:root {
    --primary: #6366f1;
    --primary-hover: #4f46e5;
    --bg-gradient: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
    --card-bg: rgba(255, 255, 255, 0.9);
    --text-main: #1e293b;
    --text-muted: #64748b;
    --border: #e2e8f0;
    --shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
    --radius: 16px;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background: var(--bg-gradient);
    color: var(--text-main);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    line-height: 1.5;
    padding: 20px;
}

.app-container {
    width: 100%;
    max-width: 1200px;
}

.top-nav {
    margin-bottom: 1.5rem;
    display: flex;
    justify-content: flex-start;
}

.back-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 500;
    transition: color 0.2s ease;
}

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

.back-link svg {
    width: 16px;
    height: 16px;
}

header {
    text-align: center;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 2rem;
    font-weight: 700;
    color: #0f172a;
    margin-bottom: 0.5rem;
    letter-spacing: -0.025em;
}

header p {
    color: var(--text-muted);
    font-size: 0.95rem;
}

.calculator-card {
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.5);
    padding: 2.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    position: relative;
    overflow: hidden;
    margin: 0 auto;
    /* Center on desktop */
}

.calculator-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--primary);
}

.input-section {
    display: grid;
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-group label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.input-wrapper span {
    position: absolute;
    color: var(--text-muted);
    font-weight: 500;
}

.input-wrapper span:first-child {
    left: 1rem;
}

.input-wrapper span:last-child {
    right: 1rem;
}

.input-wrapper input {
    width: 100%;
    padding: 0.75rem 1rem;
    padding-left: 2rem;
    /* space for $ */
    padding-right: 2rem;
    /* space for % if needed */
    border: 2px solid var(--border);
    border-radius: 10px;
    font-size: 1.125rem;
    font-weight: 500;
    color: var(--text-main);
    transition: all 0.2s ease;
    background: #fff;
}

#pmc-margin {
    padding-left: 1rem;
}

.input-wrapper input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

.results-section {
    background: #f1f5f9;
    border-radius: 12px;
    padding: 1.5rem;
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 1rem;
    margin-bottom: 2rem;
}

.result-item label {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    margin-bottom: 0.25rem;
    display: block;
}

.result-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
}

.actions {
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: 1rem;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1rem;
    border-radius: 10px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    border: none;
    font-size: 0.95rem;
}

.btn svg {
    width: 18px;
    height: 18px;
}

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

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
}

.btn-secondary {
    background: white;
    color: var(--text-main);
    border: 2px solid var(--border);
}

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

.feedback-toast {
    position: absolute;
    bottom: 1rem;
    left: 50%;
    transform: translateX(-50%) translateY(100%);
    background: #1e293b;
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 9999px;
    font-size: 0.875rem;
    opacity: 0;
    transition: all 0.3s ease;
    pointer-events: none;
    z-index: 10;
}

.feedback-toast.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

footer {
    text-align: center;
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border);
    color: var(--text-muted);
    font-size: 0.875rem;
}

@media (min-width: 1024px) {
    .calculator-card {
        max-width: 600px;
        /* Keep calculator readable */
    }
}

/* SEO Article Styles */
.seo-article {
    margin-top: 4rem;
    text-align: left;
    background: var(--card-bg);
    padding: 2.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    border: 1px solid rgba(255, 255, 255, 0.5);
}

.seo-article h2 {
    font-size: 1.75rem;
    margin-bottom: 1.5rem;
    color: #0f172a;
    line-height: 1.2;
}

.seo-article h3 {
    font-size: 1.25rem;
    margin: 2rem 0 1rem;
    color: #1e293b;
}

.seo-article p {
    margin-bottom: 1.25rem;
    color: #475569;
    font-size: 1rem;
}

.seo-article blockquote {
    padding: 1.5rem;
    background: #f8fafc;
    border-left: 4px solid var(--primary);
    margin: 1.5rem 0;
    border-radius: 0 8px 8px 0;
    font-family: monospace;
}

.seo-article ul,
.seo-article ol {
    margin-bottom: 1.5rem;
    padding-left: 1.5rem;
    color: #475569;
}

.seo-article li {
    margin-bottom: 0.5rem;
}

.table-wrapper {
    overflow-x: auto;
    margin: 1.5rem 0;
}

table {
    width: 100%;
    border-collapse: collapse;
    background: #fff;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

th {
    background: #f1f5f9;
    padding: 0.75rem 1rem;
    text-align: left;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-muted);
    border-bottom: 2px solid var(--border);
}

td {
    padding: 0.75rem 1rem;
    border-bottom: 1px solid var(--border);
    font-size: 0.95rem;
}

@media (max-width: 500px) {
    .results-section {
        grid-template-columns: 1fr;
    }

    .markup-result {
        border-top: 1px solid #e2e8f0;
        padding-top: 0.5rem;
    }
}

@media (max-width: 400px) {
    .calculator-card {
        padding: 1.5rem;
    }

    .results-section {
        grid-template-columns: 1fr;
    }

    .actions {
        grid-template-columns: 1fr;
    }
}

.pulse {
    animation: pulse-out 0.4s ease-out;
}

@keyframes pulse-out {
    0% {
        transform: scale(1);
    }

    50% {
        transform: scale(1.05);
    }

    100% {
        transform: scale(1);
    }
}