/* =========================================
   STEM Learning Hub - Science Page Styles
   Interactive and engaging elements
   ========================================= */

/* =========================================
   Animations
   ========================================= */
@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes scaleIn {
    from {
        opacity: 0;
        transform: scale(0.9);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
        opacity: 1;
    }
    50% {
        transform: scale(1.1);
        opacity: 0.7;
    }
}

@keyframes shimmer {
    0% {
        background-position: -200% 0;
    }
    100% {
        background-position: 200% 0;
    }
}

@keyframes bounce {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-10px);
    }
}

@keyframes glow {
    0%, 100% {
        box-shadow: 0 0 5px var(--science-color);
    }
    50% {
        box-shadow: 0 0 20px var(--science-color), 0 0 30px var(--science-color);
    }
}

/* =========================================
   Progress Tracker
   ========================================= */
.progress-tracker {
    margin-top: var(--spacing-xl);
    padding: var(--spacing-lg);
    background: var(--bg-primary);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
}

.tracker-stats {
    display: flex;
    justify-content: center;
    gap: var(--spacing-2xl);
    flex-wrap: wrap;
}

.tracker-stats .stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
}

.tracker-stats .stat-icon {
    font-size: 1.5rem;
}

.tracker-stats .stat-value {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--science-color);
}

.tracker-stats .stat-label {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
}

/* =========================================
   Enhanced Quiz System
   ========================================= */
.quiz-container {
    width: 100%;
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-xl);
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.quiz-header h3 {
    margin: 0;
    color: white;
}

.quiz-progress {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.quiz-score {
    font-weight: 600;
    color: rgba(255, 255, 255, 0.9);
}

.quiz-progress-bar {
    width: 150px;
    height: 8px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.quiz-progress-fill {
    height: 100%;
    background: white;
    border-radius: var(--radius-full);
    transition: width 0.3s ease;
    width: 0%;
}

.quiz-question-card {
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.question-number {
    font-size: var(--font-size-sm);
    color: rgba(255, 255, 255, 0.7);
    margin-bottom: var(--spacing-sm);
}

.question-text {
    font-size: var(--font-size-lg);
    color: white;
    margin-bottom: var(--spacing-lg);
}

.quiz-option {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    background: rgba(255, 255, 255, 0.1);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    margin-bottom: var(--spacing-sm);
}

.quiz-option:hover:not(.disabled) {
    background: rgba(255, 255, 255, 0.2);
    transform: translateX(5px);
}

.quiz-option input {
    display: none;
}

.option-marker {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 50%;
    font-weight: 600;
    color: white;
    transition: all var(--transition-fast);
}

.quiz-option:has(input:checked) .option-marker {
    background: white;
    color: var(--primary-color);
}

.option-text {
    flex: 1;
    color: white;
}

.option-indicator {
    width: 24px;
    height: 24px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    transition: all var(--transition-fast);
}

.quiz-option:has(input:checked) .option-indicator {
    border-color: white;
    background: white;
}

.quiz-option.disabled {
    cursor: not-allowed;
    opacity: 0.8;
}

.quiz-option.correct {
    background: rgba(16, 185, 129, 0.3);
    border: 2px solid var(--science-color);
}

.quiz-option.correct .option-marker {
    background: var(--science-color);
}

.quiz-option.incorrect {
    background: rgba(239, 68, 68, 0.3);
    border: 2px solid var(--mathematics-color);
}

.quiz-option.incorrect .option-marker {
    background: var(--mathematics-color);
}

.question-feedback {
    margin-top: var(--spacing-lg);
    padding: var(--spacing-md);
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
}

.feedback-text {
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

.feedback-text.correct {
    color: #4ade80;
}

.feedback-text.incorrect {
    color: #fbbf24;
}

.explanation {
    color: rgba(255, 255, 255, 0.9);
    font-size: var(--font-size-sm);
}

.submit-answer {
    margin-top: var(--spacing-md);
}

/* Quiz Results */
.quiz-results {
    text-align: center;
    padding: var(--spacing-2xl);
}

.results-icon {
    font-size: 4rem;
    margin-bottom: var(--spacing-md);
    animation: bounce 1s ease infinite;
}

.results-content h4 {
    font-size: var(--font-size-2xl);
    color: white;
    margin-bottom: var(--spacing-md);
}

.results-score {
    font-size: var(--font-size-lg);
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: var(--spacing-xl);
}

.retry-quiz {
    background: white;
    color: var(--primary-color);
}

/* =========================================
   Force Calculator
   ========================================= */
.interactive-calculator {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    margin: var(--spacing-xl) 0;
    border: 2px solid var(--primary-color);
}

.interactive-calculator h4 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-sm);
    color: var(--primary-color);
}

.calculator-grid {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
    margin: var(--spacing-xl) 0;
    flex-wrap: wrap;
}

.calc-input-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
}

.calc-input-group label {
    font-weight: 500;
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
}

.calc-input-group input {
    width: 120px;
    padding: var(--spacing-md);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    text-align: center;
    font-size: var(--font-size-lg);
    font-weight: 600;
    transition: all var(--transition-fast);
}

.calc-input-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(67, 97, 238, 0.2);
}

.calc-input-group .input-icon {
    font-size: 1.5rem;
}

.calc-equals,
.calc-times {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--primary-color);
}

.calculator-buttons {
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.calculator-result {
    margin-top: var(--spacing-lg);
    padding: var(--spacing-lg);
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    text-align: center;
    border-left: 4px solid var(--science-color);
}

.calculator-result .result-text {
    font-size: var(--font-size-lg);
    margin: 0;
}

/* Force Visual Animation */
.calculator-visual {
    margin-top: var(--spacing-xl);
    padding: var(--spacing-lg);
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
}

.force-animation-container {
    display: flex;
    align-items: center;
    justify-content: flex-start;
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
    background: linear-gradient(90deg, var(--bg-tertiary) 0%, var(--bg-secondary) 100%);
    border-radius: var(--radius-md);
    min-height: 80px;
    overflow: hidden;
}

.box-object {
    font-size: 2.5rem;
    transition: transform 0.5s ease-out;
}

.force-arrow {
    font-size: 2rem;
    color: var(--primary-color);
    opacity: 0.5;
    transform-origin: left center;
    transition: all 0.3s ease;
}

.visual-label {
    text-align: center;
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    margin-top: var(--spacing-md);
}

/* =========================================
   Matter Simulator
   ========================================= */
.matter-simulator {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    margin: var(--spacing-xl) 0;
}

.matter-simulator h4 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-sm);
}

.simulator-container {
    display: flex;
    gap: var(--spacing-xl);
    margin: var(--spacing-xl) 0;
    flex-wrap: wrap;
    justify-content: center;
}

.particle-container {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
}

#particle-canvas {
    display: block;
}

.temperature-control {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    min-width: 200px;
}

.temperature-control label {
    font-weight: 500;
    color: var(--text-secondary);
}

.temperature-control input[type="range"] {
    width: 100%;
    height: 8px;
    border-radius: var(--radius-full);
    background: linear-gradient(90deg, #4d96ff, #ffd93d, #ff6b6b);
    -webkit-appearance: none;
    cursor: pointer;
}

.temperature-control input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 24px;
    height: 24px;
    background: white;
    border: 3px solid var(--primary-color);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: var(--shadow-md);
}

.temp-display {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

#temp-value {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--primary-color);
}

.state-badge {
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-full);
    font-size: var(--font-size-sm);
    font-weight: 600;
    text-transform: uppercase;
}

.state-badge.solid {
    background: #e0e0e0;
    color: #424242;
}

.state-badge.liquid {
    background: #cce7ff;
    color: #1565c0;
}

.state-badge.gas {
    background: #fff3e0;
    color: #e65100;
}

.temp-markers {
    display: flex;
    justify-content: space-between;
    font-size: var(--font-size-sm);
    color: var(--text-light);
}

.simulator-info {
    background: var(--bg-primary);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    border-left: 4px solid var(--science-color);
}

.simulator-info p {
    margin: 0;
}

/* =========================================
   Enhanced Periodic Table
   ========================================= */
.elements-showcase .elements-grid {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    justify-content: center;
    margin-bottom: var(--spacing-lg);
}

.element-card.interactive {
    cursor: pointer;
    transition: all var(--transition-base);
    position: relative;
}

.element-card.interactive:hover {
    transform: scale(1.15) rotate(-2deg);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    z-index: 10;
}

.element-card .click-hint {
    position: absolute;
    bottom: -20px;
    left: 50%;
    transform: translateX(-50%);
    font-size: 0.6rem;
    color: var(--text-light);
    opacity: 0;
    transition: opacity var(--transition-fast);
    white-space: nowrap;
}

.element-card:hover .click-hint {
    opacity: 1;
}

.element-detail-panel {
    background: var(--bg-primary);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-lg);
    position: relative;
}

.close-panel {
    position: absolute;
    top: var(--spacing-md);
    right: var(--spacing-md);
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: var(--bg-tertiary);
    border: none;
    font-size: var(--font-size-xl);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.close-panel:hover {
    background: var(--border-color);
}

.element-large {
    width: 120px;
    height: 140px;
    border-radius: var(--radius-xl);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: white;
    margin: 0 auto var(--spacing-lg);
}

.element-large .element-number {
    font-size: var(--font-size-sm);
    opacity: 0.8;
}

.element-large .element-symbol {
    font-size: 3rem;
    font-weight: 700;
}

.element-large .element-name {
    font-size: var(--font-size-base);
}

.element-facts h4 {
    margin-bottom: var(--spacing-md);
    text-align: center;
}

.element-facts ul {
    list-style: none;
}

.element-facts li {
    padding: var(--spacing-sm) 0;
    color: var(--text-secondary);
}

/* =========================================
   DNA Game
   ========================================= */
.dna-game {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    margin: var(--spacing-xl) 0;
}

.dna-game h4 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-sm);
}

.dna-game-container {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    margin: var(--spacing-xl) 0;
}

.dna-strand {
    display: flex;
    justify-content: center;
    gap: var(--spacing-sm);
}

.base-pair {
    display: flex;
    flex-direction: column;
    align-items: center;
}

#dna-strand-2 .base-pair {
    flex-direction: column-reverse;
}

.dna-strand .base {
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-xl);
    font-weight: 700;
    border-radius: var(--radius-md);
    background: var(--primary-color);
    color: white;
}

#dna-strand-1 .base[data-base="A"] { background: #ff6b6b; }
#dna-strand-1 .base[data-base="T"] { background: #4ecdc4; }
#dna-strand-1 .base[data-base="G"] { background: #ffe66d; color: #333; }
#dna-strand-1 .base[data-base="C"] { background: #95e1d3; color: #333; }

.dna-strand .base.empty {
    background: var(--bg-tertiary);
    color: var(--text-light);
    border: 2px dashed var(--border-color);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.dna-strand .base.empty:hover {
    border-color: var(--primary-color);
    background: var(--bg-primary);
}

.dna-strand .base.filled {
    cursor: pointer;
}

.dna-strand .base.correct {
    background: var(--science-color) !important;
    color: white !important;
    animation: pulse 0.5s ease;
}

.dna-strand .base.incorrect {
    background: var(--mathematics-color) !important;
    color: white !important;
}

.dna-strand .bond {
    font-size: var(--font-size-lg);
    color: var(--text-light);
    height: 20px;
    display: flex;
    align-items: center;
}

.base-palette {
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
    margin: var(--spacing-xl) 0;
}

.base-btn {
    width: 60px;
    height: 60px;
    border-radius: var(--radius-lg);
    font-size: var(--font-size-xl);
    font-weight: 700;
    background: var(--base-color);
    color: white;
    border: 3px solid transparent;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.base-btn[data-base="A"] { --base-color: #ff6b6b; }
.base-btn[data-base="T"] { --base-color: #4ecdc4; }
.base-btn[data-base="G"] { --base-color: #ffe66d; color: #333; }
.base-btn[data-base="C"] { --base-color: #95e1d3; color: #333; }

.base-btn:hover {
    transform: scale(1.1);
}

.base-btn.selected {
    border-color: var(--text-primary);
    box-shadow: 0 0 0 3px rgba(0, 0, 0, 0.2);
    transform: scale(1.1);
}

.game-controls {
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
}

.game-feedback {
    margin-top: var(--spacing-lg);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    text-align: center;
    font-weight: 500;
}

.game-feedback.success {
    background: rgba(16, 185, 129, 0.1);
    color: var(--science-color);
    border: 1px solid var(--science-color);
}

.game-feedback.partial {
    background: rgba(245, 158, 11, 0.1);
    color: var(--engineering-color);
    border: 1px solid var(--engineering-color);
}

.game-feedback.error {
    background: rgba(239, 68, 68, 0.1);
    color: var(--mathematics-color);
    border: 1px solid var(--mathematics-color);
}

.game-score {
    text-align: center;
    margin-top: var(--spacing-md);
    font-weight: 600;
    color: var(--primary-color);
}

/* =========================================
   Cell Explorer
   ========================================= */
.cell-explorer {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    margin: var(--spacing-xl) 0;
}

.cell-explorer h4 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-sm);
}

.cell-diagram {
    display: flex;
    justify-content: center;
    margin: var(--spacing-xl) 0;
}

.cell-membrane {
    position: relative;
    width: 350px;
    height: 250px;
    background: linear-gradient(135deg, #e8f5e9 0%, #c8e6c9 100%);
    border: 4px solid #81c784;
    border-radius: 50% 50% 50% 50% / 60% 60% 40% 40%;
    box-shadow: var(--shadow-lg);
}

.organelle-marker {
    position: absolute;
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-fast);
    transform: translate(-50%, -50%);
}

.marker-icon {
    font-size: 1.8rem;
    z-index: 2;
    position: relative;
}

.marker-pulse {
    position: absolute;
    width: 100%;
    height: 100%;
    border-radius: 50%;
    background: rgba(16, 185, 129, 0.3);
    animation: pulse 2s ease-in-out infinite;
}

.organelle-marker:hover {
    transform: translate(-50%, -50%) scale(1.2);
}

.organelle-marker.active .marker-pulse {
    animation: glow 1s ease-in-out infinite;
}

.organelle-marker.discovered .marker-pulse {
    background: rgba(67, 97, 238, 0.3);
}

.organelle-info-panel {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    min-height: 150px;
}

.organelle-info-panel .hint {
    text-align: center;
    color: var(--text-light);
    margin: 0;
}

.organelle-detail {
    animation: slideIn 0.3s ease-out;
}

.detail-header {
    display: flex;
    gap: var(--spacing-md);
    align-items: flex-start;
    margin-bottom: var(--spacing-md);
}

.detail-icon {
    font-size: 2.5rem;
}

.detail-header h5 {
    font-size: var(--font-size-lg);
    margin: 0 0 var(--spacing-xs);
}

.detail-description {
    color: var(--text-secondary);
    margin: 0;
}

.detail-facts {
    list-style: none;
    margin-top: var(--spacing-md);
}

.detail-facts li {
    padding: var(--spacing-xs) 0;
    color: var(--text-secondary);
}

.explorer-progress {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
    font-weight: 500;
}

.explorer-progress .progress-bar {
    flex: 1;
    height: 8px;
    background: var(--bg-tertiary);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.explorer-progress .progress-fill {
    height: 100%;
    background: var(--science-color);
    border-radius: var(--radius-full);
    transition: width 0.5s ease;
    width: 0%;
}

/* =========================================
   Virtual Lab
   ========================================= */
.virtual-lab {
    background: var(--bg-secondary);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    margin: var(--spacing-xl) 0;
}

.virtual-lab h3 {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-sm);
}

.experiment-selector {
    display: flex;
    gap: var(--spacing-sm);
    margin: var(--spacing-lg) 0;
    flex-wrap: wrap;
}

.experiment-btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-full);
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    font-weight: 500;
    transition: all var(--transition-fast);
}

.experiment-btn:hover {
    background: var(--border-color);
}

.experiment-btn.active {
    background: var(--science-color);
    color: white;
}

.experiment-area {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
}

.experiment {
    display: none;
}

.experiment.active {
    display: block;
    animation: fadeIn 0.3s ease;
}

#pendulum-canvas {
    display: block;
    margin: 0 auto;
    background: linear-gradient(180deg, #e3f2fd 0%, #bbdefb 100%);
    border-radius: var(--radius-lg);
}

.experiment-controls {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-lg);
    flex-wrap: wrap;
}

.experiment-controls label {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-weight: 500;
}

.experiment-controls input[type="range"] {
    width: 100px;
}

.experiment-data {
    text-align: center;
    margin-top: var(--spacing-lg);
    font-size: var(--font-size-lg);
}

.experiment-data span {
    font-weight: 600;
    color: var(--primary-color);
}

/* =========================================
   Flashcard System
   ========================================= */
.flashcard-section {
    margin-top: var(--spacing-3xl);
    padding-top: var(--spacing-2xl);
    border-top: 1px solid var(--border-color);
}

.flashcard-topics {
    display: flex;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xl);
    flex-wrap: wrap;
}

.fc-topic-btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-full);
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    font-weight: 500;
    transition: all var(--transition-fast);
}

.fc-topic-btn:hover {
    background: var(--border-color);
}

.fc-topic-btn.active {
    background: var(--primary-color);
    color: white;
}

.flashcard-container {
    max-width: 500px;
    margin: 0 auto;
}

.flashcard {
    width: 100%;
    height: 250px;
    perspective: 1000px;
    cursor: pointer;
    margin-bottom: var(--spacing-xl);
}

.flashcard-inner {
    position: relative;
    width: 100%;
    height: 100%;
    transition: transform 0.6s;
    transform-style: preserve-3d;
}

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

.flashcard-front,
.flashcard-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.flashcard-front {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
}

.flashcard-back {
    background: var(--bg-primary);
    border: 2px solid var(--primary-color);
    transform: rotateY(180deg);
}

.fc-category {
    position: absolute;
    top: var(--spacing-md);
    left: var(--spacing-md);
    background: rgba(255, 255, 255, 0.2);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-full);
    font-size: var(--font-size-sm);
}

.fc-question {
    font-size: var(--font-size-lg);
    font-weight: 600;
}

.fc-hint {
    position: absolute;
    bottom: var(--spacing-md);
    font-size: var(--font-size-sm);
    opacity: 0.7;
}

.fc-answer {
    font-size: var(--font-size-base);
    color: var(--text-primary);
    line-height: 1.6;
}

.flashcard-controls {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-lg);
}

.fc-nav-btn {
    background: var(--bg-tertiary);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    font-weight: 500;
    transition: all var(--transition-fast);
}

.fc-nav-btn:hover {
    background: var(--border-color);
}

.fc-counter {
    font-weight: 600;
    color: var(--text-secondary);
}

.flashcard-actions {
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
}

.flashcard-progress {
    text-align: center;
    margin-top: var(--spacing-lg);
    color: var(--text-secondary);
}

.flashcard-progress span {
    font-weight: 600;
    color: var(--science-color);
}

/* =========================================
   Toast Notifications
   ========================================= */
.toast {
    position: fixed;
    bottom: 20px;
    right: 20px;
    padding: var(--spacing-md) var(--spacing-xl);
    background: var(--text-primary);
    color: white;
    border-radius: var(--radius-lg);
    font-weight: 500;
    box-shadow: var(--shadow-lg);
    transform: translateY(100px);
    opacity: 0;
    transition: all var(--transition-base);
    z-index: 9999;
}

.toast.show {
    transform: translateY(0);
    opacity: 1;
}

.toast-success {
    background: var(--science-color);
}

.toast-warning {
    background: var(--engineering-color);
}

.toast-info {
    background: var(--primary-color);
}

/* =========================================
   Achievement Notifications
   ========================================= */
.achievement-notifications {
    position: fixed;
    top: 80px;
    right: 20px;
    z-index: 9999;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.achievement-notif {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    background: linear-gradient(135deg, #ffd700 0%, #ffaa00 100%);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    transform: translateX(400px);
    transition: transform var(--transition-base);
}

.achievement-notif.show {
    transform: translateX(0);
}

.achievement-icon {
    font-size: 2rem;
}

.achievement-content strong {
    display: block;
    font-size: var(--font-size-sm);
    color: rgba(0, 0, 0, 0.6);
}

.achievement-content p {
    margin: 0;
    font-weight: 600;
    color: #333;
}

/* =========================================
   Responsive Styles
   ========================================= */
@media (max-width: 768px) {
    .tracker-stats {
        gap: var(--spacing-lg);
    }
    
    .calculator-grid {
        flex-direction: column;
    }
    
    .calc-equals,
    .calc-times {
        display: none;
    }
    
    .simulator-container {
        flex-direction: column;
    }
    
    .particle-container {
        width: 100%;
    }
    
    #particle-canvas {
        width: 100%;
        height: auto;
    }
    
    .cell-membrane {
        width: 280px;
        height: 200px;
    }
    
    .organelle-marker {
        width: 40px;
        height: 40px;
    }
    
    .marker-icon {
        font-size: 1.4rem;
    }
    
    .dna-strand {
        gap: var(--spacing-xs);
    }
    
    .dna-strand .base {
        width: 40px;
        height: 40px;
        font-size: var(--font-size-base);
    }
    
    .base-btn {
        width: 50px;
        height: 50px;
    }
    
    .flashcard {
        height: 200px;
    }
    
    .toast {
        left: 20px;
        right: 20px;
    }
    
    .achievement-notifications {
        left: 20px;
    }
    
    .achievement-notif {
        transform: translateY(-200px);
    }
    
    .achievement-notif.show {
        transform: translateY(0);
    }
}

@media (max-width: 480px) {
    .tracker-stats .stat-value {
        font-size: var(--font-size-xl);
    }
    
    .quiz-header {
        flex-direction: column;
        text-align: center;
    }
    
    .quiz-progress-bar {
        width: 100%;
    }
    
    .cell-membrane {
        width: 240px;
        height: 170px;
    }
    
    .base-palette {
        gap: var(--spacing-sm);
    }
    
    .base-btn {
        width: 45px;
        height: 45px;
        font-size: var(--font-size-base);
    }
    
    .experiment-controls {
        flex-direction: column;
    }
    
    .fc-question {
        font-size: var(--font-size-base);
    }
}