:root {
    --primary: #0056b3;
    --accent: #28a745;
    --bg: #f8f9fa;
    --card-bg: #ffffff;
    --text: #212529;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: system-ui, -apple-system, sans-serif;
}

body {
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    scroll-behavior: smooth;
}

h1
{
    font-size: 1.25rem;
    font-weight: 600;
}
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 10px;
}



.main-wrapper {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    margin-top: 10px;
}

.content-area {
    flex: 0 0 100%;
    max-width: 100%;
}

.sidebar {
    flex: 0 0 100%;
    max-width: 100%;
}

@media (min-width: 768px) {

    .content-area {
        flex: 0 0 calc(75% - 15px);
        max-width: calc(75% - 15px);
    }

    .sidebar {
        flex: 0 0 25%;
        max-width: 25%;
    }
}

.card-box {
    background: var(--card-bg);
    border: 1px solid #dee2e6;
    border-radius: 8px;
    padding: 15px;
    margin-bottom: 15px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

.hidden-box {
    display: none;
}

.box-heading {
    font-size: 1.1rem;
    color: var(--primary);
    margin-bottom: 12px;
    border-bottom: 2px solid var(--primary);
    padding-bottom: 5px;
}

.level-group {
    border: 1px solid #ced4da;
    border-radius: 6px;
    margin-bottom: 20px;
    background: #fff;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
    overflow: hidden;
}

.level-title {
    background-color: #e9ecef;
    color: #212529;
    font-size: 1.15rem;
    font-weight: 600;
    padding: 10px 15px;
    border-bottom: 1px solid #ced4da;
}

.level-content {
    padding: 15px;
}

.btn-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.custom-btn {
    background: #f0f4f8;
    border: 1px solid #cbd5e1;
    padding: 8px 14px;
    border-radius: 5px;
    cursor: pointer;
    color: #334155;
    font-size: 14px;
    font-weight: 600;
    transition: all 0.2s;
}

.custom-btn:hover,
.custom-btn.active {
    background: var(--primary);
    color: #fff;
    border-color: var(--primary);
}

.topics-container {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.topic-group {
    background: #fff;
    border: 1px solid #e2e8f0;
    border-radius: 6px;
    overflow: hidden;
}

.topic-heading {
    background: #f1f5f9;
    font-weight: 700;
    color: #0f172a;
    padding: 10px 15px;
    border-bottom: 1px solid #e2e8f0;
    font-size: 15px;
}

.topic-items {
    padding: 15px;
    line-height: 2.2;
    font-size: 14px;
}

.topic-item {
    display: inline-block;
    text-decoration: none;
    color: #1e293b;
    font-weight: 500;
    transition: color 0.2s;
}

.topic-item:hover {
    color: var(--primary);
    text-decoration: underline;
}

.topic-sep {
    color: #cbd5e1;
    margin: 0 10px;
    font-weight: bold;
    display: inline-block;
}

.error-msg {
    background: #f8d7da;
    color: #721c24;
    padding: 15px;
    border: 1px solid #f5c6cb;
    border-radius: 5px;
    font-weight: bold;
    font-size: 14px;
}

@keyframes blinkHighlight {

    0% {
        background-color: rgba(40,167,69,0.2);
        box-shadow: 0 0 12px rgba(40,167,69,0.4);
        transform: scale(0.99);
    }

    50% {
        background-color: rgba(40,167,69,0.05);
        transform: scale(1);
    }

    100% {
        background-color: var(--card-bg);
        box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    }
}

.flash-highlight {
    animation: blinkHighlight 1s ease-out;
}

/* 2. Navigation Bar Styles (Desktop) */
        .navbar {
            display: flex;
            justify-content: space-between;
            align-items: center;
            background-color: #ffffff;
            padding: 15px 40px;
            box-shadow: 0 2px 10px rgba(0,0,0,0.05);
            position: relative;
        }

        .logo {
            font-size: 24px;
            font-weight: bold;
            color: #2c3e50;
            text-decoration: none;
        }

        /* மறைக்கப்பட்ட Checkbox */
        .menu-toggle {
            display: none;
        }

        .nav-menu {
            display: flex;
            list-style: none;
            gap: 25px;
        }

        .nav-menu a {
            text-decoration: none;
            color: #555;
            font-size: 16px;
            font-weight: 500;
            transition: color 0.3s ease;
        }

        .nav-menu a:hover {
            color: #3498db;
        }

        /* Hamburger Icon (Hidden on Desktop) */
        .hamburger {
            display: none;
            cursor: pointer;
            flex-direction: column;
            justify-content: space-between;
            width: 25px;
            height: 20px;
        }

        .hamburger span {
            display: block;
            height: 3px;
            width: 100%;
            background-color: #333;
            border-radius: 2px;
            transition: all 0.3s ease;
        }

        /* 3. Main Content */
        .main-content {
            flex: 1;
            padding: 50px 20px;
            text-align: center;
        }

        /* 4. Footer */
        .footer {
            background-color: #2c3e50;
            color: #ffffff;
            text-align: center;
            padding: 20px;
            font-size: 14px;
        }

        /* 5. Mobile Responsiveness (Screens <= 768px) */
        @media (max-width: 768px) {
            .navbar {
                padding: 15px 20px;
            }

            /* Show Hamburger Icon */
            .hamburger {
                display: flex;
            }

            /* Hide Menu by default on mobile */
            .nav-menu {
                display: none;
                flex-direction: column;
                position: absolute;
                top: 100%;
                left: 0;
                width: 100%;
                background-color: #ffffff;
                box-shadow: 0 10px 15px rgba(0,0,0,0.05);
                padding: 20px 0;
                text-align: center;
                gap: 15px;
            }

            /* CSS MAGIC: Checkbox Tick ஆகும் போது மெனுவை காட்டு (No JS needed) */
            .menu-toggle:checked ~ .nav-menu {
                display: flex;
            }

            /* Hamburger Animation to 'X' mark (CSS only) */
            .menu-toggle:checked ~ .hamburger span:nth-child(1) {
                transform: translateY(8.5px) rotate(45deg);
            }
            .menu-toggle:checked ~ .hamburger span:nth-child(2) {
                opacity: 0;
            }
            .menu-toggle:checked ~ .hamburger span:nth-child(3) {
                transform: translateY(-8.5px) rotate(-45deg);
            }
        }
        
        
        /* Author Card Sidebar Styling */
.author-card {
  background-color: #ffffff;
  border: 1px solid #e5e7eb;
  border-radius: 12px;
  padding: 24px 20px;
  text-align: center;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
  width: 100%;
  box-sizing: border-box;
  margin-bottom: 20px;
}

.author-avatar {
  margin: 0 auto 12px auto;
  width: 90px;
  height: 90px;
}

.author-avatar img {
  width: 100%;
  height: 100%;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid #1e3a8a;
  display: block;
}

.author-name {
  font-size: 1.2rem;
  font-weight: 700;
  color: #0f172a; /* High Contrast Dark Slate */
  margin: 0 0 4px 0;
}

.author-role {
  font-size: 0.85rem;
  color: #1e3a8a; /* Dark Royal Blue */
  font-weight: 600;
  margin: 0 0 12px 0;
}

.author-bio {
  font-size: 0.875rem;
  color: #374151; /* WCAG 4.5:1+ Pass Text Color */
  line-height: 1.5;
  margin: 0 0 16px 0;
}

.author-stats {
  display: flex;
  justify-content: space-around;
  padding: 12px 0;
  border-top: 1px solid #f3f4f6;
  border-bottom: 1px solid #f3f4f6;
  margin-bottom: 16px;
}

.stat-item {
  display: flex;
  flex-direction: column;
}

.stat-num {
  font-size: 1.1rem;
  font-weight: 700;
  color: #0f172a;
}

.stat-label {
  font-size: 0.75rem;
  color: #4b5563;
}

.author-btn {
  display: block;
  width: 100%;
  padding: 10px 0;
  background-color: #0f172a; /* 15.5:1 Contrast Ratio with White Text */
  color: #ffffff !important;
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 600;
  border-radius: 8px;
  box-sizing: border-box;
  transition: background-color 0.2s ease;
}

.author-btn:hover {
  background-color: #1e3a8a;
}