/* ========================================
   SHARED VARIABLES
   ======================================== */

:root {
    --primary-dark: #003366;
    --primary-medium: #336699;
    --accent-green: #4CAF50;
    --accent-yellow: #FFEB3B;
    --white: #FFFFFF;
    --text-primary: #1a202c;
    --text-secondary: #718096;
    --border-color: #e2e8f0;
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
    --radius-md: 12px;
    --radius-lg: 16px;
    --transition: all 0.3s ease;
}

/* ========================================
   BASE LAYOUT
   ======================================== */

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

.lesson-container {
    margin: 2rem auto;
    padding: 0 1rem;
    background: #f8fafc;
    min-height: 100vh;
}

.lesson-card {
    background: white;
    border-radius: var(--radius-lg);
    box-shadow: 0 4px 20px rgba(0, 51, 102, 0.06);
    border: 1px solid rgba(51, 102, 153, 0.08);
    overflow: hidden;
    margin-bottom: 2rem;
}

/* ========================================
   AUTHOR LINK HOVER
   ======================================== */

.author-link {
    text-decoration: none;
    color: inherit;
    position: relative;
    display: inline-block;
    transition: color 0.3s ease;
}

.author-link::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: -2px;
    left: 0;
    background-color: var(--accent-green);
    transition: width 0.3s ease;
}

.author-link:hover {
    text-decoration: none;
}

.author-link:hover::after {
    width: 100%;
}

.author-link h4 {
    margin: 0;
    transition: var(--transition);
}

/* ========================================
   RESPONSIVE
   ======================================== */

@media (max-width: 768px) {
    .lesson-container {
        margin: 1rem auto;
        padding: 0 0.5rem;
    }
}