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

body {
	font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
	line-height: 1.6;
	color: #333;
	background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
	min-height: 100vh;
	padding: 20px;
}

.container {
	max-width: 1200px;
	margin: 0 auto;
	background: rgba(255, 255, 255, 0.95);
	border-radius: 20px;
	box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
	overflow: hidden;
}

.header {
	background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
	padding: 30px;
	text-align: center;
	color: white;
}

.header h1 {
	font-size: 2.5em;
	margin-bottom: 10px;
}

.content {
	padding: 30px;
}

.lesson {
	background: white;
	border-radius: 15px;
	padding: 25px;
	margin-bottom: 25px;
	box-shadow: 0 5px 15px rgba(0, 0, 0, 0.08);
	border-left: 5px solid #4facfe;
}

.lesson h2 {
	color: #4facfe;
	margin-bottom: 15px;
	font-size: 1.5em;
}

.example {
	background: #f8f9fa;
	border-radius: 10px;
	padding: 20px;
	margin: 15px 0;
	border-left: 4px solid #28a745;
}

.code {
	background: #1e1e1e;
	color: #d4d4d4;
	padding: 15px;
	border-radius: 8px;
	font-family: "Monaco", "Menlo", "Ubuntu Mono", monospace;
	font-size: 14px;
	margin: 10px 0;
	overflow-x: auto;
}

.sql-keyword {
	color: #569cd6;
	font-weight: bold;
}

.sql-string {
	color: #ce9178;
}

.sql-number {
	color: #b5cea8;
}

.playground {
	background: #f0f8ff;
	border-radius: 15px;
	padding: 25px;
	margin: 25px 0;
	border: 2px solid #4facfe;
}

.playground h3 {
	color: #4facfe;
	margin-bottom: 15px;
}

.data-preview {
	background: white;
	border-radius: 10px;
	padding: 20px;
	margin: 15px 0;
	border: 1px solid #ddd;
}

table {
	width: 100%;
	border-collapse: collapse;
	margin: 10px 0;
	background: white;
	border-radius: 8px;
	overflow: hidden;
	box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

th {
	background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
	color: white;
	padding: 12px;
	text-align: left;
	font-weight: bold;
}

td {
	padding: 12px;
	border-bottom: 1px solid #eee;
}

tr:nth-child(even) {
	background-color: #f8f9fa;
}

tr:hover {
	background-color: #e8f4fd;
}

input[type="text"],
textarea {
	width: 100%;
	padding: 12px;
	border: 2px solid #ddd;
	border-radius: 8px;
	font-size: 16px;
	margin: 8px 0;
	transition: border-color 0.3s;
	font-family: "Monaco", "Menlo", "Ubuntu Mono", monospace;
}

input[type="text"]:focus,
textarea:focus {
	outline: none;
	border-color: #4facfe;
}

button {
	background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
	color: white;
	border: none;
	padding: 12px 25px;
	border-radius: 25px;
	cursor: pointer;
	font-size: 16px;
	margin: 5px;
	transition: transform 0.2s, box-shadow 0.2s;
}

button:hover {
	transform: translateY(-2px);
	box-shadow: 0 5px 15px rgba(79, 172, 254, 0.4);
}

.result {
	background: #e8f5e8;
	border-radius: 8px;
	padding: 15px;
	margin-top: 15px;
	border-left: 4px solid #28a745;
}

.error {
	background: #ffe6e6;
	border-left-color: #dc3545;
	color: #721c24;
}

.section {
	margin-bottom: 30px;
}

.quick-ref {
	background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
	color: white;
	border-radius: 15px;
	padding: 25px;
	margin: 25px 0;
}

.quick-ref h3 {
	margin-bottom: 15px;
}

.ref-grid {
	display: grid;
	grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
	gap: 15px;
	margin-top: 15px;
}

.ref-item {
	background: rgba(255, 255, 255, 0.1);
	padding: 10px;
	border-radius: 8px;
}

.ref-item strong {
	color: #ffeb3b;
}

.tabs {
	display: flex;
	margin-bottom: 20px;
	border-bottom: 2px solid #ddd;
}

.tab {
	padding: 10px 20px;
	cursor: pointer;
	border: none;
	background: none;
	color: #666;
	border-radius: 0;
	margin: 0;
}

.tab.active {
	color: #4facfe;
	border-bottom: 2px solid #4facfe;
	background: rgba(79, 172, 254, 0.1);
}

.tab-content {
	display: none;
}

.tab-content.active {
	display: block;
}

.challenge {
	background: linear-gradient(135deg, #ff9a9e 0%, #fecfef 100%);
	border-radius: 15px;
	padding: 20px;
	margin: 20px 0;
	color: #333;
}

.challenge h4 {
	margin-bottom: 10px;
	color: #d63384;
}