@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800;900&family=JetBrains+Mono:wght@400;500;600&display=swap');

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

:root {
    --bg-primary: #0f0f13;
    --bg-card: #1a1a2e;
    --bg-input: #0f0f13;
    --text-primary: #e4e4e7;
    --text-secondary: #a1a1aa;
    --text-muted: #71717a;
    --border: rgba(255,255,255,0.06);
    --border-hover: rgba(255,255,255,0.12);
    --accent-1: #fb7185;
    --accent-2: #f43f5e;
    --accent-3: #e11d48;
    --gradient: linear-gradient(135deg, #fb7185, #f43f5e, #e11d48);
    --radius: 1rem;
    --radius-lg: 1.25rem;
    --shadow: 0 4px 24px rgba(0,0,0,0.4);
    --shadow-lg: 0 8px 40px rgba(0,0,0,0.5);
}

.hidden { display: none !important; }

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 1.25rem;
}

/* Header */
.site-header {
    background: rgba(15,15,19,0.85);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
    padding: 1rem 0;
}

.site-header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    text-decoration: none;
    font-weight: 800;
    font-size: 1.25rem;
    color: var(--text-primary);
}

.logo-icon {
    width: 2.2rem;
    height: 2.2rem;
    background: var(--gradient);
    border-radius: 0.6rem;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    font-weight: 700;
    color: #fff;
}

nav { display: flex; gap: 0.25rem; }

nav a {
    color: var(--text-secondary);
    text-decoration: none;
    padding: 0.45rem 0.85rem;
    border-radius: 0.5rem;
    font-size: 0.85rem;
    font-weight: 500;
    transition: all 0.2s;
}

nav a:hover {
    color: var(--text-primary);
    background: rgba(255,255,255,0.05);
}

/* Hero */
.hero {
    text-align: center;
    padding: 3.5rem 0 2rem;
}

.hero h1 {
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 900;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 0.75rem;
    letter-spacing: -0.03em;
}

.hero p {
    color: var(--text-secondary);
    font-size: 1.1rem;
    max-width: 500px;
    margin: 0 auto;
}

/* Ad Slots */
.ad-slot {
    background: var(--bg-card);
    border: 1px dashed var(--border-hover);
    border-radius: var(--radius);
    min-height: 90px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 1.5rem 0;
    color: var(--text-muted);
    font-size: 0.8rem;
}

/* Card */
.card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 2rem;
    box-shadow: var(--shadow);
}

/* Calculator Layout */
.calc-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    margin-bottom: 2rem;
}

.calc-section h3 {
    font-size: 0.85rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

/* Form Inputs */
.input-group {
    margin-bottom: 1.25rem;
}

.input-group label {
    display: block;
    font-weight: 600;
    font-size: 0.9rem;
    margin-bottom: 0.4rem;
    color: var(--text-secondary);
}

.input-wrapper {
    position: relative;
}

.input-wrapper .prefix {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
    font-weight: 600;
    font-size: 1rem;
    pointer-events: none;
}

.input-wrapper .suffix {
    position: absolute;
    right: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
    font-weight: 600;
    font-size: 0.9rem;
    pointer-events: none;
}

input[type="number"] {
    width: 100%;
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 0.85rem 1rem;
    color: var(--text-primary);
    font-family: 'JetBrains Mono', monospace;
    font-size: 1.1rem;
    font-weight: 600;
    transition: all 0.2s;
    -moz-appearance: textfield;
}

input[type="number"]::-webkit-inner-spin-button,
input[type="number"]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

input[type="number"]:focus {
    outline: none;
    border-color: var(--accent-2);
    box-shadow: 0 0 0 3px rgba(244,63,94,0.15);
}

.has-prefix input { padding-left: 2.2rem; }
.has-suffix input { padding-right: 2.5rem; }

/* Tip Quick Buttons */
.tip-buttons {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-bottom: 1rem;
}

.tip-btn {
    background: var(--bg-input);
    border: 1px solid var(--border);
    color: var(--text-secondary);
    padding: 0.55rem 1.1rem;
    border-radius: 2rem;
    font-family: 'Inter', sans-serif;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.tip-btn:hover {
    border-color: var(--accent-1);
    color: var(--accent-1);
    background: rgba(251,113,133,0.08);
}

.tip-btn.active {
    background: var(--gradient);
    border-color: transparent;
    color: #fff;
}

/* Split controls */
.split-controls {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.split-btn {
    width: 2.5rem;
    height: 2.5rem;
    border-radius: 50%;
    border: 1px solid var(--border);
    background: var(--bg-input);
    color: var(--text-primary);
    font-size: 1.2rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
    font-family: 'Inter', sans-serif;
}

.split-btn:hover {
    border-color: var(--accent-1);
    color: var(--accent-1);
}

.split-value {
    font-family: 'JetBrains Mono', monospace;
    font-size: 1.3rem;
    font-weight: 700;
    min-width: 2rem;
    text-align: center;
}

/* Checkbox */
.checkbox-group {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    margin-top: 0.5rem;
    cursor: pointer;
}

.checkbox-group input[type="checkbox"] {
    width: 1.1rem;
    height: 1.1rem;
    accent-color: var(--accent-2);
    cursor: pointer;
}

.checkbox-group label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    cursor: pointer;
    margin-bottom: 0;
}

/* Results */
.results-card {
    background: linear-gradient(135deg, rgba(251,113,133,0.08), rgba(244,63,94,0.05));
    border: 1px solid rgba(251,113,133,0.15);
    border-radius: var(--radius-lg);
    padding: 1.75rem;
}

.result-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.6rem 0;
}

.result-row:not(:last-child) {
    border-bottom: 1px solid rgba(255,255,255,0.05);
}

.result-label {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
}

.result-value {
    font-family: 'JetBrains Mono', monospace;
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-primary);
}

.result-row.total .result-label {
    font-weight: 700;
    color: var(--text-primary);
    font-size: 1rem;
}

.result-row.total .result-value {
    font-size: 1.5rem;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.result-divider {
    height: 1px;
    background: rgba(255,255,255,0.08);
    margin: 0.5rem 0;
}

.per-person-label {
    display: inline-block;
    background: rgba(251,113,133,0.1);
    color: var(--accent-1);
    font-size: 0.7rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 0.2rem 0.5rem;
    border-radius: 0.3rem;
    margin-bottom: 0.5rem;
}

/* Content Section */
.content-section {
    margin-top: 2rem;
}

.content-section h2 {
    font-size: 1.5rem;
    font-weight: 800;
    margin-bottom: 1rem;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.content-section h3 {
    font-size: 1.1rem;
    font-weight: 700;
    margin: 1.5rem 0 0.5rem;
    color: var(--text-primary);
}

.content-section p, .content-section li {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 0.75rem;
}

.content-section ul {
    list-style: none;
    padding: 0;
}

.content-section ul li::before {
    content: "→ ";
    color: var(--accent-1);
    font-weight: 600;
}

.tipping-table {
    width: 100%;
    border-collapse: collapse;
    margin: 1rem 0 1.5rem;
    font-size: 0.9rem;
}

.tipping-table th, .tipping-table td {
    padding: 0.7rem 1rem;
    text-align: left;
    border-bottom: 1px solid var(--border);
}

.tipping-table th {
    color: var(--accent-1);
    font-weight: 700;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.tipping-table td {
    color: var(--text-secondary);
}

/* FAQ */
.faq-item {
    border-bottom: 1px solid var(--border);
    padding: 1rem 0;
}

.faq-item:last-child { border-bottom: none; }

.faq-q {
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.4rem;
}

.faq-a {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Footer */
.site-footer {
    margin-top: 3rem;
    border-top: 1px solid var(--border);
    padding: 2rem 0;
}

.site-footer .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.site-footer p {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.site-footer nav { display: flex; gap: 1.25rem; }

.site-footer nav a {
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.85rem;
    transition: color 0.2s;
}

.site-footer nav a:hover { color: var(--accent-1); }

/* Responsive */
@media (max-width: 768px) {
    .calc-layout {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    .card { padding: 1.25rem; }

    .site-header .container { flex-wrap: wrap; gap: 0.75rem; }

    nav { width: 100%; justify-content: center; }

    .site-footer .container {
        flex-direction: column;
        text-align: center;
    }

    .tipping-table { font-size: 0.8rem; }
    .tipping-table th, .tipping-table td { padding: 0.5rem 0.6rem; }
}