/* CSS Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Color Palette */
    --color-primary: #E4C1F9;
    --color-secondary: #F6DFEB;
    --color-accent: #D0F4DE;
    --color-warning: #FCF6BD;
    --color-danger: #FFB7C5;
    --color-change: #36495f;
    
    /* Gradient Variations */
    --gradient-primary: linear-gradient(135deg, #E4C1F9 0%, #F6DFEB 100%);
    --gradient-secondary: linear-gradient(135deg, #D0F4DE 0%, #FCF6BD 100%);
    --gradient-accent: linear-gradient(135deg, #F6DFEB 0%, #FFB7C5 100%);
    --gradient-background: linear-gradient(135deg, #F6DFEB 0%, #E4C1F9 50%, #D0F4DE 100%);
    
    /* Text Colors */
    --text-primary: #2d3748;
    --text-secondary: #4a5568;
    --text-muted: #718096;
    --text-light: #ffffff;
    --text-change : #0b0b0c;
    
    /* Background Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f7fafc;
    --bg-overlay: rgba(0, 0, 0, 0.5);
    
    /* Border and Shadow */
    --border-color: #e2e8f0;
    --border-radius: 12px;
    --border-radius-large: 20px;
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.15);
    --shadow-lg: 0 8px 25px rgba(0, 0, 0, 0.2);
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Typography */
    --font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* Dark Theme Variables */
[data-theme="dark"] {
    --text-primary: #f7fafc;
    --text-secondary: #e2e8f0;
    --text-muted: #a0aec0;
    --bg-primary: #1a202c;
    --bg-secondary: #2d3748;
    --border-color: #4a5568;
    --gradient-background: linear-gradient(135deg, #2d3748 0%, #4a5568 50%, #1a202c 100%);
}

/* Base Styles */
html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--text-primary);
    background: var(--gradient-background);
    min-height: 100vh;
    transition: all var(--transition-normal);
}

/* App Container */
.app-container {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header Styles */
.header {
    background: var(--gradient-secondary);
    padding: var(--spacing-xl) var(--spacing-md);
    text-align: center;
    position: relative;
    box-shadow: var(--shadow-md);
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    position: relative;
}

.app-title {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    color: var(--text-change);
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.app-subtitle {
    font-size: var(--font-size-lg);
    color: var(--text-change);
    margin-bottom: var(--spacing-md);
    font-weight: 300;
}

.theme-toggle {
    position: absolute;
    top: 0;
    right: 0;
}

.theme-btn {
    background: rgba(255, 255, 255, 0.2);
    border: none;
    border-radius: 50%;
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    backdrop-filter: blur(10px);
}

.theme-btn:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: scale(1.05);
}

.theme-icon {
    font-size: var(--font-size-xl);
    transition: transform var(--transition-normal);
}

/* Main Content */
.main-content {
    flex: 1;
    padding: var(--spacing-xl) var(--spacing-md);
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
}

/* Form Styles */
.input-section {
    margin-bottom: var(--spacing-2xl);
}

.form-container {
    background: var(--bg-primary);
    border-radius: var(--border-radius-large);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
}

.form-container h2 {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-xl);
    text-align: center;
    color: var(--text-primary);
    font-weight: 600;
}

.weight-form {
    display: grid;
    gap: var(--spacing-lg);
}

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

.input-label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: var(--font-size-base);
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.required {
    color: var(--color-danger);
    font-weight: 700;
}

.optional {
    color: var(--text-muted);
    font-size: var(--font-size-sm);
    font-weight: 400;
}

.form-input,
.form-select {
    padding: var(--spacing-md);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: var(--font-size-base);
    background: var(--bg-primary);
    color: var(--text-primary);
    transition: all var(--transition-normal);
    width: 100%;
}
.unit-select {
    padding: var(--spacing-md);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: var(--font-size-base);
    background: var(--bg-primary);
    color: var(--text-primary);
    transition: all var(--transition-normal);
    width: auto;
}

.form-input:focus,
.form-select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(228, 193, 249, 0.1);
}

.form-input:invalid:not(:placeholder-shown) {
    border-color: var(--color-danger);
}

.input-with-unit {
    display: flex;
    gap: var(--spacing-sm);
    align-items: center;
}

.input-with-unit .form-input {
    flex: 1;
}

.unit-select {
    min-width: 80px;
    flex-shrink: 0;
}

.unit-text {
    color: var(--text-muted);
    font-weight: 500;
    min-width: 30px;
    text-align: center;
}

.input-help {
    font-size: var(--font-size-sm);
    color: var(--text-muted);
    margin-top: var(--spacing-xs);
}

.error-message {
    color: var(--color-danger);
    font-size: var(--font-size-sm);
    font-weight: 500;
    min-height: 1.2em;
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.error-message:before {
    content: "⚠️";
    font-size: var(--font-size-xs);
}

/* Gender Radio Buttons */
.gender-fieldset {
    border: none;
    padding: 0;
}

.radio-group {
    display: flex;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-sm);
}

.radio-label {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    cursor: pointer;
    padding: var(--spacing-sm);
    border-radius: var(--border-radius);
    transition: all var(--transition-normal);
    flex: 1;
    justify-content: center;
    border: 2px solid var(--border-color);
}

.radio-label:hover {
    background: rgba(228, 193, 249, 0.1);
    border-color: var(--color-primary);
}

.radio-input {
    display: none;
}

.radio-custom {
    width: 20px;
    height: 20px;
    border: 2px solid var(--border-color);
    border-radius: 50%;
    position: relative;
    transition: all var(--transition-normal);
}

.radio-input:checked + .radio-custom {
    border-color: var(--color-primary);
    background: var(--color-primary);
}

.radio-input:checked + .radio-custom:after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 8px;
    height: 8px;
    background: white;
    border-radius: 50%;
}

.radio-text {
    font-weight: 500;
    color: var(--text-primary);
}

/* Buttons */
.btn {
    padding: var(--spacing-md) var(--spacing-lg);
    border: none;
    border-radius: var(--border-radius);
    font-size: var(--font-size-base);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    text-decoration: none;
    min-height: 48px;
    position: relative;
    overflow: hidden;
}

.btn:before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s;
}

.btn:hover:before {
    left: 100%;
}

.btn-primary {
    background: var(--gradient-primary);
    color: var(--text-change);
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: var(--gradient-secondary);
    color: var(--text-primary);
    box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-outline {
    background: transparent;
    color: var(--text-primary);
    border: 2px solid var(--border-color);
}

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

.btn-small {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-sm);
    min-height: 36px;
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none !important;
}

.btn-icon {
    font-size: var(--font-size-lg);
}

.form-actions {
    display: flex;
    justify-content: center;
    margin-top: var(--spacing-xl);
}

.form-actions .btn {
    min-width: 200px;
}

/* Results Section */
.results-section {
    margin-bottom: var(--spacing-2xl);
    animation: slideInUp 0.5s ease-out;
}

.results-container {
    background: var(--bg-primary);
    border-radius: var(--border-radius-large);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
}

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

.results-header h2 {
    font-size: var(--font-size-2xl);
    color: var(--text-primary);
    font-weight: 600;
}

.results-actions {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.results-grid {
    display: grid;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.result-card {
    background: var(--gradient-accent);
    border-radius: var(--border-radius);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-normal);
    border: 1px solid var(--border-color);
    animation: fadeInScale 0.5s ease-out;
}

.result-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.result-card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-md);
}

.result-title {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--text-primary);
}

.result-icon {
    font-size: var(--font-size-xl);
}

.result-value {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.result-description {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    line-height: 1.5;
}

.result-status {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--border-radius);
    font-size: var(--font-size-sm);
    font-weight: 500;
    margin-top: var(--spacing-sm);
}

.status-healthy {
    background: var(--color-accent);
    color: var(--text-primary);
}

.status-warning {
    background: var(--color-warning);
    color: var(--text-primary);
}

.status-danger {
    background: var(--color-danger);
    color: var(--text-primary);
}

/* Recommendations */
.recommendations {
    background: var(--gradient-secondary);
    border-radius: var(--border-radius);
    padding: var(--spacing-lg);
    border: 1px solid var(--border-color);
}

.recommendations h3 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
    font-weight: 600;
}

.recommendation-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.recommendation-item {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm);
    background: rgba(255, 255, 255, 0.5);
    border-radius: var(--border-radius);
}

.recommendation-icon {
    font-size: var(--font-size-lg);
    flex-shrink: 0;
}

.recommendation-text {
    color: var(--text-secondary);
    line-height: 1.5;
}

/* History Section */
.history-section {
    margin-bottom: var(--spacing-2xl);
}

.history-container {
    background: var(--bg-primary);
    border-radius: var(--border-radius-large);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
}

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

.history-header h3 {
    font-size: var(--font-size-xl);
    color: var(--text-primary);
    font-weight: 600;
}

.history-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.history-item {
    background: var(--bg-secondary);
    border-radius: var(--border-radius);
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
    cursor: pointer;
}

.history-item:hover {
    background: var(--color-secondary);
    transform: translateX(4px);
}

.history-item-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-sm);
}

.history-date {
    font-size: var(--font-size-sm);
    color: var(--text-muted);
    font-weight: 500;
}

.history-summary {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    line-height: 1.4;
}

.history-empty {
    text-align: center;
    color: var(--text-muted);
    font-style: italic;
    padding: var(--spacing-xl);
}

/* FAQ Section */
.faq-section {
    margin-bottom: var(--spacing-2xl);
}

.faq-container {
    max-width: 800px;
    margin: 0 auto;
    background: var(--bg-primary);
    border-radius: var(--border-radius-large);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
}

.faq-container h2 {
    font-size: var(--font-size-2xl);
    text-align: center;
    margin-bottom: var(--spacing-xl);
    color: var(--text-primary);
    font-weight: 600;
}

.faq-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.faq-item {
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    overflow: hidden;
    transition: all var(--transition-normal);
}

.faq-item:hover {
    box-shadow: var(--shadow-sm);
}

.faq-question {
    background: var(--gradient-secondary);
    padding: var(--spacing-md);
    cursor: pointer;
    font-weight: 600;
    color: var(--text-change);
    list-style: none;
    transition: all var(--transition-normal);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.faq-question::-webkit-details-marker {
    display: none;
}

.faq-question:after {
    content: '+';
    font-size: var(--font-size-xl);
    font-weight: 700;
    transition: transform var(--transition-normal);
}

details[open] .faq-question:after {
    transform: rotate(45deg);
}

.faq-answer {
    padding: var(--spacing-md);
    background: var(--bg-primary);
    border-top: 1px solid var(--border-color);
    animation: fadeIn 0.3s ease-out;
}

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

/* Loading Overlay */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--bg-overlay);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    backdrop-filter: blur(5px);
}

.loading-spinner {
    background: var(--bg-primary);
    border-radius: var(--border-radius-large);
    padding: var(--spacing-xl);
    text-align: center;
    box-shadow: var(--shadow-lg);
    max-width: 300px;
    width: 90%;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--color-primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto var(--spacing-md);
}

.loading-spinner p {
    color: var(--text-primary);
    font-weight: 500;
}

/* Toast Notifications */
.toast-container {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 1001;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.toast {
    background: var(--bg-primary);
    border-radius: var(--border-radius);
    padding: var(--spacing-md);
    box-shadow: var(--shadow-lg);
    border-left: 4px solid var(--color-primary);
    min-width: 300px;
    max-width: 400px;
    animation: slideInRight 0.3s ease-out;
    position: relative;
}

.toast.success {
    border-left-color: var(--color-accent);
}

.toast.error {
    border-left-color: var(--color-danger);
}

.toast.warning {
    border-left-color: var(--color-warning);
}

.toast-content {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.toast-icon {
    font-size: var(--font-size-lg);
    flex-shrink: 0;
}

.toast-message {
    color: var(--text-primary);
    font-weight: 500;
    flex: 1;
}

.toast-close {
    background: none;
    border: none;
    font-size: var(--font-size-lg);
    cursor: pointer;
    color: var(--text-muted);
    padding: 0;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    transition: all var(--transition-fast);
}

.toast-close:hover {
    background: var(--border-color);
    color: var(--text-primary);
}

/* Footer */
.footer {
    background: var(--gradient-primary);
    padding: var(--spacing-lg) var(--spacing-md);
    text-align: center;
    border-top: 1px solid var(--border-color);
    margin-top: auto;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
}

.footer p {
    color: var(--text-change);
    font-size: var(--font-size-sm);
    margin: 0;
}

.footer a {
    color: var(--text-change);
    text-decoration: none;
    font-weight: 600;
    transition: all var(--transition-normal);
}

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

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

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

@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(100%);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes spin {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .header {
        padding: var(--spacing-lg) var(--spacing-md);
    }
    
    .app-title {
        font-size: var(--font-size-2xl);
    }
    
    .app-subtitle {
        font-size: var(--font-size-base);
    }
    
    .theme-toggle {
        position: static;
        margin-top: var(--spacing-md);
    }
    
    .main-content {
        padding: var(--spacing-lg) var(--spacing-md);
    }
    
    .form-container,
    .results-container,
    .history-container,
    .faq-container {
        padding: var(--spacing-lg);
    }
    
    .results-header {
        flex-direction: column;
        align-items: stretch;
    }
    
    .results-actions {
        justify-content: center;
    }
    
    .radio-group {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
    
    .history-header {
        flex-direction: column;
        align-items: stretch;
    }
    
    .toast-container {
        left: 10px;
        right: 10px;
        top: 10px;
    }
    
    .toast {
        min-width: auto;
        max-width: none;
    }
    
    .form-actions .btn {
        min-width: auto;
        width: 100%;
    }
}

@media (max-width: 480px) {
    .app-title {
        font-size: var(--font-size-xl);
    }
    
    .form-container,
    .results-container,
    .history-container,
    .faq-container {
        padding: var(--spacing-md);
    }
    
    .btn {
        padding: var(--spacing-sm) var(--spacing-md);
        font-size: var(--font-size-sm);
    }
    
    .results-actions {
        flex-direction: column;
    }
    
    .input-with-unit {
        flex-direction: column;
        align-items: stretch;
    }
    
    .unit-select {
        min-width: auto;
    }
}

@media (min-width: 769px) {
    .results-grid {
        grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    }
    
    .weight-form {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-lg) var(--spacing-xl);
    }
    
    .weight-form .form-actions {
        grid-column: 1 / -1;
    }
    
    .radio-group {
        justify-content: center;
        max-width: 400px;
        margin: var(--spacing-sm) auto 0;
    }
}

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

/* Print Styles */
@media print {
    .header,
    .footer,
    .theme-toggle,
    .results-actions,
    .history-section,
    .faq-section,
    .toast-container,
    .loading-overlay {
        display: none !important;
    }
    
    .app-container {
        background: var(--bg-primary);
    }
    
    .results-section {
        break-inside: avoid;
    }
    
    .result-card {
        break-inside: avoid;
        box-shadow: none;
        border: 1px solid #ccc;
    }
}

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

@media (prefers-contrast: high) {
    :root {
        --border-color: #000;
        --text-muted: #333;
        --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.3);
        --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
        --shadow-lg: 0 8px 25px rgba(0, 0, 0, 0.5);
    }
}

/* Focus Styles for Accessibility */
*:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.btn:focus,
.form-input:focus,
.form-select:focus {
    outline: 3px solid var(--color-primary);
    outline-offset: 2px;
}

/* Screen Reader Only Content */
/* The .sr-only class hides elements visually while keeping them accessible to screen readers. */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}