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

:root {
    --primary-color: #00758f;
    --secondary-color: #00a3bf;
    --accent-color: #f29111;
    --text-color: #333;
    --bg-light: #f9fafb;
    --bg-white: #ffffff;
    --border-color: #e5e7eb;
    --code-bg: #ffffff;
    --code-text: #24292f;
    --code-border: #d0d7de;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-light);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header Styles */
header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 3rem 0;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

header p {
    font-size: 1.2rem;
    opacity: 0.9;
    margin-bottom: 1.5rem;
}

nav ul {
    display: flex;
    justify-content: center;
    list-style: none;
    gap: 2rem;
}

nav a {
    color: white;
    text-decoration: none;
    font-weight: 500;
}

nav a:hover {
    text-decoration: underline;
}

/* Main Content */
main {
    padding: 3rem 0;
}

.section {
    background: var(--bg-white);
    border-radius: 8px;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.section h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--border-color);
}

.section h3 {
    color: var(--secondary-color);
    margin-top: 2rem;
    margin-bottom: 1rem;
}

.section p {
    margin-bottom: 1rem;
}

/* Feature Grid */
.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-top: 1.5rem;
}

.feature-card {
    background: var(--bg-light);
    padding: 1.5rem;
    border-radius: 8px;
    border-left: 4px solid var(--secondary-color);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.feature-card:hover {
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.feature-card h3 {
    margin-top: 0;
    color: var(--primary-color);
}

/* Tabs */
.tabs {
    margin-top: 1.5rem;
}

.tab-buttons {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.tab-button {
    padding: 0.75rem 1.5rem;
    background: var(--bg-light);
    border: 2px solid var(--border-color);
    border-radius: 4px;
    font-size: 1rem;
    font-weight: 500;
    color: var(--primary-color);
}

.tab-button:hover {
    background: var(--border-color);
}

.tab-content {
    display: block;
    background: var(--code-bg);
    border: 1px solid var(--code-border);
    padding: 0;
    border-radius: 4px;
    overflow-x: auto;
    margin-bottom: 1.5rem;
}

.tab-content pre {
    padding: 1rem;
    margin: 0;
    white-space: pre-wrap;
    word-wrap: break-word;
    background: transparent;
    color: var(--code-text);
    font-family: 'Courier New', Courier, monospace;
    font-size: 0.95rem;
    line-height: 1.6;
    border-radius: 4px;
}

.code-block {
    background: var(--code-bg);
    border: 1px solid var(--code-border);
    padding: 1.5rem;
    border-radius: 4px;
    margin: 1rem 0;
    overflow-x: auto;
}

.code-block pre {
    color: var(--code-text);
    font-family: 'Courier New', Courier, monospace;
    line-height: 1.5;
    margin: 0;
    overflow-x: auto;
}

.code-block code {
    font-size: 0.95rem;
    color: var(--code-text);
}

/* Practice Projects */
.practice-project {
    background: var(--bg-light);
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 1.5rem;
}

.practice-project h3 {
    margin-top: 0;
    color: var(--primary-color);
}

details {
    margin-top: 1rem;
}

details summary {
    cursor: pointer;
    color: var(--secondary-color);
    font-weight: 500;
    padding: 0.5rem;
    background: var(--bg-white);
    border-radius: 4px;
    transition: background 0.3s;
}

details summary:hover {
    background: var(--border-color);
}

details[open] summary {
    border-bottom-left-radius: 0;
    border-bottom-right-radius: 0;
}

/* Tips List */
.tips-list {
    display: grid;
    gap: 1.5rem;
}

.tip-item {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.tip-item h3 {
    margin-top: 0;
    margin-bottom: 0.5rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }

    header p {
        font-size: 1rem;
    }

    nav ul {
        flex-wrap: wrap;
        gap: 1rem;
    }

    .section {
        padding: 1.5rem;
    }

    .feature-grid {
        grid-template-columns: 1fr;
    }

    .tab-buttons {
        flex-wrap: wrap;
    }
}

/* Smooth Scrolling */
html {
    scroll-behavior: smooth;
}

/* Code Styles */
code {
    font-family: 'Courier New', Courier, monospace;
    background: #f6f8fa;
    padding: 2px 4px;
    border-radius: 3px;
    font-size: 0.9em;
}

pre code {
    background: transparent;
    padding: 0;
    color: inherit;
}

/* GitHub Light+ SQL Syntax Highlighting */
.code-block .kwd, .tab-content .kwd {
    color: #cf222e;
    font-weight: 600;
}

.code-block .str, .tab-content .str {
    color: #0a3069;
}

.code-block .com, .tab-content .com {
    color: #6e7781;
    font-style: italic;
}

.code-block .num, .tab-content .num {
    color: #0550ae;
}

.code-block .func, .tab-content .func {
    color: #8250df;
}

.code-block .type, .tab-content .type {
    color: #953800;
}

/* GitHub Light+ Shell Syntax Highlighting */
.code-block code.sh .cmd, .tab-content code.sh .cmd {
    color: #cf222e;
    font-weight: 600;
}

.code-block code.sh .str, .tab-content code.sh .str {
    color: #0a3069;
}

.code-block code.sh .com, .tab-content code.sh .com {
    color: #6e7781;
    font-style: italic;
}

.code-block code.sh .var, .tab-content code.sh .var {
    color: #953800;
}

.code-block code.sh .path, .tab-content code.sh .path {
    color: #0550ae;
}

.code-block code.sh .num, .tab-content code.sh .num {
    color: #0550ae;
}