:root {
    --primary: #4F46E5;
    --primary-hover: #4338CA;
    --bg-dark: #0F172A;
    --bg-card: rgba(30, 41, 59, 0.7);
    --text-main: #F8FAFC;
    --text-muted: #94A3B8;
    --accent: #10B981;
    --border: rgba(255, 255, 255, 0.1);
    --glass-blur: blur(12px);
}

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');
@import url('https://fonts.googleapis.com/css2?family=Fira+Code:wght@400;500&display=swap');

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

body {
    font-family: 'Inter', sans-serif;
    background: var(--bg-dark);
    color: var(--text-main);
    line-height: 1.6;
    background-image: 
        radial-gradient(at 0% 0%, rgba(79, 70, 229, 0.15) 0px, transparent 50%),
        radial-gradient(at 100% 100%, rgba(16, 185, 129, 0.15) 0px, transparent 50%);
    background-attachment: fixed;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

/* Header */
header {
    margin-bottom: 3rem;
    text-align: center;
    padding: 2rem 0;
    position: relative;
}

h1 {
    font-size: 3rem;
    font-weight: 700;
    background: linear-gradient(to right, #60A5FA, #34D399);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 0.5rem;
    letter-spacing: -1px;
}

header p {
    color: var(--text-muted);
    font-size: 1.1rem;
    max-width: 600px;
    margin: 0 auto;
}

/* Glassmorphism Cards */
.grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
}

.card {
    background: var(--bg-card);
    backdrop-filter: var(--glass-blur);
    -webkit-backdrop-filter: var(--glass-blur);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 1.5rem;
    transition: all 0.3s ease;
    text-decoration: none;
    color: var(--text-main);
    display: flex;
    flex-direction: column;
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(to right, #4F46E5, #10B981);
    opacity: 0;
    transition: opacity 0.3s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.2), 0 10px 10px -5px rgba(0, 0, 0, 0.1);
    border-color: rgba(255, 255, 255, 0.2);
}

.card:hover::before {
    opacity: 1;
}

.card-number {
    font-size: 0.875rem;
    color: var(--accent);
    font-weight: 600;
    letter-spacing: 1px;
    text-transform: uppercase;
    margin-bottom: 0.5rem;
}

.card-title {
    font-size: 1.25rem;
    font-weight: 600;
    line-height: 1.4;
}

.back-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-main);
    text-decoration: none;
    background: rgba(255,255,255,0.1);
    padding: 0.5rem 1rem;
    border-radius: 8px;
    font-size: 0.9rem;
    font-weight: 500;
    transition: background 0.2s;
    margin-bottom: 2rem;
}

.back-btn:hover {
    background: rgba(255,255,255,0.2);
}

/* Lesson Content Reader */
.lesson-container {
    max-width: 900px;
    margin: 0 auto;
    background: var(--bg-card);
    backdrop-filter: var(--glass-blur);
    border: 1px solid var(--border);
    border-radius: 24px;
    padding: 3rem;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
}

.lesson-header {
    border-bottom: 1px solid var(--border);
    padding-bottom: 2rem;
    margin-bottom: 2rem;
}

/* Markdown Rendering Styles */
.markdown-body {
    color: var(--text-main);
}

.markdown-body h1, .markdown-body h2, .markdown-body h3, .markdown-body h4 {
    margin-top: 2em;
    margin-bottom: 1em;
    font-weight: 600;
    color: #fff;
}

.markdown-body h1 { font-size: 2.25rem; background: linear-gradient(to right, #60A5FA, #a78bfa); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;}
.markdown-body h2 { font-size: 1.8rem; border-bottom: 1px solid var(--border); padding-bottom: 0.5em; }
.markdown-body h3 { font-size: 1.5rem; }

.markdown-body p {
    margin-bottom: 1.25em;
    color: #cbd5e1;
}

.markdown-body ul, .markdown-body ol {
    margin-bottom: 1.25em;
    padding-left: 2em;
    color: #cbd5e1;
}

.markdown-body li {
    margin-bottom: 0.5em;
}

.markdown-body strong {
    color: #fff;
    font-weight: 600;
}

.markdown-body blockquote {
    border-left: 4px solid var(--primary);
    padding-left: 1em;
    color: var(--text-muted);
    font-style: italic;
    margin: 1.5em 0;
    background: rgba(79, 70, 229, 0.05);
    padding: 1rem;
    border-radius: 0 8px 8px 0;
}

/* Cool Code Blocks */
.markdown-body pre {
    background: #0f111a !important;
    border: 1px solid rgba(255,255,255,0.05);
    border-radius: 12px;
    padding: 1.5rem;
    overflow-x: auto;
    margin: 1.5em 0;
    box-shadow: inset 0 2px 4px 0 rgba(0,0,0,0.2);
}

.markdown-body code {
    font-family: 'Fira Code', monospace;
    font-size: 0.9em;
}

/* Inline Code */
.markdown-body p code, .markdown-body li code {
    background: rgba(255, 255, 255, 0.1);
    padding: 0.2em 0.4em;
    border-radius: 4px;
    color: #a78bfa;
}

/* Tables */
.markdown-body table {
    width: 100%;
    border-collapse: collapse;
    margin: 2em 0;
    overflow: hidden;
    border-radius: 12px;
    border: 1px solid var(--border);
    background: rgba(0,0,0,0.2);
}

.markdown-body th {
    background: rgba(255,255,255,0.05);
    padding: 1rem;
    text-align: left;
    font-weight: 600;
    border-bottom: 1px solid var(--border);
    color: #fff;
}

.markdown-body td {
    padding: 1rem;
    border-bottom: 1px solid var(--border);
    color: #cbd5e1;
}

.markdown-body tr:last-child td {
    border-bottom: none;
}

.markdown-body details {
    background: rgba(255,255,255,0.03);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 1rem;
    margin-bottom: 1rem;
}
.markdown-body summary {
    cursor: pointer;
    font-weight: 600;
    color: var(--accent);
    outline: none;
}

@media (max-width: 768px) {
    .lesson-container {
        padding: 1.5rem;
        border-radius: 16px;
    }
    h1 {
        font-size: 2rem;
    }
}