:root {
    --primary: #10B981; /* Emerald green for savings */
    --primary-dark: #059669;
    --secondary: #3B82F6; /* Blue for trust/action */
    --secondary-dark: #2563EB;
    --bg-color: #F3F4F6;
    --card-bg: #FFFFFF;
    --text-main: #1F2937;
    --text-muted: #6B7280;
    --border-color: #E5E7EB;
    --error: #EF4444;
    
    --radius-md: 12px;
    --radius-lg: 16px;
    
    --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);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.5;
    padding-bottom: 80px; /* Space for anchor ad */
}

.container {
    max-width: 600px;
    margin: 0 auto;
    padding: 0 16px;
}

/* Typography */
h1 {
    font-size: 1.75rem;
    font-weight: 700;
    text-align: center;
    color: var(--primary-dark);
}
h2 {
    font-size: 1.5rem;
    margin-bottom: 12px;
}
h3 {
    font-size: 1.25rem;
    margin: 16px 0 8px;
}
p {
    margin-bottom: 16px;
}

/* Header */
header {
    padding: 24px 0 16px;
    text-align: center;
}
header p {
    color: var(--text-muted);
    font-size: 1rem;
    margin-bottom: 0;
}

/* Ads Containers - FIXED DIMENSIONS to avoid CLS */
.ad-container {
    background-color: #E5E7EB;
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 16px auto;
    overflow: hidden;
}
.ad-placeholder-text {
    color: #9CA3AF;
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}
.ad-header {
    width: 100%;
    max-width: 728px;
    height: 90px;
}
.ad-in-feed {
    width: 300px;
    height: 250px;
}
.ad-anchor {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 50px; /* Or 90px depending on standard anchor ad size */
    z-index: 1000;
    margin: 0;
}
@media (min-width: 768px) {
    .ad-anchor {
        display: none; /* Often anchor ads are mobile only */
    }
}

/* Calculator Card */
.calculator-card {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    padding: 24px;
    box-shadow: var(--shadow-md);
    margin-bottom: 24px;
}

/* Inputs */
.input-group {
    margin-bottom: 24px;
}
label {
    display: block;
    font-weight: 600;
    margin-bottom: 8px;
    font-size: 0.95rem;
}
.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}
.currency-symbol {
    position: absolute;
    left: 16px;
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-muted);
}
input[type="text"], input[type="number"] {
    width: 100%;
    padding: 16px 16px 16px 40px; /* Space for symbol */
    font-size: 1.5rem;
    font-weight: 700;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    outline: none;
    transition: border-color 0.2s;
    background: var(--bg-color);
}
input[type="text"]:focus, input[type="number"]:focus {
    border-color: var(--primary);
    background: var(--card-bg);
}

/* Slider & Custom Discount */
.discount-display {
    font-size: 2rem;
    font-weight: 800;
    color: var(--primary);
    text-align: center;
    margin-bottom: 16px;
    display: flex;
    justify-content: center;
    align-items: baseline;
}
.discount-display input {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--primary);
    width: 80px;
    text-align: right;
    border: none;
    background: transparent;
    outline: none;
    padding: 0;
    -moz-appearance: textfield;
}
.discount-display input::-webkit-outer-spin-button,
.discount-display input::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}
.discount-display span {
    font-size: 2rem;
    margin-left: 4px;
}
input[type="range"] {
    width: 100%;
    height: 8px;
    background: var(--border-color);
    border-radius: 4px;
    outline: none;
    appearance: none;
    margin-bottom: 16px;
}
input[type="range"]::-webkit-slider-thumb {
    appearance: none;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background: var(--primary);
    cursor: pointer;
    box-shadow: var(--shadow-sm);
}

/* Quick Discount Buttons */
.quick-discounts {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
}
.btn-quick {
    padding: 10px;
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 1rem;
    color: var(--text-main);
    cursor: pointer;
    transition: all 0.2s;
}
.btn-quick:active, .btn-quick.active {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}

/* Advanced Options */
.advanced-options {
    background: var(--bg-color);
    border-radius: var(--radius-md);
    padding: 16px;
    margin-bottom: 24px;
}
.toggle-group {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}
.toggle-group:last-child {
    margin-bottom: 0;
}
.toggle-group label:first-child {
    margin-bottom: 0;
    font-weight: 500;
}

/* Toggle Switch */
.switch {
    position: relative;
    display: inline-block;
    width: 50px;
    height: 28px;
}
.switch input { 
    opacity: 0;
    width: 0;
    height: 0;
}
.slider {
    position: absolute;
    cursor: pointer;
    top: 0; left: 0; right: 0; bottom: 0;
    background-color: #ccc;
    transition: .4s;
}
.slider:before {
    position: absolute;
    content: "";
    height: 20px;
    width: 20px;
    left: 4px;
    bottom: 4px;
    background-color: white;
    transition: .4s;
}
input:checked + .slider {
    background-color: var(--primary);
}
input:checked + .slider:before {
    transform: translateX(22px);
}
.slider.round {
    border-radius: 34px;
}
.slider.round:before {
    border-radius: 50%;
}

.hidden {
    display: none !important;
}

/* Results Panel */
.results-panel {
    background: #F8FAFC;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 24px;
    text-align: center;
}
.result-item {
    display: flex;
    flex-direction: column;
    margin-bottom: 16px;
}
.result-item span {
    font-size: 0.95rem;
    color: var(--text-muted);
    font-weight: 500;
}
.result-item strong {
    font-size: 2.5rem;
    font-weight: 800;
    line-height: 1.1;
}
.result-item.highlight strong {
    color: var(--text-main);
}
.result-item.success strong {
    color: var(--primary);
}
.breakdown {
    margin-bottom: 24px;
    color: var(--text-muted);
    font-size: 0.85rem;
}

/* Buttons */
.btn {
    display: inline-block;
    width: 100%;
    padding: 14px;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 1rem;
    text-align: center;
    cursor: pointer;
    border: none;
    transition: background 0.2s;
}
.btn-outline {
    background: transparent;
    border: 2px solid var(--border-color);
    color: var(--text-muted);
}
.btn-outline:active {
    background: var(--border-color);
}
.btn-secondary {
    background: var(--secondary);
    color: white;
}
.btn-secondary:active {
    background: var(--secondary-dark);
}

/* Install Prompt */
#installPrompt {
    background: var(--card-bg);
    padding: 16px;
    border-radius: var(--radius-md);
    margin-bottom: 16px;
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
    gap: 12px;
}
#installPrompt p {
    margin: 0;
    font-weight: 500;
    text-align: center;
}

/* SEO Content */
.seo-content {
    background: var(--card-bg);
    padding: 24px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    margin-bottom: 24px;
}
.seo-content ul {
    margin-left: 20px;
    margin-bottom: 16px;
}
.seo-content li {
    margin-bottom: 8px;
}
.example-box {
    background: #F8FAFC;
    border-left: 4px solid var(--secondary);
    padding: 12px 16px;
    margin: 16px 0;
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

/* Secondary Calculators Cards */
.secondary-card, .merchant-card {
    background: var(--card-bg);
}
.secondary-card h2, .merchant-card h2 {
    font-size: 1.25rem;
    color: var(--text-main);
    text-align: center;
}
.subtitle {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-bottom: 24px;
}
.calc-grid {
    display: flex;
    flex-direction: column;
    gap: 20px;
}
.divider {
    border: none;
    border-top: 1px solid var(--border-color);
    margin: 4px 0;
}
.sub-calculator h3 {
    font-size: 1rem;
    color: var(--primary-dark);
    margin-bottom: 12px;
}
.inline-inputs {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 12px;
    font-size: 0.95rem;
}
.inline-inputs input {
    padding: 8px 12px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    width: 100px;
    font-weight: 600;
    font-size: 1rem;
    outline: none;
    transition: border-color 0.2s;
}
.inline-inputs input:focus {
    border-color: var(--secondary);
}
.sub-result {
    font-size: 1rem;
    color: var(--text-muted);
}
.sub-result strong {
    font-size: 1.25rem;
    color: var(--text-main);
    margin-left: 4px;
}

/* Footer */
footer {
    text-align: center;
    padding: 24px 0;
    color: var(--text-muted);
    font-size: 0.875rem;
}
.footer-nav {
    margin-top: 12px;
    display: flex;
    justify-content: center;
    gap: 16px;
    flex-wrap: wrap;
}
.footer-nav a {
    color: var(--secondary);
    text-decoration: none;
}
.footer-nav a:hover {
    text-decoration: underline;
}