/* ================================
   CSS CUSTOM PROPERTIES (Variables)
   ================================ */
:root {
    /* Colors */
    --primary-color: #1E3A8A;
    --secondary-color: #F59E0B;
    --background-color: #F3F4F6;
    --surface-color: #FFFFFF;
    --text-primary: #111827;
    --text-secondary: #6B7280;
    --text-muted: #9CA3AF;
    --border-color: #E5E7EB;
    --hover-color: #F9FAFB;
    --success-color: #10B981;
    --warning-color: #F59E0B;
    --error-color: #EF4444;
    --info-color: #3B82F6;
    
    /* Dark mode colors */
    --dark-background: #0F172A;
    --dark-surface: #1E293B;
    --dark-text-primary: #F1F5F9;
    --dark-text-secondary: #CBD5E1;
    --dark-text-muted: #94A3B8;
    --dark-border: #334155;
    --dark-hover: #2D3748;
    
    /* 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: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 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: 1.875rem;
    --font-size-4xl: 2.25rem;
    
    /* Layout */
    --container-max-width: 1200px;
    --sidebar-width: 280px;
    --header-height: 70px;
    --bottom-nav-height: 70px;
    
    /* Border radius */
    --border-radius-sm: 0.375rem;
    --border-radius-md: 0.5rem;
    --border-radius-lg: 0.75rem;
    --border-radius-xl: 1rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;
}

/* Dark mode theme */
[data-theme="dark"] {
    --background-color: var(--dark-background);
    --surface-color: var(--dark-surface);
    --text-primary: var(--dark-text-primary);
    --text-secondary: var(--dark-text-secondary);
    --text-muted: var(--dark-text-muted);
    --border-color: var(--dark-border);
    --hover-color: var(--dark-hover);
}

/* ================================
   RESET & BASE STYLES
   ================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    height: 100%;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--background-color);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

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

/* Skip to main content */
.skip-to-main {
    position: absolute;
    top: -40px;
    left: 6px;
    background: var(--primary-color);
    color: white;
    padding: 8px;
    text-decoration: none;
    border-radius: var(--border-radius-md);
    z-index: 1000;
    transition: top var(--transition-fast);
}

.skip-to-main:focus {
    top: 6px;
}

/* ================================
   LOADING SCREEN
   ================================ */
.loading-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--background-color);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    transition: opacity var(--transition-slow), visibility var(--transition-slow);
}

.loading-screen.hidden {
    opacity: 0;
    visibility: hidden;
}

.loading-spinner {
    position: relative;
    margin-bottom: var(--spacing-lg);
}

.loading-spinner i {
    color: var(--primary-color);
    animation: pulse 2s infinite;
}

.spinner {
    position: absolute;
    top: -10px;
    left: -10px;
    width: 60px;
    height: 60px;
    border: 3px solid transparent;
    border-top: 3px solid var(--secondary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

/* ================================
   HEADER
   ================================ */
.header {
    background: var(--surface-color);
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 1000;
    height: var(--header-height);
}

.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--header-height);
}

.logo-section {
    display: flex;
    flex-direction: column;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
}

.logo i {
    font-size: var(--font-size-2xl);
}

.tagline {
    font-size: var(--font-size-xs);
    color: var(--text-secondary);
    margin-top: -2px;
}

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

.search-container {
    position: relative;
    display: none;
}

.search-container input {
    padding: var(--spacing-sm) var(--spacing-md) var(--spacing-sm) 2.5rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    background: var(--surface-color);
    color: var(--text-primary);
    font-size: var(--font-size-sm);
    width: 250px;
    transition: all var(--transition-fast);
}

.search-container input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(30, 58, 138, 0.1);
}

.search-icon {
    position: absolute;
    left: var(--spacing-sm);
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
}

.theme-toggle, .menu-toggle {
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: var(--font-size-lg);
    cursor: pointer;
    padding: var(--spacing-sm);
    border-radius: var(--border-radius-md);
    transition: all var(--transition-fast);
}

.theme-toggle:hover, .menu-toggle:hover {
    background: var(--hover-color);
    color: var(--primary-color);
}

.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 3px;
    padding: var(--spacing-sm);
}

.menu-toggle span {
    width: 20px;
    height: 2px;
    background: currentColor;
    transition: all var(--transition-fast);
}

.menu-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.menu-toggle.active span:nth-child(2) {
    opacity: 0;
}

.menu-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -6px);
}

/* ================================
   SIDEBAR NAVIGATION
   ================================ */
.sidebar {
    position: fixed;
    top: var(--header-height);
    left: 0;
    width: var(--sidebar-width);
    height: calc(100vh - var(--header-height));
    background: var(--surface-color);
    border-right: 1px solid var(--border-color);
    overflow-y: auto;
    transition: transform var(--transition-normal);
    z-index: 999;
}

.sidebar-header {
    padding: var(--spacing-lg) var(--spacing-md);
    border-bottom: 1px solid var(--border-color);
}

.sidebar-header h2 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--text-primary);
}

.nav-list {
    list-style: none;
    padding: var(--spacing-md) 0;
}

.nav-list li {
    margin-bottom: var(--spacing-xs);
}

.nav-category {
    margin-top: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
}

.nav-category span {
    font-size: var(--font-size-xs);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
    border-bottom: 1px solid var(--border-color);
    padding-bottom: var(--spacing-xs);
    display: block;
}

.nav-category:first-child {
    margin-top: 0;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md);
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: all var(--transition-fast);
    border-radius: 0 var(--border-radius-lg) var(--border-radius-lg) 0;
    margin-right: var(--spacing-md);
}

.nav-link:hover {
    background: var(--hover-color);
    color: var(--primary-color);
}

.nav-link.active {
    background: rgba(30, 58, 138, 0.1);
    color: var(--primary-color);
    border-right: 3px solid var(--primary-color);
}

.nav-link i {
    width: 20px;
    text-align: center;
}

/* ================================
   MAIN CONTENT
   ================================ */
.main-content {
    flex: 1;
    margin-left: var(--sidebar-width);
    padding: var(--spacing-xl) 0;
    min-height: calc(100vh - var(--header-height));
}

.calculator-container {
    background: var(--surface-color);
    border-radius: var(--border-radius-xl);
    box-shadow: var(--shadow-lg);
    padding: var(--spacing-2xl);
    margin-bottom: var(--spacing-xl);
    transition: all var(--transition-normal);
}

.calculator-container:hover {
    box-shadow: var(--shadow-xl);
}

/* ================================
   CALCULATOR COMPONENTS
   ================================ */
.calculator {
    display: none;
    animation: fadeIn var(--transition-normal);
}

.calculator.active {
    display: block;
}

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

.calculator-header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.calculator-title {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
}

.calculator-description {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
}

/* Button Styles */
.btn {
    padding: var(--spacing-sm) var(--spacing-md);
    border: none;
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-base);
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    position: relative;
    overflow: hidden;
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

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

.btn-primary:hover:not(:disabled) {
    background: #1E40AF;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: var(--surface-color);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover:not(:disabled) {
    background: var(--hover-color);
    border-color: var(--primary-color);
}

.btn-accent {
    background: var(--secondary-color);
    color: white;
}

.btn-accent:hover:not(:disabled) {
    background: #D97706;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

/* Ripple effect for buttons */
.btn::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.3);
    transform: translate(-50%, -50%);
    transition: width var(--transition-fast), height var(--transition-fast);
}

.btn:active::after {
    width: 300px;
    height: 300px;
}

/* Form Elements */
.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-label {
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 500;
    color: var(--text-primary);
}

.form-input {
    width: 100%;
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    background: var(--surface-color);
    color: var(--text-primary);
    font-size: var(--font-size-base);
    transition: all var(--transition-fast);
}

.form-input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(30, 58, 138, 0.1);
}

.form-input:invalid {
    border-color: var(--error-color);
}

/* Grid Layouts */
.grid {
    display: grid;
    gap: var(--spacing-md);
}

.grid-2 {
    grid-template-columns: repeat(2, 1fr);
}

.grid-3 {
    grid-template-columns: repeat(3, 1fr);
}

.grid-4 {
    grid-template-columns: repeat(4, 1fr);
}

/* Calculator Display */
.calculator-display {
    background: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    font-family: 'Courier New', monospace;
    font-size: var(--font-size-2xl);
    font-weight: 600;
    text-align: right;
    min-height: 80px;
    display: flex;
    align-items: center;
    justify-content: flex-end;
    word-break: break-all;
    overflow-wrap: break-word;
}

/* Calculator Buttons Grid */
.calc-buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-sm);
    margin-top: var(--spacing-lg);
}

.calc-btn {
    padding: var(--spacing-lg);
    font-size: var(--font-size-xl);
    font-weight: 600;
    min-height: 60px;
    border-radius: var(--border-radius-md);
    transition: all var(--transition-fast);
}

.calc-btn-number {
    background: var(--surface-color);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.calc-btn-operator {
    background: var(--primary-color);
    color: white;
}

.calc-btn-function {
    background: var(--secondary-color);
    color: white;
}

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

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

/* Results Section */
.results-section {
    background: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

.result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) 0;
    border-bottom: 1px solid var(--border-color);
}

.result-item:last-child {
    border-bottom: none;
}

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

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

/* Chart Container */
.chart-container {
    margin-top: var(--spacing-xl);
    padding: var(--spacing-lg);
    background: var(--surface-color);
    border-radius: var(--border-radius-lg);
    border: 1px solid var(--border-color);
    height: 400px;
}

/* ================================
   HISTORY PANEL
   ================================ */
.history-panel {
    position: fixed;
    top: var(--header-height);
    right: -350px;
    width: 350px;
    height: calc(100vh - var(--header-height));
    background: var(--surface-color);
    border-left: 1px solid var(--border-color);
    box-shadow: var(--shadow-xl);
    transition: right var(--transition-normal);
    z-index: 998;
    display: flex;
    flex-direction: column;
}

.history-panel.open {
    right: 0;
}

.history-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.history-actions {
    display: flex;
    gap: var(--spacing-xs);
}

.history-list {
    flex: 1;
    overflow-y: auto;
    padding: var(--spacing-md);
}

.history-item {
    padding: var(--spacing-md);
    border-radius: var(--border-radius-md);
    margin-bottom: var(--spacing-sm);
    background: var(--background-color);
    border: 1px solid var(--border-color);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.history-item:hover {
    background: var(--hover-color);
    border-color: var(--primary-color);
}

.history-calculation {
    font-family: 'Courier New', monospace;
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
}

.history-result {
    font-weight: 600;
    color: var(--primary-color);
}

.history-timestamp {
    font-size: var(--font-size-xs);
    color: var(--text-muted);
    margin-top: var(--spacing-xs);
}

/* ================================
   BOTTOM NAVIGATION (Mobile)
   ================================ */
.bottom-nav {
    display: none;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--surface-color);
    border-top: 1px solid var(--border-color);
    padding: var(--spacing-xs) 0;
    z-index: 1000;
}

.bottom-nav-item {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--spacing-xs);
    text-decoration: none;
    color: var(--text-secondary);
    font-size: var(--font-size-xs);
    transition: all var(--transition-fast);
}

.bottom-nav-item.active {
    color: var(--primary-color);
}

.bottom-nav-item i {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-xs);
}

/* ================================
   FOOTER
   ================================ */
.footer {
    background: var(--surface-color);
    border-top: 1px solid var(--border-color);
    padding: var(--spacing-2xl) 0 var(--spacing-lg);
    margin-top: auto;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

.footer-section h4 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

.footer-section p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: var(--spacing-xs);
}

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

.footer-links a:hover {
    color: var(--primary-color);
}

.social-links {
    display: flex;
    gap: var(--spacing-sm);
}

.social-btn {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: none;
    background: var(--background-color);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.social-btn:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-2px);
}

.footer-bottom {
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--border-color);
    text-align: center;
    color: var(--text-muted);
    font-size: var(--font-size-sm);
}

/* ================================
   TOAST NOTIFICATIONS
   ================================ */
.toast-container {
    position: fixed;
    top: var(--header-height);
    right: var(--spacing-md);
    z-index: 9999;
}

.toast {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
    box-shadow: var(--shadow-lg);
    min-width: 300px;
    animation: slideInRight var(--transition-normal) ease-out;
    position: relative;
}

.toast.success {
    border-left: 4px solid var(--success-color);
}

.toast.warning {
    border-left: 4px solid var(--warning-color);
}

.toast.error {
    border-left: 4px solid var(--error-color);
}

.toast.info {
    border-left: 4px solid var(--info-color);
}

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

/* ================================
   INSTALL PROMPT
   ================================ */
.install-prompt {
    position: fixed;
    bottom: var(--spacing-md);
    left: var(--spacing-md);
    right: var(--spacing-md);
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-xl);
    z-index: 9999;
    animation: slideInUp var(--transition-normal) ease-out;
}

.install-prompt.hidden {
    display: none;
}

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

.install-content i {
    font-size: var(--font-size-2xl);
    color: var(--primary-color);
}

.install-text {
    flex: 1;
}

.install-text h4 {
    margin-bottom: var(--spacing-xs);
}

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

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

/* ================================
   OVERLAY
   ================================ */
.overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 998;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
}

.overlay.active {
    opacity: 1;
    visibility: visible;
}

/* ================================
   UTILITY CLASSES
   ================================ */
.hidden {
    display: none !important;
}

.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;
}

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

.text-left {
    text-align: left;
}

.text-right {
    text-align: right;
}

.mt-auto {
    margin-top: auto;
}

.mb-auto {
    margin-bottom: auto;
}

/* ================================
   RESPONSIVE DESIGN
   ================================ */
@media (max-width: 1024px) {
    :root {
        --sidebar-width: 250px;
    }
    
    .search-container {
        display: block;
    }
    
    .search-container input {
        width: 200px;
    }
}

@media (max-width: 768px) {
    .header-content {
        padding: 0 var(--spacing-sm);
    }
    
    .tagline {
        display: none;
    }
    
    .search-container {
        display: none;
    }
    
    .menu-toggle {
        display: flex;
    }
    
    .sidebar {
        transform: translateX(-100%);
    }
    
    .sidebar.open {
        transform: translateX(0);
    }
    
    .main-content {
        margin-left: 0;
        padding-bottom: calc(var(--bottom-nav-height) + var(--spacing-xl));
    }
    
    .bottom-nav {
        display: flex;
    }
    
    .calculator-container {
        margin: var(--spacing-md);
        padding: var(--spacing-lg);
    }
    
    .calculator-title {
        font-size: var(--font-size-2xl);
    }
    
    .calc-buttons {
        gap: var(--spacing-xs);
    }
    
    .calc-btn {
        padding: var(--spacing-md);
        font-size: var(--font-size-lg);
        min-height: 50px;
    }
    
    .history-panel {
        width: 100%;
        right: -100%;
    }
    
    .footer-content {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-lg);
    }
    
    .install-prompt {
        bottom: calc(var(--bottom-nav-height) + var(--spacing-md));
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .calculator-container {
        margin: var(--spacing-sm);
        padding: var(--spacing-md);
    }
    
    .grid-2 {
        grid-template-columns: 1fr;
    }
    
    .grid-3 {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .grid-4 {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .calc-buttons {
        grid-template-columns: repeat(4, 1fr);
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    .install-content {
        flex-direction: column;
        text-align: center;
    }
    
    .chart-container {
        height: 300px;
    }
}

/* ================================
   PRINT STYLES
   ================================ */
@media print {
    .header,
    .sidebar,
    .bottom-nav,
    .footer,
    .history-panel,
    .install-prompt,
    .toast-container {
        display: none !important;
    }
    
    .main-content {
        margin-left: 0;
    }
    
    .calculator-container {
        box-shadow: none;
        border: 1px solid #ccc;
    }
    
    body {
        font-size: 12pt;
        line-height: 1.4;
    }
}

/* ================================
   HIGH CONTRAST MODE
   ================================ */
@media (prefers-contrast: high) {
    :root {
        --border-color: #000;
        --text-secondary: #000;
    }
    
    .btn {
        border: 2px solid currentColor;
    }
}

/* ================================
   REDUCED MOTION
   ================================ */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* ================================
   CUSTOM SCROLLBAR
   ================================ */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--background-color);
}

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: var(--border-radius-sm);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
}