:root {
  --primary: #667eea;
  --primary-dark: #764ba2;
  --text: #2c3e50;
  --text-light: #7f8c8d;
  --bg: #f5f7fa;
  --card-bg: #ffffff;
  --border: #e1e8ed;
  --shadow: rgba(0, 0, 0, 0.08);
  --hover-shadow: rgba(102, 126, 234, 0.2);
}

* {
  box-sizing: border-box;
}

body {
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  transition: all 0.3s ease;
}

.ui-style-0 { --primary: #ff6b6b; --primary-dark: #ee5a52; }
.ui-style-1 { --primary: #4ecdc4; --primary-dark: #44a3a0; }
.ui-style-2 { --primary: #95e1d3; --primary-dark: #69d2c2; }
.ui-style-3 { --primary: #f38181; --primary-dark: #e66767; }
.ui-style-4 { --primary: #aa96da; --primary-dark: #9785c7; }
.ui-style-5 { --primary: #fcbad3; --primary-dark: #f9a2c4; }
.ui-style-6 { --primary: #a8d8ea; --primary-dark: #8fc9dd; }
.ui-style-7 { --primary: #667eea; --primary-dark: #764ba2; }
.ui-style-8 { --primary: #fa8231; --primary-dark: #e87527; }
.ui-style-9 { --primary: #7bed9f; --primary-dark: #69d98f; }
.ui-style-10 { --primary: #ffd32a; --primary-dark: #f0c520; }
.ui-style-11 { --primary: #ff7675; --primary-dark: #eb6563; }
.ui-style-12 { --primary: #a29bfe; --primary-dark: #9189f0; }
.ui-style-13 { --primary: #74b9ff; --primary-dark: #5fa8f7; }
.ui-style-14 { --primary: #fd79a8; --primary-dark: #f96499; }
.ui-style-15 { --primary: #fdcb6e; --primary-dark: #f5bd5b; }

button, .btn {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: white;
  border: none;
  padding: 0.75rem 1.5rem;
  border-radius: 6px;
  cursor: pointer;
  font-weight: 500;
  transition: all 0.3s;
}

button:hover, .btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px var(--hover-shadow);
}

.highlight-box {
  background: linear-gradient(135deg, rgba(102, 126, 234, 0.1) 0%, rgba(118, 75, 162, 0.1) 100%);
  border-left: 4px solid var(--primary);
  padding: 1rem;
  border-radius: 4px;
  margin: 1rem 0;
}

.card {
  background: var(--card-bg);
  border-radius: 8px;
  padding: 1.5rem;
  box-shadow: 0 2px 12px var(--shadow);
  transition: all 0.3s;
}

.card:hover {
  box-shadow: 0 4px 20px var(--hover-shadow);
  transform: translateY(-4px);
}

@media (max-width: 768px) {
  body {
    font-size: 14px;
  }

  .card {
    padding: 1rem;
  }
}

@media (max-width: 480px) {
  body {
    font-size: 13px;
  }
}

.fade-in {
  animation: fadeIn 0.5s ease-in;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  background: var(--primary);
  color: white;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  opacity: 0;
  transition: all 0.3s;
  box-shadow: 0 4px 12px var(--shadow);
  z-index: 1000;
}

.back-to-top.visible {
  opacity: 1;
}

.back-to-top:hover {
  transform: translateY(-5px);
  box-shadow: 0 6px 20px var(--hover-shadow);
}