:root {
  /* Professional Deep Blue Palette */
  --bg-deep: #0f172a;       /* Deep Navy Slate */
  --card-bg: #1e293b;       /* Lighter Slate for the top bar */
  --primary: #38bdf8;       /* Bright Sky Blue for actions */
  --accent: #818cf8;        /* Soft Indigo for hover */
  --text-main: #f1f5f9;     /* Off-white for comfort */
}

body {
  margin: 0;
  font-family: 'Inter', system-ui, sans-serif;
  background-color: var(--bg-deep); /* Professional Blue Background */
  color: var(--text-main);
  min-height: 100vh;
}

/* The Top Bar */
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 24px;
  background: var(--card-bg);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.3);
  position: sticky;
  top: 0;
  z-index: 1000;
}

h3 {
  margin: 0;
  font-size: 1.2rem;
  color: var(--primary);
  font-weight: 700;
  letter-spacing: -0.025em;
}

.top-bar-items {
  display: flex;
  gap: 12px;
  align-items: center;
}

/* User Action Elements */
button, .button {
  background: var(--primary);
  color: var(--bg-deep); /* Dark text on light button for contrast */
  border: none;
  padding: 10px 18px;
  border-radius: 6px;
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.2s ease;
}

button:hover, .button:hover {
  background: var(--accent);
  color: white;
  transform: translateY(-1px);
}

/* Professional Select Box */
.select {
  background: var(--bg-deep);
  border: 1px solid rgba(255, 255, 255, 0.2);
  padding: 8px 12px;
  border-radius: 6px;
  color: var(--text-main);
  font-size: 0.9rem;
  outline: none;
}

.select:focus {
  border-color: var(--primary);
}

.main-content {
  padding: 40px 20px;
  max-width: 900px;
  margin: 0 auto;
}