/**
 * Day Countly - Modern Design System & Stylesheet
 * Responsive, accessible, light/dark mode with glassmorphic accents.
 */

:root {
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
    --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;

    /* Light Theme Palette */
    --bg-main: #f8fafc;
    --bg-surface: #ffffff;
    --bg-surface-elevated: #ffffff;
    --bg-surface-subtle: #f1f5f9;
    --border-color: #e2e8f0;
    --border-focus: #6366f1;

    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #64748b;
    --text-inverse: #ffffff;

    --primary: #4f46e5;
    --primary-hover: #4338ca;
    --primary-light: #eef2ff;
    --primary-text: #4f46e5;

    --accent: #06b6d4;
    --success: #10b981;
    --success-bg: #ecfdf5;
    --warning: #f59e0b;
    --warning-bg: #fffbeb;
    --error: #ef4444;
    --error-bg: #fef2f2;

    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.08), 0 2px 4px -2px rgb(0 0 0 / 0.05);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.08), 0 4px 6px -4px rgb(0 0 0 / 0.05);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-full: 9999px;

    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
    --bg-main: #0b0f19;
    --bg-surface: #111827;
    --bg-surface-elevated: #1e293b;
    --bg-surface-subtle: #1e293b;
    --border-color: #334155;
    --border-focus: #818cf8;

    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;
    --text-inverse: #0f172a;

    --primary: #6366f1;
    --primary-hover: #818cf8;
    --primary-light: rgba(99, 102, 241, 0.15);
    --primary-text: #a5b4fc;

    --accent: #22d3ee;
    --success: #34d399;
    --success-bg: rgba(16, 185, 129, 0.15);
    --warning: #fbbf24;
    --warning-bg: rgba(245, 158, 11, 0.15);
    --error: #f87171;
    --error-bg: rgba(239, 68, 68, 0.15);

    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.5);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.4);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.5);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.6);
}

/* Reset & Base */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
    overflow-x: hidden;
    overflow-x: clip;
    width: 100%;
    max-width: 100vw;
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-main);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    transition: background-color 0.25s ease, color 0.25s ease;
    overflow-x: hidden;
    overflow-x: clip;
    width: 100%;
    max-width: 100vw;
    position: relative;
}

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

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

img, svg {
    max-width: 100%;
    height: auto;
    vertical-align: middle;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    color: var(--text-primary);
    font-weight: 700;
    line-height: 1.25;
    margin-bottom: 0.75rem;
}

h1 { font-size: 2.25rem; letter-spacing: -0.025em; }
h2 { font-size: 1.75rem; letter-spacing: -0.02em; margin-top: 2rem; }
h3 { font-size: 1.25rem; margin-top: 1.5rem; }
p { margin-bottom: 1rem; color: var(--text-secondary); }

/* Layout Container */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.25rem;
    box-sizing: border-box;
}

.main-content {
    flex: 1 0 auto;
    padding-bottom: 4rem;
    width: 100%;
    max-width: 100%;
    overflow-x: hidden;
    overflow-x: clip;
}

/* Header & Navigation */
.site-header {
    background-color: var(--bg-surface);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    background-color: rgba(255, 255, 255, 0.95);
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
}

[data-theme="dark"] .site-header {
    background-color: rgba(17, 24, 39, 0.9);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.logo-link {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    font-size: 1.35rem;
    font-weight: 800;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.logo-badge {
    background: linear-gradient(135deg, #4f46e5 0%, #06b6d4 100%);
    color: #ffffff;
    width: 38px;
    height: 38px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 10px rgba(79, 70, 229, 0.3);
}

.logo-text span {
    color: var(--primary);
}

.nav-desktop {
    display: flex;
    align-items: center;
    gap: 1.75rem;
}

.nav-link {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-secondary);
}

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

.header-actions {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

/* Theme Toggle Button */
.theme-toggle {
    background: var(--bg-surface-subtle);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    width: 40px;
    height: 40px;
    border-radius: var(--radius-full);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
}

.theme-toggle:hover {
    background: var(--primary-light);
    color: var(--primary);
    border-color: var(--primary);
}

.mobile-menu-toggle {
    display: none;
    background: none;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.5rem;
    border-radius: var(--radius-sm);
    cursor: pointer;
}

/* Mobile Nav Drawer */
.mobile-nav {
    display: none;
    background: var(--bg-surface);
    border-bottom: 1px solid var(--border-color);
    padding: 1.25rem;
}

.mobile-nav.open {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

/* Hero Section */
.hero {
    padding: 3.5rem 0 2.5rem;
    text-align: center;
    background: radial-gradient(circle at 50% 10%, rgba(99, 102, 241, 0.08) 0%, transparent 60%);
}

.hero-title {
    font-size: 2.75rem;
    font-weight: 800;
    letter-spacing: -0.03em;
    margin-bottom: 0.75rem;
}

.hero-gradient {
    background: linear-gradient(135deg, var(--primary) 0%, #06b6d4 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-subtitle {
    font-size: 1.15rem;
    color: var(--text-muted);
    max-width: 650px;
    margin: 0 auto 2rem;
}

/* Search Box */
.search-container {
    max-width: 580px;
    margin: 0 auto 2rem;
    position: relative;
}

.search-input {
    width: 100%;
    padding: 1rem 1.25rem 1rem 3.25rem;
    font-size: 1rem;
    border-radius: var(--radius-full);
    border: 1px solid var(--border-color);
    background: var(--bg-surface);
    color: var(--text-primary);
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.search-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px var(--primary-light);
}

.search-icon {
    position: absolute;
    left: 1.25rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
    pointer-events: none;
}

/* Section Header */
.section-header {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    margin-bottom: 1.75rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--border-color);
}

.section-title {
    font-size: 1.5rem;
    margin: 0;
}

.section-link {
    font-size: 0.9rem;
    font-weight: 600;
}

/* Grid Layouts */
.grid-3 {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(min(100%, 300px), 1fr));
    gap: 1.5rem;
}

.grid-2 {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(min(100%, 320px), 1fr));
    gap: 1.5rem;
}

.grid-4 {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(min(100%, 220px), 1fr));
    gap: 1.25rem;
}

/* Card Styles */
.card {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
}

.card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
    border-color: var(--primary-light);
}

.card-icon {
    width: 44px;
    height: 44px;
    border-radius: var(--radius-md);
    background: var(--primary-light);
    color: var(--primary);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
    font-size: 1.25rem;
}

.card-title {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.card-desc {
    font-size: 0.92rem;
    color: var(--text-secondary);
    margin-bottom: 1.25rem;
    flex-grow: 1;
}

.card-footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.badge {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    padding: 0.25rem 0.65rem;
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border-radius: var(--radius-full);
    background: var(--bg-surface-subtle);
    color: var(--text-secondary);
}

.badge-primary {
    background: var(--primary-light);
    color: var(--primary-text);
}

/* Calculator Page Form & Layout */
.calc-layout {
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    gap: 2rem;
    margin-top: 1.5rem;
    width: 100%;
    max-width: 100%;
}

.calc-layout > * {
    min-width: 0;
    max-width: 100%;
}

@media (max-width: 900px) {
    .calc-layout {
        grid-template-columns: 1fr;
    }
}

.calc-box {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 2rem;
    box-shadow: var(--shadow-md);
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
    overflow-x: hidden;
}

.form-group {
    margin-bottom: 1.25rem;
}

.form-label {
    display: block;
    font-weight: 600;
    font-size: 0.95rem;
    margin-bottom: 0.4rem;
    color: var(--text-primary);
}

.form-hint {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: 0.25rem;
}

.form-input, .form-select, .form-textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    font-size: 1rem;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
    background: var(--bg-surface);
    color: var(--text-primary);
    transition: var(--transition);
    font-family: inherit;
}

.form-input:focus, .form-select:focus, .form-textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-light);
}

.btn-group {
    display: flex;
    gap: 0.75rem;
    margin-top: 1.5rem;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    font-size: 0.95rem;
    font-weight: 600;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition);
    border: none;
}

.btn-primary {
    background: var(--primary);
    color: #ffffff;
    box-shadow: 0 4px 10px rgba(79, 70, 229, 0.25);
}

.btn-primary:hover {
    background: var(--primary-hover);
    color: #ffffff;
    box-shadow: 0 6px 14px rgba(79, 70, 229, 0.35);
}

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

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

.btn-sm {
    padding: 0.4rem 0.85rem;
    font-size: 0.85rem;
}

/* Button Loading & Spinner State */
.btn.loading {
    position: relative;
    color: transparent !important;
    pointer-events: none;
}

.btn.loading::after {
    content: "";
    position: absolute;
    width: 1.15rem;
    height: 1.15rem;
    top: 50%;
    left: 50%;
    margin-top: -0.575rem;
    margin-left: -0.575rem;
    border: 2.5px solid rgba(255, 255, 255, 0.35);
    border-radius: 50%;
    border-top-color: #ffffff;
    animation: btn-spin 0.65s linear infinite;
}

.btn-secondary.loading::after {
    border-color: rgba(79, 70, 229, 0.25);
    border-top-color: var(--primary);
}

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

.result-card.calculating {
    opacity: 0.65;
    transition: opacity 0.15s ease-in-out;
}

/* Quick Preset Chips */
.preset-chips {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-top: 0.5rem;
}

.preset-chip {
    background: var(--bg-surface-subtle);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.25rem 0.65rem;
    border-radius: var(--radius-full);
    font-size: 0.8rem;
    cursor: pointer;
    transition: var(--transition);
}

.preset-chip:hover {
    background: var(--primary-light);
    color: var(--primary);
    border-color: var(--primary);
}

/* Result Box */
.result-card {
    background: linear-gradient(145deg, var(--bg-surface) 0%, var(--bg-surface-subtle) 100%);
    border: 2px solid var(--primary-light);
    border-radius: var(--radius-lg);
    padding: 1.75rem;
    box-shadow: var(--shadow-md);
    position: sticky;
    top: 90px;
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
    overflow-x: hidden;
}

.result-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 1rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--border-color);
}

.result-title {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--text-primary);
    margin: 0;
}

.result-main {
    margin: 1.25rem 0;
}

.result-hero-val {
    font-size: 2.25rem;
    font-weight: 800;
    color: var(--primary);
    line-height: 1.15;
    letter-spacing: -0.02em;
}

.result-hero-sub {
    font-size: 1rem;
    color: var(--text-muted);
    margin-top: 0.35rem;
}

.result-metrics {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.75rem;
    margin: 1.25rem 0;
}

.metric-item {
    background: var(--bg-surface);
    padding: 0.85rem;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.metric-label {
    font-size: 0.78rem;
    color: var(--text-muted);
    text-transform: uppercase;
    font-weight: 700;
    margin-bottom: 0.2rem;
}

.metric-value {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-primary);
}

.copy-btn {
    width: 100%;
    margin-top: 1rem;
}

/* Breadcrumbs */
.breadcrumbs {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.85rem;
    color: var(--text-muted);
    margin: 1.25rem 0;
    flex-wrap: wrap;
    word-break: break-word;
    line-height: 1.6;
}

.breadcrumbs span {
    color: var(--border-color);
}

/* Educational Content & Sections */
.article-content {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 2.25rem;
    box-shadow: var(--shadow-sm);
    margin-top: 2.5rem;
    max-width: 100%;
    overflow-x: hidden;
}

.article-content table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
    display: block;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    max-width: 100%;
}

.article-content th, .article-content td {
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    text-align: left;
}

.article-content th {
    background: var(--bg-surface-subtle);
    font-weight: 700;
}

.article-content blockquote {
    border-left: 4px solid var(--primary);
    padding: 0.75rem 1.25rem;
    margin: 1.25rem 0;
    background: var(--primary-light);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    color: var(--text-primary);
    font-style: italic;
}

/* Table of Contents */
.toc-box {
    background: var(--bg-surface-subtle);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 1.25rem;
    margin-bottom: 2rem;
}

.toc-title {
    font-size: 1.05rem;
    margin-bottom: 0.75rem;
}

.toc-list {
    list-style: none;
    padding-left: 0;
}

.toc-list li {
    margin-bottom: 0.4rem;
}

.toc-list a {
    font-size: 0.92rem;
    color: var(--text-secondary);
}

.toc-list a:hover {
    color: var(--primary);
    padding-left: 4px;
}

/* FAQ Accordion */
.faq-item {
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    margin-bottom: 0.75rem;
    overflow: hidden;
    background: var(--bg-surface);
}

.faq-question {
    width: 100%;
    padding: 1rem 1.25rem;
    text-align: left;
    background: none;
    border: none;
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.faq-answer {
    padding: 0 1.25rem 1rem;
    font-size: 0.95rem;
    color: var(--text-secondary);
}

/* Author Box */
.author-box {
    display: flex;
    gap: 1.25rem;
    align-items: center;
    background: var(--bg-surface-subtle);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    margin-top: 2rem;
}

.author-avatar {
    width: 70px;
    height: 70px;
    border-radius: var(--radius-full);
    object-fit: cover;
    background: var(--primary-light);
    border: 2px solid var(--primary);
}

.author-info h4 {
    margin-bottom: 0.25rem;
}

.author-creds {
    font-size: 0.85rem;
    color: var(--primary);
    font-weight: 600;
    margin-bottom: 0.4rem;
}

.author-bio {
    font-size: 0.9rem;
    margin: 0;
    color: var(--text-secondary);
}

/* Ad Placement Slots (AdSense Ready) */
.ad-slot {
    margin: 1.75rem 0;
    text-align: center;
    min-height: 90px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: var(--bg-surface-subtle);
    border: 1px dashed var(--border-color);
    border-radius: var(--radius-md);
    padding: 0.75rem;
}

.ad-label {
    font-size: 0.7rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
    margin-bottom: 0.4rem;
}

/* Footer */
.site-footer {
    background: var(--bg-surface);
    border-top: 1px solid var(--border-color);
    padding: 4rem 0 2rem;
    margin-top: auto;
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
    overflow-x: hidden;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 2.5rem;
    margin-bottom: 3rem;
}

@media (max-width: 800px) {
    .footer-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 550px) {
    .footer-grid {
        grid-template-columns: 1fr;
    }
}

.footer-brand p {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-top: 0.75rem;
    max-width: 320px;
}

.footer-col h4 {
    font-size: 1rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

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

.footer-links li {
    margin-bottom: 0.5rem;
}

.footer-links a {
    font-size: 0.9rem;
    color: var(--text-muted);
}

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

.footer-bottom {
    border-top: 1px solid var(--border-color);
    padding-top: 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.85rem;
    color: var(--text-muted);
    flex-wrap: wrap;
    gap: 1rem;
}

/* Toast Notifications */
.toast-container {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    z-index: 9999;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.toast {
    background: var(--text-primary);
    color: var(--bg-main);
    padding: 0.75rem 1.25rem;
    border-radius: var(--radius-md);
    font-size: 0.9rem;
    font-weight: 600;
    box-shadow: var(--shadow-lg);
    animation: slideUp 0.25s ease-out;
}

@keyframes slideUp {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* =============================================================
   Responsive Mobile & Tablet Optimizations
   ============================================================= */

@media (max-width: 900px) {
    .calc-layout {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .result-card {
        position: static;
        top: 0;
    }
}

@media (max-width: 768px) {
    .nav-desktop { 
        display: none; 
    }
    
    .mobile-menu-toggle { 
        display: inline-flex; 
    }
    
    .hero {
        padding: 2.25rem 0 1.75rem;
    }
    
    .hero-title { 
        font-size: 1.95rem; 
        letter-spacing: -0.02em;
    }
    
    h1 { 
        font-size: 1.75rem; 
        word-break: break-word;
    }
    
    h2 { 
        font-size: 1.35rem; 
    }
    
    h3 { 
        font-size: 1.15rem; 
    }
    
    .container {
        padding: 0 1rem;
        max-width: 100%;
        overflow-x: hidden;
    }
    
    .calc-box, 
    .result-card, 
    .article-content {
        padding: 1.25rem 1rem;
        border-radius: var(--radius-md);
    }
    
    .grid-2, 
    .grid-3 {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 1.75rem;
    }
    
    .footer-bottom {
        flex-direction: column;
        text-align: center;
        gap: 0.75rem;
    }
    
    .author-box {
        flex-direction: column;
        text-align: center;
        padding: 1.25rem 1rem;
    }
}

@media (max-width: 480px) {
    html {
        font-size: 15px;
    }
    
    /* Prevent iOS Safari auto-zoom on input focus */
    .form-input, 
    .form-select, 
    .form-textarea {
        font-size: 16px !important;
        padding: 0.7rem 0.85rem;
    }
    
    .container {
        padding: 0 0.85rem;
    }
    
    .header-inner {
        height: 60px;
    }
    
    .logo-text {
        font-size: 1.2rem;
    }
    
    .logo-badge {
        width: 32px;
        height: 32px;
    }
    
    .hero {
        padding: 1.75rem 0 1.25rem;
    }
    
    .hero-title {
        font-size: 1.6rem;
    }
    
    .hero-subtitle {
        font-size: 0.95rem;
        margin-bottom: 1.25rem;
    }
    
    .calc-box {
        padding: 1.15rem 0.85rem;
    }
    
    .result-card {
        padding: 1.15rem 0.85rem;
    }
    
    .result-hero-val {
        font-size: 1.75rem;
        word-break: break-word;
    }
    
    .result-metrics {
        grid-template-columns: 1fr;
        gap: 0.5rem;
    }
    
    .btn-group {
        display: flex;
        gap: 0.5rem;
    }
    
    .btn-group .btn {
        flex: 1 1 calc(50% - 0.25rem);
        min-width: 0;
        padding: 0.75rem 0.5rem;
        font-size: 0.9rem;
        justify-content: center;
    }
    
    .preset-chips {
        gap: 0.35rem;
    }
    
    .preset-chip {
        font-size: 0.75rem;
        padding: 0.2rem 0.55rem;
    }
    
    .article-content {
        padding: 1.15rem 0.85rem;
    }
}