/* CSS Variables for Theme Management */
:root {
    /* Light Theme Colors */
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-color: #64748b;
    --accent-color: #f59e0b;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    
    /* Background Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    --bg-modal: rgba(0, 0, 0, 0.5);
    
    /* Text Colors */
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    --text-inverse: #ffffff;
    
    /* Border Colors */
    --border-color: #e2e8f0;
    --border-focus: #2563eb;
    
    /* Shadow */
    --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);
    
    /* 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;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Border Radius */
    --border-radius-sm: 0.375rem;
    --border-radius-md: 0.5rem;
    --border-radius-lg: 0.75rem;
    --border-radius-xl: 1rem;
}

/* Dark Theme */
[data-theme="dark"] {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --bg-modal: rgba(0, 0, 0, 0.8);
    
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;
    
    --border-color: #334155;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    overflow-x: hidden;
    transition: all 0.3s ease;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* Header Styles */
.header {
    background: var(--bg-primary);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    transition: all 0.3s ease;
}

.navbar {
    padding: var(--spacing-md) 0;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.nav-brand {
    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;
    transition: all 0.3s ease;
}

.nav-brand:hover {
    transform: scale(1.02);
    opacity: 0.9;
}

/* Logo Styles */
.logo {
    height: 40px;
    width: auto;
    max-width: 160px;
    transition: all 0.3s ease;
    color: var(--text-primary);
}

/* Dark theme logo adjustments */
[data-theme="dark"] .logo {
    filter: brightness(1.1);
}

/* Responsive logo sizing */
@media (max-width: 768px) {
    .logo {
        height: 32px;
        max-width: 120px;
    }
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: var(--spacing-xl);
}

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--border-radius-md);
    transition: all 0.3s ease;
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary-color);
    background-color: var(--bg-tertiary);
}

.theme-toggle {
    background: var(--bg-tertiary);
    border: none;
    padding: var(--spacing-sm);
    border-radius: var(--border-radius-md);
    color: var(--text-primary);
    cursor: pointer;
    transition: all 0.3s ease;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-toggle:hover {
    background-color: var(--primary-color);
    color: var(--text-inverse);
    transform: scale(1.05);
}


/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-hover) 100%);
    color: var(--text-inverse);
    padding: 120px 0 80px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg width="60" height="60" viewBox="0 0 60 60" xmlns="http://www.w3.org/2000/svg"><g fill="none" fill-rule="evenodd"><g fill="%23ffffff" fill-opacity="0.1"><circle cx="30" cy="30" r="4"/></g></svg>');
    opacity: 0.1;
}

.hero-content {
    position: relative;
    z-index: 2;
}

.hero h1 {
    font-size: var(--font-size-4xl);
    font-weight: 800;
    margin-bottom: var(--spacing-lg);
    line-height: 1.2;
}

.hero p {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-2xl);
    opacity: 0.9;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.cta-button {
    display: inline-block;
    background: var(--text-inverse);
    color: var(--primary-color);
    padding: var(--spacing-md) var(--spacing-2xl);
    text-decoration: none;
    border-radius: var(--border-radius-lg);
    font-weight: 600;
    font-size: var(--font-size-lg);
    transition: all 0.3s ease;
    transform: translateY(0);
}

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

/* Ad Banner */
.ad-banner {
    background: var(--bg-secondary);
    padding: var(--spacing-lg) 0;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
}

/* Tools Section */
.tools-section {
    padding: var(--spacing-2xl) 0;
    background: var(--bg-primary);
}

.tools-section h2 {
    text-align: center;
    font-size: var(--font-size-3xl);
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
}

.section-description {
    text-align: center;
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-2xl);
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
    line-height: 1.6;
}

.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-2xl);
}

.tool-card {
    background: var(--bg-secondary);
    padding: var(--spacing-2xl);
    border-radius: var(--border-radius-xl);
    text-align: center;
    transition: all 0.3s ease;
    cursor: pointer;
    border: 1px solid var(--border-color);
    position: relative;
    overflow: hidden;
}

.tool-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(37, 99, 235, 0.1), transparent);
    transition: left 0.5s ease;
}

.tool-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.tool-card:hover::before {
    left: 100%;
}

.tool-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto var(--spacing-lg);
    transition: all 0.3s ease;
}

.tool-card:hover .tool-icon {
    transform: scale(1.1) rotate(5deg);
}

.tool-icon i {
    font-size: var(--font-size-2xl);
    color: var(--text-inverse);
}

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

.tool-card p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Modal Styles */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--bg-modal);
    z-index: 2000;
    backdrop-filter: blur(5px);
}

.modal-content {
    background: var(--bg-primary);
    margin: 2% auto;
    padding: 0;
    border-radius: var(--border-radius-xl);
    width: 90%;
    max-width: 800px;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
    animation: modalSlideIn 0.3s ease;
}

@keyframes modalSlideIn {
    from { transform: translateY(-50px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

.close {
    position: absolute;
    top: var(--spacing-lg);
    right: var(--spacing-lg);
    font-size: var(--font-size-2xl);
    font-weight: bold;
    color: var(--text-secondary);
    cursor: pointer;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    transition: all 0.3s ease;
    z-index: 10;
}

.close:hover {
    background-color: var(--danger-color);
    color: var(--text-inverse);
}

/* Calculator Templates */
.calculator-template {
    display: none;
}

#calculatorContent .calculator-template {
    display: block;
    padding: var(--spacing-2xl);
}

#calculatorContent h2 {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    font-size: var(--font-size-2xl);
    font-weight: 700;
    margin-bottom: var(--spacing-2xl);
    color: var(--text-primary);
    border-bottom: 2px solid var(--primary-color);
    padding-bottom: var(--spacing-md);
}

#calculatorContent h2 i {
    color: var(--primary-color);
}

.calculator-form {
    margin-bottom: var(--spacing-2xl);
}

.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-group label {
    display: block;
    margin-bottom: var(--spacing-sm);
    font-weight: 600;
    color: var(--text-primary);
    font-size: var(--font-size-sm);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.form-group input,
.form-group select {
    width: 100%;
    padding: var(--spacing-md);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-base);
    transition: all 0.3s ease;
    background: var(--bg-primary);
    color: var(--text-primary);
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
    transform: translateY(-1px);
}

.calculate-btn {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
    color: var(--text-inverse);
    border: none;
    padding: var(--spacing-md) var(--spacing-2xl);
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-lg);
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    width: 100%;
    margin-top: var(--spacing-lg);
    position: relative;
    overflow: hidden;
}

.calculate-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 ease;
}

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

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

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

/* Result Section */
.result-section {
    margin-top: var(--spacing-2xl);
    padding: var(--spacing-xl);
    background: var(--bg-secondary);
    border-radius: var(--border-radius-lg);
    border-left: 4px solid var(--primary-color);
}

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

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

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

.highlight {
    background: linear-gradient(135deg, var(--success-color), #059669);
    color: var(--text-inverse);
    padding: var(--spacing-lg);
    border-radius: var(--border-radius-md);
    text-align: center;
    margin-top: var(--spacing-md);
}

/* Inline Ads */
.inline-ad {
    margin: var(--spacing-2xl) 0;
    padding: var(--spacing-lg);
    background: var(--bg-tertiary);
    border-radius: var(--border-radius-md);
    text-align: center;
}

/* Footer Ad */
.footer-ad {
    margin-top: var(--spacing-2xl);
    margin-bottom: 0;
}

/* Progress Bar for Savings Tracker */
.progress-container {
    background: var(--bg-tertiary);
    border-radius: var(--border-radius-lg);
    padding: 4px;
    margin: var(--spacing-md) 0;
    overflow: hidden;
}

.progress-bar {
    height: 20px;
    background: linear-gradient(135deg, var(--success-color), #059669);
    border-radius: var(--border-radius-md);
    transition: width 0.5s ease;
    position: relative;
    overflow: hidden;
}

.progress-bar::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    background-image: linear-gradient(
        45deg,
        rgba(255, 255, 255, 0.2) 25%,
        transparent 25%,
        transparent 50%,
        rgba(255, 255, 255, 0.2) 50%,
        rgba(255, 255, 255, 0.2) 75%,
        transparent 75%,
        transparent
    );
    background-size: 20px 20px;
    animation: progress-animation 1s linear infinite;
}

@keyframes progress-animation {
    0% { background-position: 0 0; }
    100% { background-position: 20px 0; }
}

/* Footer */
.footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    padding: var(--spacing-2xl) 0 var(--spacing-lg);
}

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

.footer-section h3,
.footer-section h4 {
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.footer-section h3 {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-xl);
    color: var(--primary-color);
}

.footer-section p {
    color: var(--text-secondary);
    line-height: 1.6;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: var(--spacing-sm);
}

.footer-section ul li a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-section ul li a:hover {
    color: var(--primary-color);
}

.social-links {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.social-links a {
    width: 40px;
    height: 40px;
    background: var(--bg-tertiary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-secondary);
    text-decoration: none;
    transition: all 0.3s ease;
}

.social-links a:hover {
    background: var(--primary-color);
    color: var(--text-inverse);
    transform: translateY(-2px);
}

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

/* Loading Animation */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(37, 99, 235, 0.3);
    border-radius: 50%;
    border-top-color: var(--primary-color);
    animation: spin 1s ease-in-out infinite;
}

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

/* Large Screen Optimization */
@media (min-width: 1400px) {
    .container {
        max-width: 1400px;
    }
    
    .tools-grid {
        grid-template-columns: repeat(3, 1fr);
        max-width: 1200px;
        margin: 0 auto;
    }
    
    .hero h1 {
        font-size: 3rem;
    }
    
    .hero p {
        font-size: var(--font-size-2xl);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 0 var(--spacing-md);
    }
    
    .nav-container {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
    
    .nav-menu {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
        gap: var(--spacing-sm);
        width: 100%;
    }
    
    .nav-link {
        font-size: var(--font-size-sm);
        padding: var(--spacing-xs) var(--spacing-sm);
    }
    
    .theme-toggle {
        width: 35px;
        height: 35px;
    }
    
    .header {
        padding: var(--spacing-xs) 0;
    }
    
    .navbar {
        padding: var(--spacing-sm) 0;
    }
    
    .hero {
        padding: 100px 0 60px;
    }
    
    .hero h1 {
        font-size: var(--font-size-3xl);
    }
    
    .hero p {
        font-size: var(--font-size-lg);
    }
    
    .tools-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }
    
    .modal-content {
        width: 95%;
        margin: 5% auto;
        max-height: 85vh;
    }
    
    #calculatorContent .calculator-template {
        padding: var(--spacing-lg);
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .social-links {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .nav-brand {
        font-size: var(--font-size-lg);
        gap: var(--spacing-xs);
    }
    
    .nav-brand i {
        font-size: var(--font-size-xl);
    }
    
    .nav-menu {
        gap: var(--spacing-xs);
    }
    
    .nav-link {
        font-size: var(--font-size-xs);
        padding: var(--spacing-xs);
    }
    
    .theme-toggle {
        width: 30px;
        height: 30px;
        font-size: var(--font-size-sm);
    }
    
    .hero {
        padding: 90px 0 50px;
    }
    
    .hero h1 {
        font-size: var(--font-size-2xl);
        line-height: 1.3;
    }
    
    .hero p {
        font-size: var(--font-size-base);
    }
    
    .cta-button {
        padding: var(--spacing-sm) var(--spacing-lg);
        font-size: var(--font-size-base);
    }
    
    .section-description {
        font-size: var(--font-size-base);
        padding: 0 var(--spacing-sm);
    }
    
    .tool-card {
        padding: var(--spacing-lg);
    }
    
    .tool-card h3 {
        font-size: var(--font-size-lg);
        line-height: 1.3;
    }
    
    .tool-card p {
        font-size: var(--font-size-sm);
        line-height: 1.4;
    }
    
    .tool-icon {
        width: 60px;
        height: 60px;
    }
    
    .tool-icon i {
        font-size: var(--font-size-xl);
    }
    
    #calculatorContent h2 {
        font-size: var(--font-size-xl);
        flex-direction: column;
        text-align: center;
        gap: var(--spacing-sm);
    }
    
    .footer-content {
        gap: var(--spacing-lg);
    }
    
    .footer-section h3,
    .footer-section h4 {
        font-size: var(--font-size-base);
    }
}

/* Print Styles */
@media print {
    .header,
    .footer,
    .ad-banner,
    .inline-ad,
    .theme-toggle,
    .close {
        display: none;
    }
    
    .modal-content {
        box-shadow: none;
        border: 1px solid #000;
    }
    
    * {
        color: #000 !important;
        background: #fff !important;
    }
}

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

/* High contrast mode */
@media (prefers-contrast: high) {
    :root {
        --border-color: #000;
        --text-secondary: #000;
    }
}

/* Focus styles for better accessibility */
input:focus,
button:focus,
select:focus,
.nav-link:focus,
.tool-card:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* Scientific Calculator Styles */
.calculator-display {
    margin-bottom: var(--spacing-lg);
    background: var(--bg-tertiary);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: var(--spacing-sm);
}

.display-history {
    min-height: 20px;
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    text-align: right;
    padding: var(--spacing-xs) var(--spacing-sm);
    font-family: 'Courier New', monospace;
}

#calculatorDisplay {
    width: 100%;
    padding: var(--spacing-md) var(--spacing-sm);
    font-size: var(--font-size-2xl);
    text-align: right;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-weight: 600;
    font-family: 'Courier New', monospace;
    outline: none;
}

.calculator-modes {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
    padding: var(--spacing-sm);
    background: var(--bg-secondary);
    border-radius: var(--border-radius-md);
}

.mode-btn {
    padding: var(--spacing-xs) var(--spacing-md);
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: var(--font-size-sm);
}

.mode-btn.active {
    background: var(--primary-color);
    color: var(--text-inverse);
    border-color: var(--primary-color);
}

.mode-btn:hover {
    transform: translateY(-1px);
}

.mode-indicator {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    font-weight: 600;
}

.calculator-buttons {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.button-row {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-xs);
}

.button-row.scientific {
    grid-template-columns: repeat(5, 1fr);
}

.button-row:last-child {
    grid-template-columns: 2fr 1fr 1fr;
}

.calc-btn {
    padding: var(--spacing-md);
    font-size: var(--font-size-base);
    font-weight: 600;
    border: none;
    border-radius: var(--border-radius-sm);
    cursor: pointer;
    transition: all 0.2s ease;
    min-height: 45px;
    display: flex;
    align-items: center;
    justify-content: center;
}

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

.calc-btn.number:hover {
    background: var(--bg-tertiary);
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
}

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

.calc-btn.operator:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.calc-btn.function {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: var(--text-inverse);
    font-size: var(--font-size-sm);
}

.calc-btn.function:hover {
    background: linear-gradient(135deg, #5a67d8 0%, #6b46c1 100%);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.calc-btn.memory {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    color: var(--text-inverse);
    font-size: var(--font-size-sm);
}

.calc-btn.memory:hover {
    background: linear-gradient(135deg, #ec4899 0%, #ef4444 100%);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.calc-btn.clear {
    background: var(--warning-color);
    color: var(--text-inverse);
}

.calc-btn.clear:hover {
    background: #f59e0b;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.calc-btn.equals {
    background: var(--success-color);
    color: var(--text-inverse);
    font-size: var(--font-size-xl);
}

.calc-btn.equals:hover {
    background: #059669;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.calc-btn:active {
    transform: scale(0.98);
}

.calc-btn.zero {
    grid-column: span 1;
}

/* Memory indicator */
.memory-indicator {
    position: absolute;
    top: 2px;
    right: 2px;
    width: 6px;
    height: 6px;
    background: var(--success-color);
    border-radius: 50%;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.memory-indicator.active {
    opacity: 1;
}

/* Calculator responsive design */
@media (max-width: 768px) {
    .button-row.scientific {
        grid-template-columns: repeat(5, 1fr);
    }
    
    .calc-btn {
        padding: var(--spacing-sm);
        font-size: var(--font-size-sm);
        min-height: 40px;
    }
    
    .calc-btn.function,
    .calc-btn.memory {
        font-size: var(--font-size-xs);
    }
    
    #calculatorDisplay {
        font-size: var(--font-size-xl);
        padding: var(--spacing-sm);
    }
    
    .display-history {
        font-size: var(--font-size-xs);
    }
}

@media (max-width: 480px) {
    .calc-btn {
        padding: var(--spacing-xs);
        font-size: var(--font-size-xs);
        min-height: 35px;
    }
    
    .calc-btn.equals {
        font-size: var(--font-size-lg);
    }
    
    #calculatorDisplay {
        font-size: var(--font-size-lg);
    }
    
    .calculator-modes {
        padding: var(--spacing-xs);
    }
    
    .mode-btn {
        padding: var(--spacing-xs);
        font-size: var(--font-size-xs);
    }
}

/* Smooth scrolling for Safari */
@supports (scroll-behavior: smooth) {
    html {
        scroll-behavior: smooth;
    }
}