:root {
    /* Color Palette */
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --secondary-gradient: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --success-gradient: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --accent-gradient: linear-gradient(135deg, #fa709a 0%, #fee140 100%);

    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --success-color: #00d4aa;
    --danger-color: #f5576c;
    --warning-color: #feca57;

    --text-dark: #2d3748;
    --text-muted: #718096;
    --text-light: #a0aec0;

    --bg-light: #f7fafc;
    --bg-white: #ffffff;
    --border-color: #e2e8f0;

    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.15);

    /* Transitions */
    --transition-fast: all 0.2s ease;
    --transition-normal: all 0.3s ease;
    --transition-slow: all 0.5s ease;
}

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

body {
    font-family: 'Inter', sans-serif;
    background: var(--bg-light);
    color: var(--text-dark);
    line-height: 1.6;
    overflow-x: hidden;
}

/* Bengali Font */
.bangla-text {
    font-family: 'Noto Sans Bengali', sans-serif;
}

/* Screen Management */
.screen {
    display: none;
    min-height: 100vh;
}

.screen.active {
    display: block;
}

/* ==================== PLAN SELECTION SCREEN ==================== */

/* Hero Section */
.hero-icon {
    width: 70px;
    height: 70px;
    margin: 0 auto;
    background: var(--primary-gradient);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    animation: float 3s ease-in-out infinite;
}

.checked-icon-color {
    color: var(--primary-color);
}

.hero-icon i {
    font-size: 2rem;
    color: white;
}

@keyframes float {

    0%,
    100% {
        transform: translateY(0);
    }

    50% {
        transform: translateY(-10px);
    }
}

/* Plan Cards */
.plan-card {
    position: relative;
    background: white;
    border-radius: 15px;
    padding: 1.25rem 1rem;
    text-align: center;
    cursor: pointer;
    transition: var(--transition-normal);
    border: 2px solid var(--border-color);
    overflow: hidden;
}

.plan-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--primary-gradient);
    transform: scaleX(0);
    transition: var(--transition-normal);
}

.plan-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.plan-card:hover::before {
    transform: scaleX(1);
}

.plan-badge {
    position: absolute;
    top: 12px;
    right: -30px;
    background: var(--success-gradient);
    color: white;
    padding: 4px 35px;
    font-size: 0.7rem;
    font-weight: 600;
    transform: rotate(45deg);
    box-shadow: var(--shadow-md);
}

.plan-badge.badge-intense {
    background: var(--secondary-gradient);
}

.plan-icon {
    width: 50px;
    height: 50px;
    margin: 0 auto 1rem;
    background: var(--primary-gradient);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-normal);
}

.plan-card:hover .plan-icon {
    transform: scale(1.1) rotate(5deg);
}

.plan-icon i {
    font-size: 1.5rem;
    color: white;
}

.plan-title {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.plan-stats {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1.25rem;
}

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

.stat-value {
    font-size: 1.5rem;
    font-weight: 700;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 0.25rem;
}

.stat-divider {
    width: 1px;
    height: 35px;
    background: var(--border-color);
}

.btn-select-plan {
    width: 100%;
    padding: 0.75rem 1.5rem;
    background: var(--primary-gradient);
    color: white;
    border: none;
    border-radius: 10px;
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    transition: var(--transition-normal);
    box-shadow: var(--shadow-md);
}

.btn-select-plan:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-lg);
}

.btn-select-plan:active {
    transform: scale(0.98);
}

.info-section {
    margin-top: 2rem;
    padding: 1rem;
    background: white;
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

/* ==================== LEARNING SCREEN ==================== */

/* Navbar */
.navbar {
    padding: 0.75rem 0;
}

.navbar-brand {
    font-size: 1.125rem;
    color: var(--text-dark);
    font-weight: 600;
}

.navbar-brand i {
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.plan-badge-header {
    background: var(--primary-gradient);
    padding: 0.4rem 0.875rem;
    border-radius: 15px;
    font-weight: 600;
    font-size: 0.8rem;
}

/* Progress Section */
.progress-section {
    background: white;
    padding: 1.25rem 0;
    box-shadow: var(--shadow-sm);
}

.stat-card {
    background: white;
    border-radius: 12px;
    padding: 1rem;
    display: flex;
    align-items: center;
    gap: 0.875rem;
    border: 2px solid var(--border-color);
    transition: var(--transition-normal);
}

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: var(--primary-color);
}

.stat-card-icon {
    width: 50px;
    height: 50px;
    background: var(--primary-gradient);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.stat-card-icon i {
    font-size: 1.5rem;
    color: white;
}

.stat-card-content {
    flex: 1;
}

.stat-card-value {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-dark);
    line-height: 1;
    margin-bottom: 0.25rem;
}

.stat-card-label {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 500;
}

/* Progress Bar */
.progress-bar-container {
    background: white;
    padding: 1rem;
    border-radius: 12px;
    border: 2px solid var(--border-color);
    position: relative;
}

.custom-progress {
    height: 28px;
    border-radius: 14px;
    background: var(--bg-light);
    overflow: hidden;
    position: relative;
}

.custom-progress .progress-bar {
    background: var(--primary-gradient);
    border-radius: 14px;
    transition: width 0.6s ease;
    height: 100%;
}

.progress-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-weight: 600;
    font-size: 0.75rem;
    color: var(--text-dark);
    z-index: 10;
    white-space: nowrap;
}

/* Motivational Message */
.motivational-message {
    padding: 0.75rem;
    background: linear-gradient(135deg, #fff5e6 0%, #ffe6f0 100%);
    border-radius: 10px;
    color: var(--text-dark);
    font-weight: 500;
    font-size: 0.9rem;
    animation: pulse 2s ease-in-out infinite;
}

.motivational-message i {
    color: var(--warning-color);
}

@keyframes pulse {

    0%,
    100% {
        transform: scale(1);
    }

    50% {
        transform: scale(1.02);
    }
}

/* Vocabulary Section */
.vocabulary-section {
    padding: 2rem 0;
}

.section-header {
    text-align: center;
}

.section-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.section-title i {
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-subtitle {
    color: var(--text-muted);
    font-size: 0.95rem;
}

/* Vocabulary Cards */
.vocab-card {
    background: white;
    border-radius: 10px;
    padding: 1rem 1.25rem;
    border: 2px solid var(--border-color);
    transition: var(--transition-normal);
    margin-bottom: 0.75rem;
    position: relative;
}

.vocab-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.vocab-number {
    position: absolute;
    top: 0.75rem;
    right: 0.75rem;
    min-width: 30px;
    height: 30px;
    background: var(--primary-gradient);
    color: white;
    border-radius: 50%;
    text-align: center;
    line-height: 30px;
    font-weight: 700;
    font-size: 0.75rem;
}

.vocab-header {
    margin-bottom: 0.75rem;
}

.vocab-word {
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--text-dark);
    display: inline;
}

.vocab-pronunciation {
    font-family: 'Noto Sans Bengali', sans-serif;
    font-size: 0.875rem;
    color: var(--text-muted);
    display: inline;
    margin-left: 0.5rem;
}

.vocab-meaning {
    font-family: 'Noto Sans Bengali', sans-serif;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 0.75rem;
}

.vocab-example {
    margin-bottom: 0.5rem;
}

.example-text {
    font-size: 0.9rem;
    color: var(--text-dark);
    font-style: italic;
    line-height: 1.5;
    margin-bottom: 0.4rem;
}

.example-translation {
    font-family: 'Noto Sans Bengali', sans-serif;
    font-size: 0.9rem;
    color: var(--text-muted);
    line-height: 1.5;
}

/* Navigation Section */
.navigation-section {
    margin-top: 2rem;
    padding: 1.25rem;
    background: white;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.navigation-section .btn {
    padding: 0.75rem;
    font-weight: 600;
    font-size: 0.9rem;
    border-radius: 10px;
    transition: var(--transition-normal);
}

.navigation-section .btn:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.navigation-section .btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

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

@media (max-width: 768px) {
    .hero-icon {
        width: 60px;
        height: 60px;
    }

    .hero-icon i {
        font-size: 1.75rem;
    }

    .plan-card {
        margin-bottom: 0.75rem;
        padding: 1rem;
    }

    .plan-title {
        font-size: 1rem;
    }

    .stat-value {
        font-size: 1.25rem;
    }

    .section-title {
        font-size: 1.25rem;
    }

    .vocab-card {
        padding: 0.875rem 1rem;
    }

    .vocab-word {
        font-size: 1rem;
    }

    .vocab-pronunciation {
        font-size: 0.8rem;
    }

    .example-text,
    .example-translation {
        font-size: 0.85rem;
    }

    .stat-card {
        padding: 0.875rem;
    }

    .stat-card-icon {
        width: 45px;
        height: 45px;
    }

    .stat-card-value {
        font-size: 1.5rem;
    }

    .navigation-section {
        padding: 1rem;
    }
}

@media (max-width: 576px) {
    .plan-stats {
        gap: 1rem;
    }

    .stat-value {
        font-size: 1.25rem;
    }

    .vocab-card {
        padding: 1rem;
    }

    .custom-progress {
        height: 24px;
    }

    .progress-text {
        font-size: 0.7rem;
    }

    .example-text,
    .example-translation {
        font-size: 0.8rem;
    }
}

/* ==================== ANIMATIONS ==================== */

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.vocab-card {
    animation: fadeIn 0.5s ease forwards;
}

.vocab-card:nth-child(1) {
    animation-delay: 0.1s;
}

.vocab-card:nth-child(2) {
    animation-delay: 0.2s;
}

.vocab-card:nth-child(3) {
    animation-delay: 0.3s;
}

.vocab-card:nth-child(4) {
    animation-delay: 0.4s;
}

.vocab-card:nth-child(5) {
    animation-delay: 0.5s;
}

.vocab-card:nth-child(6) {
    animation-delay: 0.6s;
}

/* ==================== UTILITY CLASSES ==================== */

.text-gradient {
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}