:root {
  --primary-color: #2563eb;
  --primary-hover: #1d4ed8;
  --bg-color: #f8fafc;
  --surface-color: #ffffff;
  --text-color: #1e293b;
  --text-secondary: #64748b;
  --border-color: #e2e8f0;
  --danger-color: #ef4444;
  --success-color: #22c55e;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: "Inter", sans-serif;
  background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
  color: var(--text-color);
  line-height: 1.5;
}

.app-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 20px;
  height: 100vh;
  display: flex;
  flex-direction: column;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  padding: 16px 24px;
  border-radius: 12px;
  box-shadow:
    0 4px 6px -1px rgba(0, 0, 0, 0.1),
    0 2px 4px -1px rgba(0, 0, 0, 0.06);
  border: 1px solid rgba(255, 255, 255, 0.3);
}

header h1 {
  font-size: 1.25rem;
  font-weight: 600;
}

nav {
  display: flex;
  gap: 12px;
}

.nav-btn {
  background: none;
  border: none;
  padding: 8px 16px;
  border-radius: 6px;
  cursor: pointer;
  font-weight: 500;
  color: var(--text-secondary);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
}

.nav-btn::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 6px;
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--primary-hover)
  );
  opacity: 0;
  transition: opacity 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  z-index: -1;
}

.nav-btn.active::before {
  opacity: 1;
}

.nav-btn.active {
  color: white;
  box-shadow: 0 4px 6px -1px rgba(37, 99, 235, 0.3);
  transform: translateY(-1px);
}

.nav-btn:hover:not(.active) {
  background-color: var(--border-color);
  transform: translateY(-1px);
}

.tab-content {
  display: none;
  flex: 1;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  border-radius: 12px;
  box-shadow:
    0 10px 15px -3px rgba(0, 0, 0, 0.1),
    0 4px 6px -2px rgba(0, 0, 0, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.3);
  overflow: hidden;
  padding: 24px;
  animation: fadeIn 0.3s ease-in-out;
}

.tab-content.active {
  display: flex;
  flex-direction: column;
}

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

.toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

.toolbar h2 {
  font-size: 1.25rem;
  font-weight: 600;
}

.primary-btn {
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--primary-hover)
  );
  color: white;
  border: none;
  padding: 10px 20px;
  border-radius: 6px;
  cursor: pointer;
  font-weight: 500;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 4px 6px -1px rgba(37, 99, 235, 0.3);
}

.primary-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 12px -1px rgba(37, 99, 235, 0.4);
}

.primary-btn:active {
  transform: translateY(0);
}

/* Responsive adjustments */
@media (max-width: 768px) {
  .app-container {
    padding: 10px;
  }

  header {
    flex-direction: column;
    gap: 12px;
    padding: 12px 16px;
  }

  nav {
    width: 100%;
    justify-content: center;
  }

  .nav-btn {
    padding: 6px 12px;
    font-size: 0.875rem;
  }

  .tab-content {
    padding: 16px;
  }
}