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

:root {
    --primary-white: #FFFFFF;
    --light-gray: #F8F9FA;
    --medium-gray: #E9ECEF;
    --dark-gray: #6C757D;
    --primary-dark: #212529;
    --accent-blue: #007bff;
    --success-green: #28a745;
    --warning-orange: #fd7e14;
    --danger-red: #dc3545;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--light-gray);
    color: var(--primary-dark);
    line-height: 1.6;
    padding-bottom: 80px;
}

.app-header {
    background: linear-gradient(135deg, var(--accent-blue), #0056b3);
    color: var(--primary-white);
    padding: 1rem;
    text-align: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

.app-header h1 {
    font-size: 1.5rem;
    font-weight: 600;
    margin: 0;
}

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

.content-section {
    display: none;
    animation: fadeIn 0.3s ease-in;
}

.content-section.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Calculator Styles */
.calculator-container {
    background: var(--primary-white);
    border-radius: 15px;
    padding: 1.5rem;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
    border: 2px solid var(--medium-gray);
    position: relative;
}

.calculator-container::before {
    content: '';
    position: absolute;
    top: -2px;
    left: -2px;
    right: -2px;
    bottom: -2px;
    background: linear-gradient(45deg, var(--accent-blue), var(--success-green));
    border-radius: 17px;
    z-index: -1;
    opacity: 0.1;
}

.calculator-container h2 {
    color: var(--primary-dark);
    margin-bottom: 1.5rem;
    font-size: 1.3rem;
    text-align: center;
}

.investment-form {
    display: grid;
    gap: 1rem;
}

.form-group {
    display: flex;
    flex-direction: column;
}

.form-group label {
    color: var(--dark-gray);
    font-weight: 500;
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
}

.form-group input {
    padding: 0.75rem;
    border: 2px solid var(--medium-gray);
    border-radius: 8px;
    font-size: 1rem;
    transition: all 0.3s ease;
    background: var(--light-gray);
}

.form-group input:focus {
    outline: none;
    border-color: var(--accent-blue);
    background: var(--primary-white);
    box-shadow: 0 0 0 3px rgba(0,123,255,0.1);
}

.calculate-btn {
    background: linear-gradient(135deg, var(--accent-blue), #0056b3);
    color: var(--primary-white);
    border: none;
    padding: 1rem;
    border-radius: 10px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.calculate-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0,123,255,0.3);
}

.calculate-btn:active {
    transform: translateY(0);
}

/* Results Styles */
.results-container {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 2px dashed var(--medium-gray);
}

.results-container h3 {
    color: var(--primary-dark);
    margin-bottom: 1.5rem;
    text-align: center;
    font-size: 1.2rem;
}

.results-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.result-card {
    background: var(--light-gray);
    border: 2px solid var(--medium-gray);
    border-radius: 10px;
    padding: 1rem;
    text-align: center;
    transition: all 0.3s ease;
}

.result-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    border-color: var(--accent-blue);
}

.result-label {
    font-size: 0.8rem;
    color: var(--dark-gray);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.result-value {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--primary-dark);
}

.result-value.positive {
    color: var(--success-green);
}

.result-value.negative {
    color: var(--danger-red);
}

.save-analysis {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.save-analysis input {
    flex: 1;
    padding: 0.75rem;
    border: 2px solid var(--medium-gray);
    border-radius: 8px;
    font-size: 1rem;
    min-width: 200px;
}

.save-btn {
    background: var(--success-green);
    color: var(--primary-white);
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    white-space: nowrap;
}

.save-btn:hover {
    background: #218838;
    transform: translateY(-1px);
}

/* History Styles */
.history-container, .compare-container, .notes-container, .faq-container {
    background: var(--primary-white);
    border-radius: 15px;
    padding: 1.5rem;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
}

.history-container h2, .compare-container h2, .notes-container h2, .faq-container h2 {
    color: var(--primary-dark);
    margin-bottom: 1.5rem;
    font-size: 1.3rem;
    text-align: center;
}

.analyses-list {
    display: grid;
    gap: 1rem;
}

.analysis-item {
    background: var(--light-gray);
    border: 2px solid var(--medium-gray);
    border-radius: 10px;
    padding: 1rem;
    transition: all 0.3s ease;
}

.analysis-item:hover {
    border-color: var(--accent-blue);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

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

.analysis-name {
    font-weight: 600;
    color: var(--primary-dark);
    font-size: 1.1rem;
}

.analysis-date {
    font-size: 0.8rem;
    color: var(--dark-gray);
}

.analysis-summary {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(100px, 1fr));
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.summary-item {
    text-align: center;
}

.summary-label {
    font-size: 0.7rem;
    color: var(--dark-gray);
    margin-bottom: 0.2rem;
}

.summary-value {
    font-weight: 600;
    color: var(--primary-dark);
    font-size: 0.9rem;
}

.analysis-actions {
    display: flex;
    gap: 0.5rem;
    justify-content: flex-end;
}

.btn-small {
    padding: 0.4rem 0.8rem;
    border: none;
    border-radius: 6px;
    font-size: 0.8rem;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 0.3rem;
}

.btn-compare {
    background: var(--accent-blue);
    color: var(--primary-white);
}

.btn-compare:hover {
    background: #0056b3;
}

.btn-delete {
    background: var(--danger-red);
    color: var(--primary-white);
}

.btn-delete:hover {
    background: #c82333;
}

.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--dark-gray);
}

.empty-state i {
    font-size: 3rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

.empty-state p {
    margin-bottom: 0.5rem;
}

/* Comparison Styles */
.comparison-area {
    min-height: 300px;
}

.comparison-empty {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--dark-gray);
}

.comparison-empty i {
    font-size: 3rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

.comparison-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
}

.comparison-item {
    background: var(--light-gray);
    border: 2px solid var(--medium-gray);
    border-radius: 10px;
    padding: 1rem;
}

.comparison-header {
    text-align: center;
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--medium-gray);
}

.comparison-name {
    font-weight: 600;
    color: var(--primary-dark);
    margin-bottom: 0.3rem;
}

.comparison-metrics {
    display: grid;
    gap: 0.5rem;
}

.metric-row {
    display: flex;
    justify-content: space-between;
    padding: 0.3rem 0;
    border-bottom: 1px solid var(--medium-gray);
}

.metric-label {
    font-size: 0.9rem;
    color: var(--dark-gray);
}

.metric-value {
    font-weight: 600;
    color: var(--primary-dark);
}

/* Notes Styles */
.add-note {
    background: var(--light-gray);
    border-radius: 10px;
    padding: 1rem;
    margin-bottom: 1.5rem;
    border: 2px solid var(--medium-gray);
}

.add-note input, .add-note textarea {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--medium-gray);
    border-radius: 8px;
    font-size: 1rem;
    margin-bottom: 0.5rem;
    font-family: inherit;
}

.add-note textarea {
    min-height: 100px;
    resize: vertical;
}

.add-note input:focus, .add-note textarea:focus {
    outline: none;
    border-color: var(--accent-blue);
    box-shadow: 0 0 0 3px rgba(0,123,255,0.1);
}

.add-note-btn {
    background: var(--accent-blue);
    color: var(--primary-white);
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.add-note-btn:hover {
    background: #0056b3;
    transform: translateY(-1px);
}

.notes-list {
    display: grid;
    gap: 1rem;
}

.note-item {
    background: var(--light-gray);
    border: 2px solid var(--medium-gray);
    border-radius: 10px;
    padding: 1rem;
    transition: all 0.3s ease;
}

.note-item:hover {
    border-color: var(--accent-blue);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.note-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
}

.note-title {
    font-weight: 600;
    color: var(--primary-dark);
    font-size: 1.1rem;
}

.note-date {
    font-size: 0.8rem;
    color: var(--dark-gray);
}

.note-content {
    color: var(--primary-dark);
    line-height: 1.6;
    margin-bottom: 1rem;
    white-space: pre-wrap;
}

.note-actions {
    display: flex;
    gap: 0.5rem;
    justify-content: flex-end;
}

.btn-edit {
    background: var(--warning-orange);
    color: var(--primary-white);
}

.btn-edit:hover {
    background: #e06b00;
}

/* FAQ Styles */
.faq-item {
    border: 2px solid var(--medium-gray);
    border-radius: 10px;
    margin-bottom: 1rem;
    overflow: hidden;
    transition: all 0.3s ease;
}

.faq-item:hover {
    border-color: var(--accent-blue);
}

.faq-question {
    width: 100%;
    background: var(--light-gray);
    border: none;
    padding: 1rem;
    text-align: left;
    font-size: 1rem;
    font-weight: 600;
    color: var(--primary-dark);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: all 0.3s ease;
}

.faq-question:hover {
    background: var(--medium-gray);
}

.faq-question[aria-expanded="true"] {
    background: var(--accent-blue);
    color: var(--primary-white);
}

.faq-icon {
    font-size: 1.2rem;
    font-weight: bold;
    transition: transform 0.3s ease;
}

.faq-question[aria-expanded="true"] .faq-icon {
    transform: rotate(45deg);
}

.faq-answer {
    background: var(--primary-white);
    padding: 0;
    max-height: 0;
    overflow: hidden;
    transition: all 0.3s ease;
}

.faq-answer:not([hidden]) {
    padding: 1rem;
    max-height: 200px;
}

.faq-answer p {
    color: var(--primary-dark);
    line-height: 1.6;
    margin: 0;
}

/* Bottom Navigation */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--primary-white);
    border-top: 2px solid var(--medium-gray);
    display: flex;
    justify-content: space-around;
    padding: 0.5rem 0;
    z-index: 1000;
    box-shadow: 0 -2px 10px rgba(0,0,0,0.1);
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-decoration: none;
    color: var(--dark-gray);
    padding: 0.5rem;
    border-radius: 8px;
    transition: all 0.3s ease;
    min-width: 60px;
}

.nav-item:hover {
    background: var(--light-gray);
    color: var(--accent-blue);
}

.nav-item.active {
    color: var(--accent-blue);
    background: rgba(0,123,255,0.1);
}

.nav-item i {
    font-size: 1.2rem;
    margin-bottom: 0.2rem;
}

.nav-item span {
    font-size: 0.7rem;
    font-weight: 500;
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem 1rem;
    color: var(--dark-gray);
    font-size: 0.9rem;
    background: var(--primary-white);
    border-top: 1px solid var(--medium-gray);
    margin-top: 2rem;
}

/* Responsive Design */
@media (min-width: 768px) {
    .main-content {
        padding: 2rem;
    }
    
    .calculator-container, .history-container, .compare-container, .notes-container, .faq-container {
        padding: 2rem;
    }
    
    .investment-form {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.5rem;
    }
    
    .calculate-btn {
        grid-column: 1 / -1;
    }
    
    .results-grid {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .app-header h1 {
        font-size: 2rem;
    }
    
    .bottom-nav {
        display: none;
    }
    
    body {
        padding-bottom: 0;
    }
    
    .main-content::before {
        content: '';
        position: fixed;
        top: 0;
        left: 0;
        width: 200px;
        height: 100vh;
        background: var(--primary-white);
        border-right: 2px solid var(--medium-gray);
        z-index: 999;
    }
    
    .desktop-nav {
        position: fixed;
        top: 100px;
        left: 0;
        width: 200px;
        padding: 1rem;
        z-index: 1000;
    }
    
    .desktop-nav .nav-item {
        width: 100%;
        flex-direction: row;
        justify-content: flex-start;
        padding: 1rem;
        margin-bottom: 0.5rem;
        text-decoration: none;
        color: var(--dark-gray);
        border-radius: 8px;
        transition: all 0.3s ease;
    }
    
    .desktop-nav .nav-item i {
        margin-right: 0.5rem;
        margin-bottom: 0;
    }
    
    .desktop-nav .nav-item span {
        font-size: 1rem;
    }
    
    .main-content {
        margin-left: 200px;
        width: calc(100% - 200px);
    }
}

@media (min-width: 1024px) {
    .results-grid {
        grid-template-columns: repeat(6, 1fr);
    }
    
    .comparison-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

/* Loading States */
.loading {
    opacity: 0.6;
    pointer-events: none;
}

.loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 20px;
    height: 20px;
    margin: -10px 0 0 -10px;
    border: 2px solid var(--medium-gray);
    border-top: 2px solid var(--accent-blue);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

/* Error States */
.error {
    background: #f8d7da;
    border-color: var(--danger-red);
    color: #721c24;
}

.success {
    background: #d4edda;
    border-color: var(--success-green);
    color: #155724;
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus styles for keyboard navigation */
button:focus, input:focus, textarea:focus, .nav-item:focus {
    outline: 2px solid var(--accent-blue);
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --medium-gray: #000000;
        --dark-gray: #000000;
    }
}