weight: bold; }
.not-eligible { color: red; font-weight: bold; }

/* Buttons */
button {
  margin: 0.3rem;
  padding: 0.4rem 0.8rem;
  background: #1976D2;
  color: white;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}

button:hover:not(:disabled) {
  background: #1565C0;
}

button:disabled {
  background: #bdbdbd;
  cursor: not-allowed;
}

/* About View */
.about-content {
  padding: 2rem;
  overflow-y: auto;
  line-height: 1.6;
}

.about-content h2 {
  margin-bottom: 1rem;
  color: #1976D2;
}

.about-content ul {
  margin: 0.8rem 0 1.2rem 1.5rem;
}

.about-content p {
  margin-bottom: 1rem;
}