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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #e0f2fe 0%, #bae6fd 50%, #7dd3fc 100%);
    color: #333;
    line-height: 1.6;
    min-height: 100vh;
    position: relative;
    overflow-x: hidden;
}

body::before {
    content: '';
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 1200 120'%3E%3Cpath d='M0,96L48,112C96,128,192,160,288,160C384,160,480,128,576,112C672,96,768,96,864,96C960,96,1056,96,1152,85.3C1248,75,1344,53,1392,42.7L1440,32L1440,120L1392,120C1344,120,1248,120,1152,120C1056,120,960,120,864,120C768,120,672,120,576,120C480,120,384,120,288,120C192,120,96,120,48,120L0,120Z' fill='%23ffffff20'/%3E%3C/svg%3E") bottom center/cover no-repeat;
    z-index: -3;
    animation: wave 6s ease-in-out infinite;
}

body::after {
    content: '';
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 1200 120'%3E%3Cpath d='M0,64L48,80C96,96,192,128,288,128C384,128,480,96,576,80C672,64,768,64,864,64C960,64,1056,64,1152,53.3C1248,43,1344,21,1392,10.7L1440,0L1440,120L1392,120C1344,120,1248,120,1152,120C1056,120,960,120,864,120C768,120,672,120,576,120C480,120,384,120,288,120C192,120,96,120,48,120L0,120Z' fill='%23ffffff30'/%3E%3C/svg%3E") bottom center/cover no-repeat;
    z-index: -2;
    animation: wave 8s ease-in-out infinite reverse;
}

@keyframes wave {
    0%, 100% {
        transform: translateX(0) translateY(0);
    }
    25% {
        transform: translateX(-25px) translateY(-10px);
    }
    50% {
        transform: translateX(0) translateY(-20px);
    }
    75% {
        transform: translateX(25px) translateY(-10px);
    }
}

.main-header {
    background: linear-gradient(135deg, #0c4a6e, #0369a1, #0284c7);
    color: white;
    padding: 2rem 0;
    text-align: center;
    box-shadow: 0 4px 12px rgba(12, 74, 110, 0.3);
    position: relative;
    z-index: 1;
}

.header-content h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.header-content p {
    font-size: 1.2rem;
    opacity: 0.9;
}

.teacher-menu {
    position: absolute;
    top: 1rem;
    right: 2rem;
}

.teacher-link {
    background: rgba(255, 255, 255, 0.1);
    border: 2px solid rgba(255, 255, 255, 0.3);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.3s ease;
    font-size: 1rem;
    display: inline-block;
}

.teacher-link:hover {
    background: rgba(255, 255, 255, 0.2);
    border-color: rgba(255, 255, 255, 0.6);
    transform: translateY(-2px);
    color: white;
}


.main-content {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 1rem;
}

.unit-container {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 12px;
    box-shadow: 0 8px 20px rgba(12, 74, 110, 0.15);
    overflow: hidden;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.3);
}

.unit-header {
    background: linear-gradient(135deg, #0f172a, #1e293b);
    color: white;
    padding: 1.5rem;
    text-align: center;
}

.unit-header h2 {
    font-size: 1.8rem;
    margin-bottom: 1rem;
}

.progress-bar {
    background: rgba(255, 255, 255, 0.2);
    height: 8px;
    border-radius: 4px;
    margin-bottom: 0.5rem;
    overflow: hidden;
}

.progress-fill {
    background: linear-gradient(90deg, #10b981, #34d399);
    height: 100%;
    width: 0%;
    transition: width 0.3s ease;
}

.progress-text {
    font-size: 0.9rem;
    opacity: 0.9;
}

.standard-card {
    padding: 2rem;
}

.clickable-card {
    cursor: pointer;
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.clickable-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 16px rgba(30, 64, 175, 0.15);
    border-color: #2563eb;
}

.start-button-section {
    text-align: center;
    padding: 2rem 0;
    border-top: 1px solid #e2e8f0;
    margin-top: 1.5rem;
}

.secure-mode-option {
    background: #f8fafc;
    border: 1px solid #e2e8f0;
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    text-align: left;
}

.secure-mode-option label {
    display: flex;
    align-items: center;
    font-weight: 600;
    color: #374151;
    cursor: pointer;
    font-size: 1rem;
}

.secure-mode-option input[type="checkbox"] {
    margin-right: 0.8rem;
    transform: scale(1.2);
}

.secure-mode-description {
    margin-top: 0.8rem;
    font-size: 0.9rem;
    color: #6b7280;
    line-height: 1.5;
    margin-bottom: 0;
}

.start-btn {
    background: linear-gradient(135deg, #1e40af, #2563eb);
    color: white;
    border: none;
    padding: 1rem 2rem;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    box-shadow: 0 4px 6px rgba(30, 64, 175, 0.2);
}

.start-btn:hover {
    background: linear-gradient(135deg, #1d4ed8, #3b82f6);
    transform: translateY(-2px);
    box-shadow: 0 6px 12px rgba(30, 64, 175, 0.3);
}

.question-container {
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    padding: 2rem;
    margin-top: 2rem;
}

.background-info {
    margin-bottom: 2rem;
    padding: 1.5rem;
    background: linear-gradient(135deg, #f8fafc, #f1f5f9);
    border-radius: 12px;
    border: 1px solid #e2e8f0;
}

.background-info h3 {
    color: #1e40af;
    margin-bottom: 1.5rem;
    font-size: 1.4rem;
    font-weight: 700;
}

.info-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 2rem;
    align-items: start;
}

.info-text p {
    font-size: 1rem;
    line-height: 1.7;
    margin-bottom: 1rem;
    color: #374151;
}

.info-image {
    text-align: center;
}

.info-image img {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    margin-bottom: 0.5rem;
}

.image-caption {
    font-size: 0.9rem;
    color: #6b7280;
    font-style: italic;
    margin: 0;
}

.standard-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 1rem;
}

.standard-header h3 {
    font-size: 1.5rem;
    color: #1e40af;
    font-weight: 700;
}

.standard-badge {
    background: linear-gradient(135deg, #1e40af, #2563eb);
    color: white;
    padding: 0.4rem 0.8rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
}

.standard-description {
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
    padding: 1rem;
    background: #f8fafc;
    border-left: 4px solid #2563eb;
    border-radius: 4px;
}

.dci-section {
    background: #f1f5f9;
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 2rem;
}

.dci-section h4 {
    color: #1e40af;
    margin-bottom: 0.8rem;
    font-size: 1.2rem;
}

.dci-text {
    font-size: 1rem;
    line-height: 1.7;
}

.question-section {
    border-top: 2px solid #e2e8f0;
    padding-top: 2rem;
}

.question-section h4 {
    color: #1e40af;
    margin-bottom: 1rem;
    font-size: 1.3rem;
}

.question-text {
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
    padding: 1rem;
    background: #fefefe;
    border: 1px solid #e2e8f0;
    border-radius: 8px;
    line-height: 1.7;
}

.answer-options {
    display: flex;
    flex-direction: column;
    gap: 0.8rem;
    margin-bottom: 1.5rem;
}

.answer-btn {
    background: white;
    border: 2px solid #e2e8f0;
    padding: 1rem 1.2rem;
    border-radius: 8px;
    text-align: left;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.2s ease;
    color: #374151;
}

.answer-btn:hover {
    border-color: #2563eb;
    background: #f8fafc;
    transform: translateY(-1px);
}

.answer-btn.selected:not(.selected-correct):not(.selected-incorrect) {
    background: #dbeafe !important;
    border-color: #2563eb !important;
    color: #1e40af !important;
}

.answer-btn.selected-correct {
    background: #dcfce7 !important;
    border-color: #16a34a !important;
    color: #166534 !important;
    opacity: 1 !important;
}

.answer-btn.selected-incorrect {
    background: #fef2f2 !important;
    border-color: #dc2626 !important;
    color: #991b1b !important;
    opacity: 1 !important;
}

.answer-btn:disabled {
    cursor: not-allowed;
    opacity: 0.7;
}

.feedback-section {
    background: #f8fafc;
    padding: 1.5rem;
    border-radius: 8px;
    margin-top: 1rem;
}

.feedback-content {
    margin-bottom: 1rem;
}

.feedback-correct {
    color: #166534;
    background: #dcfce7;
    padding: 1rem;
    border-radius: 6px;
    border-left: 4px solid #16a34a;
}

.feedback-incorrect {
    color: #991b1b;
    background: #fef2f2;
    padding: 1rem;
    border-radius: 6px;
    border-left: 4px solid #dc2626;
}

.next-btn {
    background: linear-gradient(135deg, #1e40af, #2563eb);
    color: white;
    border: none;
    padding: 0.8rem 1.5rem;
    border-radius: 6px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
}

.next-btn:hover {
    background: linear-gradient(135deg, #1d4ed8, #3b82f6);
    transform: translateY(-1px);
}

.next-btn:disabled {
    background: #9ca3af;
    cursor: not-allowed;
    transform: none;
}

.scroll-indicator {
    position: fixed;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
    background: linear-gradient(135deg, #1e40af, #2563eb);
    color: white;
    padding: 12px 8px;
    border-radius: 25px;
    box-shadow: 0 4px 12px rgba(30, 64, 175, 0.3);
    animation: bounce 2s infinite;
    z-index: 1000;
    cursor: pointer;
    transition: all 0.3s ease;
}

.scroll-indicator:hover {
    background: linear-gradient(135deg, #1d4ed8, #3b82f6);
    transform: translateY(-50%) scale(1.1);
}

.scroll-indicator .arrow {
    display: block;
    width: 12px;
    height: 12px;
    border-right: 2px solid white;
    border-bottom: 2px solid white;
    transform: rotate(45deg);
    margin: 4px auto;
}

.scroll-indicator .text {
    font-size: 0.8rem;
    font-weight: 600;
    margin-top: 8px;
    text-align: center;
    line-height: 1.2;
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
        transform: translateY(-50%);
    }
    40% {
        transform: translateY(-60%);
    }
    60% {
        transform: translateY(-55%);
    }
}

.delay-timer {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 0.9rem;
    color: #6b7280;
    margin-left: 10px;
}

.delay-timer .timer-icon {
    width: 16px;
    height: 16px;
    border: 2px solid #6b7280;
    border-top: 2px solid #2563eb;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.completion-message {
    text-align: center;
    padding: 3rem 2rem;
    background: linear-gradient(135deg, #f0f9ff, #e0f2fe);
    border-radius: 12px;
    border: 2px solid #0ea5e9;
}

.completion-message h3 {
    color: #0c4a6e;
    font-size: 2rem;
    margin-bottom: 1.5rem;
}

.completion-content {
    max-width: 600px;
    margin: 0 auto;
}

.completion-content ul {
    text-align: left;
    margin: 1.5rem 0;
    padding-left: 1rem;
}

.completion-content li {
    margin-bottom: 0.5rem;
    color: #0c4a6e;
}

.completion-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-top: 2rem;
}

.restart-btn, .next-unit-btn {
    background: linear-gradient(135deg, #1e40af, #2563eb);
    color: white;
    border: none;
    padding: 1rem 1.5rem;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
}

.restart-btn:hover, .next-unit-btn:hover {
    background: linear-gradient(135deg, #1d4ed8, #3b82f6);
    transform: translateY(-2px);
}

.failure-screen {
    text-align: center;
    padding: 3rem 2rem;
    background: linear-gradient(135deg, #fef2f2, #fee2e2);
    border-radius: 12px;
    border: 2px solid #dc2626;
    max-width: 800px;
    margin: 0 auto;
}

.failure-screen h2 {
    color: #dc2626;
    font-size: 2.5rem;
    margin-bottom: 1.5rem;
}

.failure-content {
    text-align: left;
    color: #991b1b;
}

.failure-content > p:first-child {
    text-align: center;
    font-size: 1.5rem;
    font-weight: bold;
    color: #dc2626;
    margin-bottom: 2rem;
}

.violation-summary, .failure-explanation, .next-steps {
    background: white;
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 1.5rem;
    border-left: 4px solid #dc2626;
}

.violation-summary h3, .failure-explanation h3, .next-steps h3 {
    color: #dc2626;
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

.violation-summary ul, .next-steps ul {
    margin-left: 1.5rem;
    margin-bottom: 0;
}

.violation-summary li, .next-steps li {
    margin-bottom: 0.5rem;
    color: #374151;
}

.failure-actions {
    text-align: center;
    margin-top: 2rem;
}

.failure-actions .restart-btn {
    background: linear-gradient(135deg, #dc2626, #ef4444);
    font-size: 1.1rem;
    padding: 1rem 2rem;
}

.failure-actions .restart-btn:hover {
    background: linear-gradient(135deg, #b91c1c, #dc2626);
}

@keyframes pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.05); }
    100% { transform: scale(1); }
}

/* Footer Styles */
.site-footer {
    background: linear-gradient(135deg, #1e293b, #0f172a);
    color: white;
    padding: 2rem 0;
    margin-top: 4rem;
    border-top: 1px solid #334155;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.footer-links {
    display: flex;
    gap: 1.5rem;
}

.footer-link {
    color: #e2e8f0;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
    padding: 0.5rem 0;
}

.footer-link:hover {
    color: #60a5fa;
}

.footer-text {
    color: #94a3b8;
    font-size: 0.9rem;
}

.footer-text p {
    margin: 0;
}

/* Privacy Page Styles */
.privacy-container {
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem;
}

.privacy-header {
    text-align: center;
    margin-bottom: 3rem;
    padding: 2rem;
    background: linear-gradient(135deg, #1e40af, #3b82f6);
    color: white;
    border-radius: 12px;
}

.privacy-header h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
}

.privacy-subtitle {
    font-size: 1.2rem;
    opacity: 0.9;
    margin: 0;
}

.privacy-content {
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    overflow: hidden;
}

.privacy-section {
    padding: 2rem;
    border-bottom: 1px solid #e5e7eb;
}

.privacy-section:last-child {
    border-bottom: none;
}

.privacy-section h3 {
    color: #1e40af;
    font-size: 1.4rem;
    margin-bottom: 1rem;
    font-weight: 700;
}

.privacy-section p {
    line-height: 1.7;
    color: #374151;
    margin-bottom: 1rem;
}

.privacy-section p:last-child {
    margin-bottom: 0;
}

.highlight-box {
    background: linear-gradient(135deg, #dcfce7, #f0fdf4);
    border: 2px solid #16a34a;
    border-radius: 8px;
    padding: 1.5rem;
    margin: 1rem 0;
}

.highlight-box p {
    color: #166534;
    margin-bottom: 0.5rem;
}

.highlight-box p:last-child {
    margin-bottom: 0;
}

.privacy-list {
    list-style: none;
    padding-left: 0;
}

.privacy-list li {
    padding: 0.5rem 0;
    border-bottom: 1px solid #f3f4f6;
    color: #374151;
    line-height: 1.6;
}

.privacy-list li:last-child {
    border-bottom: none;
}

.privacy-list li strong {
    color: #1e40af;
}

.privacy-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-top: 2rem;
    flex-wrap: wrap;
}

.back-to-app-btn, .teacher-portal-btn {
    background: linear-gradient(135deg, #1e40af, #2563eb);
    color: white;
    text-decoration: none;
    padding: 1rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.back-to-app-btn:hover, .teacher-portal-btn:hover {
    background: linear-gradient(135deg, #1d4ed8, #3b82f6);
    transform: translateY(-2px);
    color: white;
}

@media (max-width: 768px) {
    .header-content h1 {
        font-size: 2rem;
    }
    
    .main-content {
        margin: 1rem auto;
        padding: 0 0.5rem;
    }
    
    .standard-card {
        padding: 1.5rem;
    }
    
    .standard-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
    }
    
    .info-content {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .background-info {
        padding: 1rem;
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
        gap: 1.5rem;
    }
    
    .privacy-container {
        padding: 1rem;
    }
    
    .privacy-header {
        padding: 1.5rem;
    }
    
    .privacy-header h2 {
        font-size: 2rem;
    }
    
    .privacy-section {
        padding: 1.5rem;
    }
    
    .privacy-actions {
        flex-direction: column;
        align-items: center;
    }
}

/* Unit Overview Styles */
.unit-overview {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

.unit-intro {
    text-align: center;
    margin-bottom: 3rem;
    padding: 2rem;
    background: linear-gradient(135deg, #1e40af, #3b82f6);
    color: white;
    border-radius: 12px;
}

.unit-intro h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
}

.unit-description {
    font-size: 1.2rem;
    opacity: 0.9;
    max-width: 800px;
    margin: 0 auto;
    line-height: 1.6;
}

.standards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.standard-title {
    font-size: 1.2rem;
    font-weight: 700;
    color: #1e40af;
    margin: 1rem 0;
}

.standard-text-box {
    background: linear-gradient(135deg, #eff6ff, #dbeafe);
    border: 2px solid #3b82f6;
    border-radius: 8px;
    padding: 1rem;
    margin: 1rem 0;
    font-size: 0.95rem;
    line-height: 1.5;
}

.standard-text-box strong {
    color: #1e40af;
    font-weight: 700;
}

.standard-badge.atoms {
    background: linear-gradient(135deg, #f8fafc, #e2e8f0);
    color: #1e293b;
}

.standard-badge.reactions {
    background: linear-gradient(135deg, #064e3b, #047857);
}

.standard-badge.materials {
    background: linear-gradient(135deg, #365314, #4d7c0f);
}

.standard-badge.thermal {
    background: linear-gradient(135deg, #0c4a6e, #0369a1);
}

.standard-badge.conservation {
    background: linear-gradient(135deg, #1e293b, #334155);
}

.standard-badge.completed {
    background: linear-gradient(135deg, #16a34a, #22c55e);
}

.standard-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 1.5rem;
    padding-top: 1rem;
    border-top: 1px solid #e5e7eb;
}

.questions-count {
    color: #6b7280;
    font-weight: 600;
    font-size: 0.9rem;
}

.start-indicator {
    color: #1e40af;
    font-weight: 600;
    font-size: 0.9rem;
}

.completed-indicator {
    color: #16a34a;
    font-weight: 600;
    font-size: 0.9rem;
}

.completed-standard {
    background: linear-gradient(135deg, #f0fdf4, #dcfce7);
    border: 2px solid #16a34a;
}

.completed-standard:hover {
    border-color: #15803d;
    box-shadow: 0 8px 16px rgba(22, 163, 74, 0.15);
}

.unit-progress {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
}

.unit-progress h3 {
    color: #1e40af;
    margin-bottom: 1.5rem;
    font-size: 1.5rem;
}

.progress-overview {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.progress-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem;
    border-radius: 8px;
    background: #f8fafc;
}

.progress-item.completed {
    background: #f0fdf4;
}

.progress-dot {
    width: 16px;
    height: 16px;
    border-radius: 50%;
    border: 2px solid #d1d5db;
    background: white;
}

.progress-dot.completed {
    background: #16a34a;
    border-color: #16a34a;
}

.progress-label {
    flex: 1;
    font-weight: 600;
    color: #374151;
}

.progress-status {
    font-size: 0.9rem;
    color: #6b7280;
    font-weight: 500;
}

.progress-item.completed .progress-status {
    color: #16a34a;
}

@media (max-width: 768px) {
    .standards-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .unit-overview {
        padding: 1rem;
    }
    
    .unit-intro {
        padding: 1.5rem;
    }
    
    .unit-intro h2 {
        font-size: 2rem;
    }
    
    .standard-footer {
        flex-direction: column;
        gap: 0.5rem;
        text-align: center;
    }
}

/* Standard-specific Styles */
.breadcrumb {
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
    color: #6b7280;
}

.breadcrumb a {
    color: #3b82f6;
    text-decoration: none;
}

.breadcrumb a:hover {
    text-decoration: underline;
}

.dci-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1rem;
}

.standard-section {
    background: #eff6ff;
    padding: 1.5rem;
    border-radius: 8px;
    margin: 1.5rem 0;
    border: 1px solid #dbeafe;
}

.standard-section h4 {
    color: #1e40af;
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

.standard-text {
    font-size: 1.1rem;
    line-height: 1.6;
    color: #1e3a8a;
    background: white;
    padding: 1rem;
    border-radius: 6px;
    border-left: 4px solid #2563eb;
}

.dci-item {
    padding: 1rem;
    background: #f8fafc;
    border-radius: 6px;
    border-left: 4px solid #3b82f6;
    font-size: 0.95rem;
    line-height: 1.6;
}

.learning-objectives {
    background: #f0f9ff;
    padding: 1.5rem;
    border-radius: 8px;
    margin: 1.5rem 0;
    border: 1px solid #e0f2fe;
}

.learning-objectives h4 {
    color: #0c4a6e;
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

.learning-objectives ul {
    list-style: none;
    padding-left: 0;
}

.learning-objectives li {
    padding: 0.5rem 0;
    position: relative;
    padding-left: 1.5rem;
}

.learning-objectives li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: #0891b2;
    font-weight: bold;
}

.key-concepts-section {
    background: #f0fdf4;
    padding: 1.5rem;
    border-radius: 8px;
    margin: 1.5rem 0;
    border: 1px solid #bbf7d0;
}

.key-concepts-section h4 {
    color: #166534;
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

.key-concepts-list {
    list-style: none;
    padding-left: 0;
}

.key-concepts-list li {
    padding: 0.75rem 0;
    border-bottom: 1px solid #dcfce7;
    position: relative;
    padding-left: 1.5rem;
}

.key-concepts-list li:last-child {
    border-bottom: none;
}

.key-concepts-list li::before {
    content: '🔑';
    position: absolute;
    left: 0;
    font-size: 1rem;
}

.key-concepts-list strong {
    color: #15803d;
}

.unit-navigation {
    text-align: center;
    padding: 3rem 2rem;
    background: linear-gradient(135deg, #f0f9ff, #e0f2fe);
    border-radius: 12px;
    border: 2px solid #0ea5e9;
    margin-top: 2rem;
}

.unit-navigation h3 {
    color: #0c4a6e;
    font-size: 2rem;
    margin-bottom: 2rem;
}

.nav-options {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.nav-btn {
    padding: 1rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-btn.primary {
    background: linear-gradient(135deg, #1e40af, #2563eb);
    color: white;
}

.nav-btn.primary:hover {
    background: linear-gradient(135deg, #1d4ed8, #3b82f6);
    transform: translateY(-2px);
    color: white;
}

.nav-btn.secondary {
    background: #f3f4f6;
    color: #374151;
    border: 2px solid #e5e7eb;
}

.nav-btn.secondary:hover {
    background: #e5e7eb;
    border-color: #d1d5db;
    color: #374151;
}

.celebration-timer {
    font-weight: bold;
    color: #16a34a;
}

.delay-timer {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.timer-icon {
    width: 12px;
    height: 12px;
    border: 2px solid #6b7280;
    border-top: 2px solid #dc2626;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

@media (max-width: 768px) {
    .nav-options {
        flex-direction: column;
        align-items: center;
    }
    
    .unit-navigation {
        padding: 2rem 1rem;
    }
    
    .unit-navigation h3 {
        font-size: 1.5rem;
    }
    
    .dci-grid {
        gap: 0.5rem;
    }
    
    .dci-item {
        padding: 0.75rem;
        font-size: 0.9rem;
    }
}

/* Coming Soon Styles */
.coming-soon-section {
    background: linear-gradient(135deg, #fef3c7, #fbbf24);
    padding: 2rem;
    border-radius: 12px;
    margin: 2rem 0;
    border: 2px solid #f59e0b;
    text-align: center;
}

.coming-soon-section h3 {
    color: #92400e;
    font-size: 1.8rem;
    margin-bottom: 1rem;
}

.coming-soon-section p {
    color: #92400e;
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
}

.coming-soon-section ul {
    text-align: left;
    max-width: 600px;
    margin: 0 auto 2rem auto;
    background: rgba(255, 255, 255, 0.8);
    padding: 1.5rem;
    border-radius: 8px;
}

.coming-soon-section li {
    color: #92400e;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.available-now {
    background: rgba(255, 255, 255, 0.9);
    padding: 1.5rem;
    border-radius: 8px;
    margin-top: 2rem;
}

.available-now h4 {
    color: #059669;
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

@media (max-width: 768px) {
    .coming-soon-section {
        padding: 1.5rem;
        margin: 1rem 0;
    }
    
    .coming-soon-section h3 {
        font-size: 1.5rem;
    }
}