:root {
    /* Light Mode Variables */
    --primary-color: #0f5132;
    --secondary-color: #d1e7dd;
    --accent-color: #ffd700;
    --bg-body: #f8f9fa;
    --text-body: #333;
    --text-muted: #6c757d;
    --card-bg: #ffffff;
    --nav-bg: #0f5132;
    --border-color: #dee2e6;
    --input-bg: #ffffff;
    --shadow-color: rgba(0,0,0,0.1);
}

[data-theme="dark"] {
    /* Dark Mode Variables - High Contrast */
    --primary-color: #4ade80; /* Brighter Green for text on dark bg */
    --secondary-color: #2f3e35;
    --accent-color: #facc15;
    --bg-body: #121212;
    --text-body: #f8f9fa;
    --text-muted: #ced4da;
    --card-bg: #1e1e1e;
    --nav-bg: #064e3b;
    --border-color: #374151;
    --input-bg: #2d2d2d;
    --shadow-color: rgba(0,0,0,0.5);
}

body {
    font-family: 'Poppins', sans-serif;
    background-color: var(--bg-body);
    color: var(--text-body);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    padding-top: 70px;
    overflow-x: hidden;
    transition: background-color 0.3s ease, color 0.3s ease;
}

h1, h2, h3, h4, h5 {
    color: var(--primary-color);
}

.text-muted {
    color: var(--text-muted) !important;
}

.arabic-text {
    font-family: 'Amiri', serif;
    color: var(--primary-color);
    direction: rtl;
}

/* Responsive Typography */
@media (max-width: 576px) {
    h1.arabic-text.display-1 {
        font-size: 3rem; 
    }
    h2.arabic-text.display-6 {
        font-size: 2rem; 
    }
}

.tamil-text {
    font-family: 'Noto Sans Tamil', sans-serif;
}

/* Custom Modern Navbar */
.custom-nav {
    background-color: var(--nav-bg);
    padding: 0 1.5rem;
    height: 70px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 4px 20px var(--shadow-color);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    transition: background-color 0.3s ease;
}

.nav-brand {
    color: white;
    font-size: 1.2rem;
    font-weight: 700;
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 10px;
    letter-spacing: 0.5px;
    flex-shrink: 0;
}

.nav-brand:hover { color: var(--accent-color); }

/* Main Navigation Menu */
.nav-menu {
    display: flex;
    gap: 2rem;
    list-style: none;
    margin: 0;
    padding: 0;
    margin-left: auto;
    margin-right: 1.5rem;
}

.nav-item-link {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
    transition: all 0.3s ease;
    cursor: pointer;
    font-size: 0.95rem;
    white-space: nowrap;
}

.nav-item-link:hover {
    color: #fff;
    transform: translateY(-2px);
}

.nav-item-link.active {
    color: white;
    font-weight: 600;
}

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

.nav-item-link.active::after,
.nav-item-link:hover::after {
    width: 100%;
}

/* Mobile Actions & Toggle */
.mobile-actions {
    display: flex;
    align-items: center;
    gap: 10px;
}

.nav-icon-btn, .nav-toggle {
    background: none;
    border: none;
    color: white;
    font-size: 1.4rem;
    cursor: pointer;
    padding: 8px;
    transition: color 0.3s ease, transform 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.nav-icon-btn:hover, .nav-toggle:hover {
    color: var(--accent-color);
    transform: scale(1.1);
}

/* Modules Menu (Right Sidebar) */
.modules-menu {
    position: fixed;
    top: 70px;
    right: 0;
    width: 100%; 
    height: calc(100vh - 70px);
    background-color: var(--nav-bg);
    z-index: 1001;
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    transform: translateX(100%);
    transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1), background-color 0.3s ease;
    overflow-y: auto;
}

@media (min-width: 769px) {
    .modules-menu {
        width: 400px;
        border-left: 1px solid rgba(255,255,255,0.1);
        box-shadow: -5px 0 15px var(--shadow-color);
        background-color: #1a5c3d; /* Distinct green for sidebar on desktop */
    }
    [data-theme="dark"] .modules-menu {
        background-color: #0b3d26;
    }
    .nav-brand { font-size: 1.4rem; }
    .nav-toggle { display: none; }
}

.modules-menu.open {
    transform: translateX(0);
}

.module-header {
    color: var(--accent-color);
    font-size: 1.2rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    border-bottom: 1px solid rgba(255,255,255,0.1);
    padding-bottom: 10px;
    margin-bottom: 10px;
}

.module-link {
    display: flex;
    align-items: center;
    padding: 15px;
    background: rgba(255,255,255,0.05);
    border-radius: 10px;
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.2s;
    border: 1px solid transparent;
}

.module-link:hover {
    background: rgba(255,255,255,0.15);
    border-color: var(--accent-color);
    color: white;
    transform: translateX(-5px);
}

.module-link i {
    width: 30px;
    font-size: 1.2rem;
    color: var(--accent-color);
}

/* Mobile Responsive Navigation Styles */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 70px;
        right: 0;
        width: 100%;
        height: calc(100vh - 70px);
        background-color: var(--nav-bg);
        margin-left: 0;
        margin-right: 0;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 2.5rem;
        transform: translateX(100%);
        transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1);
        z-index: 1000;
    }

    .nav-menu.open {
        transform: translateX(0);
    }

    .nav-item-link {
        display: inline-block;
        padding: 15px;
        font-size: 1.5rem;
        border: none;
        width: auto;
    }

    .nav-item-link:hover {
        transform: scale(1.1);
        color: var(--accent-color);
    }
    
    .nav-item-link::after {
        display: none;
    }
    
    .nav-item-link.active {
        color: var(--accent-color);
        font-weight: 700;
        transform: scale(1.1);
    }
}

/* Card Styles */
.name-card {
    border: none;
    border-radius: 15px;
    background: var(--card-bg);
    box-shadow: 0 5px 15px var(--shadow-color);
    transition: transform 0.3s ease, box-shadow 0.3s ease, background-color 0.3s ease;
    height: 100%;
    overflow: hidden;
    position: relative;
}

.name-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px var(--shadow-color);
}

.card-number {
    position: absolute;
    top: 10px;
    left: 10px;
    background-color: var(--secondary-color);
    color: var(--primary-color);
    width: 30px;
    height: 30px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    font-size: 0.9rem;
}

/* Audio Button Style */
.btn-audio {
    background-color: var(--secondary-color);
    color: var(--primary-color);
    border: none;
    border-radius: 50%;
    width: 35px;
    height: 35px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-audio:hover {
    transform: scale(1.1);
    background-color: var(--primary-color);
    color: white;
}

/* Dark Mode Specific Overrides for Contrast */
[data-theme="dark"] .card-number,
[data-theme="dark"] .btn-audio {
    background-color: rgba(255, 255, 255, 0.1);
    color: var(--primary-color);
}

[data-theme="dark"] .btn-audio:hover {
    background-color: var(--primary-color);
    color: #000;
}

/* Learned Checkbox Style */
.learned-check {
    position: absolute;
    top: 10px;
    right: 10px;
    cursor: pointer;
}

.learned-check i {
    font-size: 1.2rem;
    color: #ccc;
    transition: color 0.3s;
}

.learned-check.active i {
    color: #198754;
}

/* Flashcard Flip Animation */
.flashcard-container {
    perspective: 1000px;
    width: 100%;
    max-width: 500px;
    height: 400px;
    margin: 0 auto;
    cursor: pointer;
}

@media (max-width: 576px) {
    .flashcard-container {
        height: 350px;
    }
}

.flashcard-inner {
    position: relative;
    width: 100%;
    height: 100%;
    text-align: center;
    transition: transform 0.6s;
    transform-style: preserve-3d;
    box-shadow: 0 4px 8px 0 var(--shadow-color);
    border-radius: 20px;
}

.flashcard-container.flipped .flashcard-inner {
    transform: rotateY(180deg);
}

.flashcard-front, .flashcard-back {
    position: absolute;
    width: 100%;
    height: 100%;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    border-radius: 20px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 20px;
    background-color: var(--card-bg);
    border: 2px solid var(--secondary-color);
}

.flashcard-front {
    background: linear-gradient(135deg, var(--card-bg) 0%, var(--bg-body) 100%);
}

.flashcard-back {
    background-color: var(--primary-color);
    color: white;
    transform: rotateY(180deg);
}

/* Dark mode specific: Text on bright green background must be black */
[data-theme="dark"] .flashcard-back {
    color: #000;
}

.flashcard-back h2, .flashcard-back p, .flashcard-back .tamil-text {
    color: inherit;
}

/* Quiz Styles */
.option-btn {
    text-align: left;
    transition: all 0.2s;
    border: 1px solid var(--border-color);
    white-space: normal;
    background-color: var(--card-bg);
    color: var(--text-body);
}

.option-btn:hover {
    background-color: var(--secondary-color);
    color: var(--primary-color);
}

.option-btn.correct {
    background-color: #d1e7dd;
    border-color: #0f5132;
    color: #0f5132;
}

.option-btn.wrong {
    background-color: #f8d7da;
    border-color: #842029;
    color: #842029;
}

/* Custom Search Input Styles */
.search-group {
    border-radius: 50px;
    background-color: var(--input-bg);
    border: 1px solid var(--border-color);
    transition: all 0.3s ease;
    overflow: hidden;
    box-shadow: 0 4px 15px var(--shadow-color);
}

.search-group:hover, .search-group:focus-within {
    border-color: var(--accent-color);
    box-shadow: 0 0 0 2px var(--accent-color);
}

.search-group .input-group-text {
    background-color: transparent;
    border: none;
    color: var(--text-muted);
}

.search-group #searchInput {
    border: none;
    box-shadow: none !important;
    background: transparent;
    color: var(--text-body);
}

/* Specific fix for Placeholder Contrast */
.search-group #searchInput::placeholder {
    color: var(--text-muted);
    opacity: 0.8;
}

[data-theme="dark"] .search-group #searchInput::placeholder {
    color: #b0b0b0; /* Much lighter gray for dark mode visibility */
    opacity: 1;
}

/* Quote Cards */
.quote-card {
    background: var(--card-bg);
    border-left: 5px solid var(--primary-color);
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: 0 2px 10px var(--shadow-color);
    border-radius: 5px;
}

.view-section {
    display: none;
    padding: 30px 0;
}

.view-section.active {
    display: block;
    animation: fadeIn 0.5s;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

footer {
    margin-top: auto;
    background-color: #343a40;
    color: white;
    padding: 20px 0;
    text-align: center;
}