/* ===== CSS Variables ===== */
:root {
    --primary-color: #3498db;
    --primary-dark: #2980b9;
    --primary-light: #5dade2;
    --secondary-color: #2ecc71;
    --accent-color: #9b59b6;
    --dark-color: #2c3e50;
    --light-color: #ecf0f1;
    --gray-color: #95a5a6;
    --gray-light: #bdc3c7;
    --white: #ffffff;
    --black: #000000;
    --border-color: #e0e0e0;
    --bg-color: #f8f9fa;
    --card-bg: #ffffff;
    --text-color: #2c3e50;
    --text-muted: #6c757d;
    --success-color: #28a745;
    --error-color: #dc3545;
    --warning-color: #ffc107;
    --info-color: #17a2b8;

    /* Effects */
    --box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --box-shadow-hover: 0 4px 20px rgba(0, 0, 0, 0.15);
    --transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    --border-radius: 8px;
    --border-radius-lg: 12px;
    --border-radius-xl: 16px;

    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-base: 16px;
    --font-size-sm: 14px;
    --font-size-lg: 18px;
    --font-size-xl: 20px;
    --font-size-2xl: 24px;
    --font-size-3xl: 32px;
    --font-size-4xl: 40px;
    --line-height: 1.6;
    --font-weight-light: 300;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;

    /* Spacing */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    --spacing-2xl: 48px;
    --spacing-3xl: 64px;

    /* Layout */
    --container-max-width: 1200px;
    --navbar-height: 70px;
    --header-height: 200px;
}

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

html {
    font-size: var(--font-size-base);
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    line-height: var(--line-height);
    color: var(--text-color);
    font-weight: var(--font-weight-normal);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    /* Prevent accidental horizontal scrolling that can reveal off-canvas elements */
    overflow-x: hidden;
}

/* ===== Layout Components ===== */
.container {
    width: 100%;
    padding: 0 var(--spacing-lg);
}

/* ===== Header ===== */
.header {
    padding: var(--spacing-3xl) 0;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    opacity: 0.3;
}

.header-content {
    position: relative;
    z-index: 1;
}

.header-title {
    font-size: var(--font-size-4xl);
    font-weight: var(--font-weight-bold);
    margin-bottom: var(--spacing-md);
}

.header-subtitle {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-light);
    opacity: 0.9;
    max-width: 800px;
    margin: 0 auto;
}

/* ===== Navigation ===== */
.navbar {
    background-color: var(--white);
    box-shadow: var(--box-shadow);
    position: sticky;
    top: 0;
    z-index: 2000;
    /* keep above menu/backdrop */
    transition: var(--transition);
}

.navbar .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 var(--spacing-lg);
    height: var(--navbar-height);
}

.nav-brand .brand-link {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: var(--dark-color);
    font-weight: var(--font-weight-semibold);
    font-size: var(--font-size-lg);
    transition: var(--transition);
}

.nav-brand .brand-link:hover {
    color: var(--primary-color);
    transform: translateY(-1px);
}

.nav-brand .brand-link i {
    margin-right: var(--spacing-sm);
    font-size: var(--font-size-xl);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: space-around;
    width: 40px;
    height: 40px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 8px;
    z-index: 3001;
    /* above full-screen menu */
    position: relative;
    -webkit-tap-highlight-color: transparent;
    /* Allow clicks and taps to register reliably on Android */
    touch-action: manipulation;
    -ms-touch-action: manipulation;
}

.hamburger-line {
    width: 24px;
    height: 3px;
    background-color: var(--dark-color);
    border-radius: 2px;
    transition: all 0.3s ease;
    transform-origin: center;
    display: block;
    margin: 2px 0;
}

.nav-toggle.active .hamburger-line:nth-child(1) {
    transform: rotate(45deg) translate(6px, 6px);
}

.nav-toggle.active .hamburger-line:nth-child(2) {
    opacity: 0;
}

.nav-toggle.active .hamburger-line:nth-child(3) {
    transform: rotate(-45deg) translate(6px, -6px);
}

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

/* Navbar date display */
.nav-date {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-left: var(--spacing-md);
    text-decoration: none;
    cursor: pointer;
    /* make date area a little taller and clickable without touching nav links */
    padding: 6px 8px;
    border-radius: 10px;
}

.nav-date:hover {
    background-color: rgba(52, 152, 219, 0.04);
}

.nav-date-ad {
    font-weight: var(--font-weight-semibold);
    color: var(--white);
    background-color: var(--primary-color);
    padding: 6px 10px;
    border-radius: 999px;
    box-shadow: var(--box-shadow);
    display: inline-block;
    font-size: 0.95rem;
}

.nav-date-bs {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 6px;
    line-height: 1;
    transform: translateY(-2px);
}

/* Mobile menu date area (when menu expands) */
.nav-date-mobile {
    padding: var(--spacing-md) 0;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: var(--spacing-md);
    text-align: left;
}

.nav-date-mobile .nav-date-ad {
    background-color: var(--primary-light);
    color: var(--white);
    padding: 8px 12px;
    border-radius: var(--border-radius);
    display: inline-block;
    box-shadow: none;
}

.nav-date-mobile .nav-date-bs {
    display: block;
    margin-top: 8px;
    color: var(--text-muted);
}

.nav-link {
    display: flex;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--text-color);
    text-decoration: none;
    border-radius: var(--border-radius);
    transition: var(--transition);
    font-weight: var(--font-weight-medium);
    position: relative;
}

.nav-link:hover {
    background-color: rgba(52, 152, 219, 0.1);
    color: var(--primary-color);
    transform: translateY(-2px);
}

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

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

.nav-link i {
    margin-right: var(--spacing-xs);
    font-size: var(--font-size-sm);
}

/* ===== Main Content ===== */
.main-content {
    padding: var(--spacing-2xl) 0;
    min-height: calc(100vh - 500px);
}

/* ===== Cards ===== */
.card {
    background-color: var(--card-bg);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

/* Styles for nepalidate template */
.date-card {
    text-align: center;
    padding: 24px;
}

.date-title {
    font-size: var(--font-size-lg);
    color: var(--primary-dark);
    margin: 8px 0 4px;
}

.date-value {
    font-size: 1.25rem;
    margin: 8px 0 12px;
    color: var(--text-color);
    font-weight: var(--font-weight-medium);
}

.muted {
    color: var(--text-muted);
    margin-top: 12px;
}


.card-header {
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-lg);
    border-bottom: 2px solid var(--border-color);
}

.card-title {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-semibold);
    color: var(--primary-dark);
    margin-bottom: var(--spacing-sm);
}

.card-subtitle {
    color: var(--text-muted);
    font-size: var(--font-size-base);
}

/* ===== Typography ===== */
h1,
h2,
h3,
h4,
h5,
h6 {
    font-weight: var(--font-weight-semibold);
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
}

h1 {
    font-size: var(--font-size-4xl);
}

h2 {
    font-size: var(--font-size-3xl);
    color: var(--primary-dark);
}

h3 {
    font-size: var(--font-size-2xl);
    color: var(--accent-color);
}

h4 {
    font-size: var(--font-size-xl);
}

h5 {
    font-size: var(--font-size-lg);
}

h6 {
    font-size: var(--font-size-base);
}

p {
    margin-bottom: var(--spacing-md);
    color: var(--text-color);
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    color: var(--primary-dark);
}

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

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

.form-control {
    width: 100%;
    padding: var(--spacing-md);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: var(--font-size-base);
    font-family: var(--font-family);
    transition: var(--transition);
    background-color: var(--white);
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.1);
}

.form-control::placeholder {
    color: var(--text-muted);
    opacity: 1;
}

select.form-control {
    cursor: pointer;
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    font-family: var(--font-family);
    text-decoration: none;
    border-radius: var(--border-radius);
    border: none;
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
    line-height: 1;
    user-select: none;
    position: relative;
    overflow: hidden;
}

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

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: var(--white);
    box-shadow: 0 4px 15px rgba(52, 152, 219, 0.3);
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--primary-dark), var(--primary-color));
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(52, 152, 219, 0.4);
    color: var(--white);
    text-decoration: none;
}

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

.btn-secondary:hover {
    background-color: var(--dark-color);
    color: var(--white);
    text-decoration: none;
}

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

.btn-success:hover {
    background-color: #218838;
    color: var(--white);
    text-decoration: none;
}

.btn-lg {
    padding: var(--spacing-lg) var(--spacing-2xl);
    font-size: var(--font-size-lg);
}

.btn-sm {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-sm);
}

/* Ripple effect element - absolutely positioned so it doesn't affect layout */
.ripple {
    position: absolute;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.35);
    transform: scale(0);
    opacity: 0.9;
    pointer-events: none;
    animation: ripple-effect 0.6s ease-out forwards;
    will-change: transform, opacity;
}

@keyframes ripple-effect {
    to {
        transform: scale(2.5);
        opacity: 0;
    }
}

/* ===== Alerts & Messages ===== */
.alert {
    padding: var(--spacing-md);
    border-radius: var(--border-radius);
    border: 1px solid transparent;
    margin-bottom: var(--spacing-lg);
}

.alert-success {
    color: #155724;
    background-color: #d4edda;
    border-color: #c3e6cb;
}

.alert-error {
    color: #721c24;
    background-color: #f8d7da;
    border-color: #f5c6cb;
}

.alert-info {
    color: #0c5460;
    background-color: #d1ecf1;
    border-color: #bee5eb;
}

.alert-warning {
    color: #856404;
    background-color: #fff3cd;
    border-color: #ffeaa7;
}

/* ===== Result Display ===== */
.result-display {
    font-weight: var(--font-weight-semibold);
    padding: var(--spacing-lg);
    margin-top: var(--spacing-lg);
    border-radius: var(--border-radius);
    font-size: var(--font-size-2xl);
    text-align: center;
    transition: var(--transition);
    animation: slideIn 0.3s ease-out;
}

.result-success {
    color: var(--success-color);
    background: linear-gradient(135deg, #d4edda, #c3e6cb);
    border: 2px solid var(--success-color);
}

.result-error {
    color: var(--error-color);
    background: linear-gradient(135deg, #f8d7da, #f5c6cb);
    border: 2px solid var(--error-color);
}

/* ===== Date Converter Specific Styles ===== */
.converter-section {
    background-color: var(--white);
    border-radius: var(--border-radius-xl);
    box-shadow: var(--box-shadow);
    padding: var(--spacing-2xl);
    margin: var(--spacing-xl) 0;
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.converter-section:hover {
    box-shadow: var(--box-shadow-hover);
}

.section-title {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    color: var(--primary-dark);
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-semibold);
}

.conversion-type-selector {
    background: linear-gradient(135deg, var(--bg-color), var(--white));
    border: 2px solid var(--border-color);
    font-weight: var(--font-weight-medium);
    color: var(--text-color);
    cursor: pointer;
}

.conversion-type-selector:hover {
    border-color: var(--primary-color);
    background: var(--white);
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.form-row .form-control {
    margin-bottom: 0;
}

/* ===== Code Blocks ===== */
pre {
    background-color: #2d3748;
    color: #e2e8f0;
    padding: var(--spacing-lg);
    border-radius: var(--border-radius);
    overflow-x: auto;
    font-family: 'Fira Code', 'Courier New', monospace;
    line-height: 1.5;
    margin-bottom: var(--spacing-lg);
    border: 1px solid #4a5568;
}

code {
    background-color: #f7fafc;
    color: #2d3748;
    padding: 2px 6px;
    border-radius: 4px;
    font-family: 'Fira Code', 'Courier New', monospace;
    font-size: 0.9em;
    border: 1px solid var(--border-color);
}

pre code {
    background: none;
    color: inherit;
    padding: 0;
    border: none;
}

/* ===== API Documentation Styles ===== */
.endpoint {
    margin-bottom: var(--spacing-2xl);
    border-left: 4px solid var(--primary-color);
    padding-left: var(--spacing-lg);
}

.endpoint-method {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--border-radius);
    font-weight: var(--font-weight-bold);
    font-size: var(--font-size-sm);
    text-transform: uppercase;
    margin-right: var(--spacing-md);
}

.method-get {
    background-color: #61affe;
    color: var(--white);
}

.method-post {
    background-color: #49cc90;
    color: var(--white);
}

.method-put {
    background-color: #fca130;
    color: var(--white);
}

.method-delete {
    background-color: #f93e3e;
    color: var(--white);
}

.example-request,
.example-response {
    background-color: #f8f9fa;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: var(--spacing-lg);
    margin: var(--spacing-md) 0;
}

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

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

/* ===== About Page (About.html) ===== */
.overview-content .lead {
    font-size: 1.1rem;
    line-height: 1.7;
    color: var(--text-muted);
    margin-bottom: var(--spacing-xl);
}

.project-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
}

.stat-item {
    text-align: center;
    padding: var(--spacing-lg);
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: var(--white);
    border-radius: var(--border-radius-lg);
}

.stat-number {
    font-size: 2rem;
    font-weight: var(--font-weight-bold);
    margin-bottom: var(--spacing-xs);
}

.stat-label {
    font-size: var(--font-size-sm);
    opacity: 0.9;
}

.developer-profile {
    display: grid;
    grid-template-columns: 150px 1fr;
    gap: var(--spacing-2xl);
    align-items: start;
}

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

.avatar-placeholder {
    width: 120px;
    height: 120px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 3rem;
    color: var(--white);
    margin: 0 auto var(--spacing-md);
}

.developer-details h3 {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-xs);
    color: var(--primary-dark);
}

.developer-title {
    color: var(--text-muted);
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-lg);
    font-weight: var(--font-weight-medium);
}

.developer-description {
    margin-bottom: var(--spacing-xl);
}

.developer-links {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.contact-methods {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
    margin: var(--spacing-2xl) 0;
}

.contact-method {
    text-align: center;
    padding: var(--spacing-xl);
    background: var(--bg-color);
    border-radius: var(--border-radius-lg);
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.contact-method:hover {
    transform: translateY(-4px);
    box-shadow: var(--box-shadow-hover);
}

.contact-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--accent-color), #8e44ad);
    color: var(--white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    margin: 0 auto var(--spacing-md);
}

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

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

.section-title {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
}

.nav-date-mobile {
    display: none;
}

@media (max-width: 768px) {

    /* Hide the desktop nav date on small screens; mobile menu will show date */
    .nav-date {
        display: none;
    }

    .nav-date-mobile {
        display: flex;
        flex-direction: column;
        align-items: flex-start;
        padding: var(--spacing-md) var(--spacing-lg);
        border-bottom: 1px solid var(--border-color);
        font-size: 0.95rem;
        color: var(--text-muted);
    }

    .project-stats {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-md);
    }

    .developer-profile {
        grid-template-columns: 1fr;
        text-align: center;
        gap: var(--spacing-lg);
    }

    .developer-links {
        justify-content: center;
    }

    .contact-methods {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }
}

@media (max-width: 480px) {
    .project-stats {
        grid-template-columns: 1fr;
    }

    .developer-links {
        flex-direction: column;
        align-items: center;
    }

    .developer-links .btn {
        width: 100%;
        max-width: 250px;
    }
}

/* ===== Footer ===== */
.footer {
    background-color: #1a1f2e;
    color: #e0e4eb;
    padding: var(--spacing-2xl) 0 0;
    margin-top: var(--spacing-3xl);
    position: relative;
    overflow: hidden;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
    padding: var(--spacing-xl) 0;
    margin: 0 auto;
    max-width: 1200px;
}

.footer-section h3 {
    color: #fff;
    margin-bottom: var(--spacing-md);
    font-size: 1.25rem;
    font-weight: 600;
    position: relative;
    padding-bottom: 10px;
}

.footer-section h3::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: 0;
    width: 40px;
    height: 2px;
    background: var(--primary-color);
}

.footer-section p {
    margin-bottom: var(--spacing-md);
    opacity: 0.8;
    line-height: 1.7;
    font-size: 0.95rem;
    color: #b0b8c5;
}

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

.footer-links a {
    display: inline-flex;
    align-items: center;
    color: #b0b8c5;
    margin-bottom: 12px;
    text-decoration: none;
    transition: all 0.3s ease;
    font-size: 0.95rem;
    padding: 6px 0;
}

.footer-links a:hover {
    color: var(--primary-color);
    transform: translateX(5px);
}

.footer-links a::before {
    content: '→';
    margin-right: 8px;
    opacity: 0;
    transition: all 0.3s ease;
    color: var(--primary-color);
}

.footer-links a:hover::before {
    opacity: 1;
    margin-right: 12px;
}

.social-links {
    display: flex;
    gap: 12px;
    margin-top: var(--spacing-md);
}

.social-links a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: rgba(255, 255, 255, 0.05);
    color: #b0b8c5;
    border-radius: 50%;
    font-size: 1.1rem;
    transition: all 0.3s ease;
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.social-links a:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
}

.footer-bottom {
    text-align: center;
    padding: var(--spacing-lg) 0;
    margin-top: var(--spacing-xl);
    font-size: 0.9rem;
    color: #8a94a6;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.footer-bottom p {
    margin: 0;
    font-size: 0.9rem;
    color: #8a94a6;
}

.footer-bottom a {
    color: var(--primary-light);
    text-decoration: none;
}

/* ===== Responsive Design ===== */
@media (max-width: 1024px) {

    /* Footer */
    .footer {
        text-align: left;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }

    .footer-section {
        margin-bottom: 0;
    }

    .footer-links a {
        display: inline-flex;
        margin-right: 15px;
    }

    .social-links {
        justify-content: flex-start;
    }
}

@media (max-width: 992px) {
    .footer-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }

    .home-hero h1 {
        font-size: 1.8rem;
    }

    .home-hero p {
        font-size: 1.05rem;
    }

    .header-subtitle {
        font-size: 1.1rem;
    }
}

@media (max-width: 768px) {

    /* Header */
    .header {
        padding: var(--spacing-2xl) 0;
    }

    .header-title {
        font-size: var(--font-size-3xl);
    }

    .header-subtitle {
        font-size: var(--font-size-base);
    }

    /* Navigation */
    .nav-toggle {
        display: flex;
    }

    /* Use absolute offset (right) to hide the menu instead of translateX so closed menu doesn't
       create horizontal overflow that can be scrolled into view on some mobile browsers. Keep
       transform as fallback for older browsers but prefer right for layout stability. */
    .nav-menu {
        position: fixed;
        top: 0;
        /* hide off-canvas by moving fully to the right */
        right: -100%;
        width: 100vw;
        /* full width */
        height: 100dvh;
        /* full height */
        background-color: var(--white);
        box-shadow: none;
        transition: right 0.3s ease, transform 0.3s ease;
        z-index: 3000;
        /* above navbar/backdrop */
        overflow-y: auto;
        border-left: none;
        padding-top: calc(env(safe-area-inset-top, 0) + var(--spacing-lg));
        padding-bottom: calc(env(safe-area-inset-bottom, 0) + var(--spacing-lg));
        -webkit-overflow-scrolling: touch;
        /* smooth scroll inside menu */
        will-change: right, transform;
        contain: layout paint;
        /* fallback transform value for browsers that still use it */
        transform: translateX(0);
    }

    .nav-menu.active {
        right: 0;
        transform: translateX(0);
    }

    /* Mobile menu backdrop */

    .nav-backdrop {
        position: fixed;
        top: 0;
        left: 0;
        /* use viewport width to cover even if body/html overflow differs */
        width: 100vw;
        height: 100dvh;
        background-color: rgba(0, 0, 0, 0.5);
        z-index: 2000;
        opacity: 0;
        visibility: hidden;
        transition: opacity 0.3s ease, visibility 0.3s ease;
        -webkit-tap-highlight-color: transparent;
        touch-action: manipulation;
        -ms-touch-action: manipulation;
    }

    .nav-backdrop.active {
        opacity: 1;
        visibility: visible;
    }

    /* Prevent body scroll when menu is open */
    body.nav-open {
        /* prevent scroll while open; keep overflow-x hidden to avoid horizontal reveal */
        overflow: hidden;
        overflow-x: hidden;
    }

    .nav-links {
        flex-direction: column;
        padding: var(--spacing-2xl) var(--spacing-xl);
        /* room at top for status bar */
        gap: var(--spacing-xs);
    }

    .nav-link {
        width: 100%;
        padding: var(--spacing-md);
        justify-content: flex-start;
        border-radius: var(--border-radius);
        min-height: 48px;
        /* Better tap target */
    }

    /* Improve sticky header on Android with cutouts */
    .navbar {
        padding-top: 0;
        /* overlay menu sits above; avoid visible strip */
    }

    /* Cards */
    .card {
        padding: var(--spacing-lg);
        margin-bottom: var(--spacing-lg);
    }

    /* Forms */
    .form-row {
        grid-template-columns: 1fr;
        gap: var(--spacing-sm);
    }

    /* Typography */
    h1 {
        font-size: var(--font-size-3xl);
    }

    h2 {
        font-size: var(--font-size-2xl);
    }

    h3 {
        font-size: var(--font-size-xl);
    }

    /* Result display */
    .result-display {
        font-size: var(--font-size-xl);
        padding: var(--spacing-md);
    }

    /* Footer */
    .footer {
        padding: var(--spacing-xl) 0 var(--spacing-md);
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
        text-align: center;
    }

    .footer-links {
        align-items: center;
    }

    .social-links {
        justify-content: center;
    }

    .footer-section h3 {
        font-size: var(--font-size-base);
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }

    .header-title {
        font-size: var(--font-size-2xl);
    }

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

    .btn {
        width: 100%;
        justify-content: center;
    }

    .result-display {
        font-size: var(--font-size-lg);
    }

    pre {
        padding: var(--spacing-md);
        font-size: var(--font-size-sm);
    }
}

/* ===== Dark Mode Support ===== */
@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #1a202c;
        --card-bg: #2d3748;
        --text-color: #e2e8f0;
        --text-muted: #a0aec0;
        --border-color: #4a5568;
    }

    .navbar {
        background-color: var(--card-bg);
    }

    .form-control {
        background-color: var(--card-bg);
        color: var(--text-color);
        border-color: var(--border-color);
    }

    code {
        background-color: var(--card-bg);
        color: var(--text-color);
    }
}