/* ══════════════════════════════════════════════════
   TileTally — The Symmetrical Tile Layout Planner
   Design: Clean dark slate with cool blue accent
   Evokes bathroom/kitchen tile aesthetics
   ══════════════════════════════════════════════════ */

/* ── CSS Custom Properties ── */
:root {
    --clr-bg: #0c1017;
    --clr-bg-gradient: linear-gradient(145deg, #0c1017 0%, #0f1520 50%, #0c1017 100%);
    --clr-surface: #141922;
    --clr-surface-2: #1c222e;
    --clr-surface-3: #232a38;
    --clr-border: #2a3040;
    --clr-border-hover: #3a4560;
    --clr-text: #e6eaf2;
    --clr-text-muted: #7d8ba0;
    --clr-text-dim: #4e5a70;
    --clr-accent: #3b82f6;
    --clr-accent-hover: #2563eb;
    --clr-accent-glow: rgba(59, 130, 246, 0.12);
    --clr-accent-glow-strong: rgba(59, 130, 246, 0.25);
    --clr-tile-full: #475569;
    --clr-tile-full-hover: #556478;
    --clr-tile-cut: #3b82f6;
    --clr-tile-cut-light: #60a5fa;
    --clr-tile-corner: #2563eb;
    --clr-grout: #1e293b;
    --clr-chalk: #f97316;
    --clr-chalk-glow: rgba(249, 115, 22, 0.3);
    --clr-success: #22c55e;
    --clr-success-glow: rgba(34, 197, 94, 0.15);
    --clr-warning: #f59e0b;
    --clr-warning-glow: rgba(245, 158, 11, 0.12);
    --clr-danger: #ef4444;
    --clr-danger-glow: rgba(239, 68, 68, 0.12);
    --radius: 12px;
    --radius-sm: 8px;
    --radius-xs: 4px;
    --shadow: 0 4px 24px rgba(0, 0, 0, 0.35);
    --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.45);
    --shadow-glow-blue: 0 0 30px rgba(59, 130, 246, 0.2);
    --font-sans: 'Outfit', 'Inter', system-ui, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
    --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-bounce: 0.6s cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* ── Reset ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; scroll-behavior: smooth; }
body {
    font-family: var(--font-sans);
    background: var(--clr-bg);
    color: var(--clr-text);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}
.container { max-width: 1100px; margin: 0 auto; padding: 0 1rem; }

/* ═══════════════════════════════════════════
   AD SLOTS
   ═══════════════════════════════════════════ */
.ad-slot {
    display: flex; align-items: center; justify-content: center;
    border: 1px dashed var(--clr-border); color: var(--clr-text-dim);
    font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.06em;
    background: var(--clr-surface); border-radius: var(--radius-xs);
}
.ad-slot--mobile { height: 50px; max-width: 320px; margin: 0 auto 1rem; }
.ad-slot--desktop { display: none; height: 90px; max-width: 728px; margin: 1.5rem auto; }
@media (min-width: 768px) {
    .ad-slot--mobile { display: none; }
    .ad-slot--desktop { display: flex; }
}

/* ═══════════════════════════════════════════
   HEADER
   ═══════════════════════════════════════════ */
.site-header {
    text-align: center;
    padding: 2.5rem 1rem 1.5rem;
    background: linear-gradient(180deg, var(--clr-surface) 0%, var(--clr-bg) 100%);
    border-bottom: 1px solid var(--clr-border);
    position: relative;
}
.site-header::after {
    content: '';
    position: absolute;
    bottom: -1px; left: 0; right: 0;
    height: 2px;
    background: linear-gradient(90deg, transparent, var(--clr-accent), transparent);
    opacity: 0.4;
}
.brand { display: flex; align-items: center; justify-content: center; gap: 0.6rem; }
.brand-icon { font-size: 2rem; }
.brand-name { font-size: 1.75rem; font-weight: 800; letter-spacing: -0.02em; }
.brand-accent { color: var(--clr-accent); }
.brand-tagline { font-size: 0.95rem; color: var(--clr-text-muted); margin-top: 0.25rem; font-weight: 500; }
.brand-subtitle { font-size: 0.85rem; color: var(--clr-text-muted); margin-top: 0.5rem; opacity: 0.7; }

/* ═══════════════════════════════════════════
   PRIVACY BADGE
   ═══════════════════════════════════════════ */
.privacy-badge {
    display: flex; align-items: center; gap: 0.5rem; justify-content: center;
    padding: 0.6rem 1rem; margin: 1.5rem auto; max-width: 420px;
    background: var(--clr-accent-glow); border: 1px solid rgba(59, 130, 246, 0.3);
    border-radius: 100px; font-size: 0.78rem; font-weight: 500; color: var(--clr-accent);
}

/* ═══════════════════════════════════════════
   APP GRID
   ═══════════════════════════════════════════ */
.app-grid { display: grid; gap: 1.5rem; margin-top: 1.5rem; }
@media (min-width: 768px) { .app-grid { grid-template-columns: 1fr 1fr; align-items: start; } }

/* ═══════════════════════════════════════════
   PANELS
   ═══════════════════════════════════════════ */
.panel {
    background: var(--clr-surface);
    border: 1px solid var(--clr-border);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
}
.panel-title {
    font-size: 1.1rem; font-weight: 700; margin-bottom: 1.25rem;
    padding-bottom: 0.75rem; border-bottom: 1px solid var(--clr-border);
}

/* ═══════════════════════════════════════════
   INPUT FIELDSETS
   ═══════════════════════════════════════════ */
.input-fieldset {
    border: 1px solid var(--clr-border); border-radius: var(--radius-sm);
    padding: 1rem; margin-bottom: 1rem;
}
.input-fieldset legend {
    font-size: 0.8rem; font-weight: 700; text-transform: uppercase;
    letter-spacing: 0.06em; color: var(--clr-accent); padding: 0 0.4rem;
}

.input-row { display: flex; gap: 0.75rem; }
.input-row .input-group { flex: 1; }
.input-group--unit { max-width: 120px; }

.input-group { margin-bottom: 0.85rem; }
.input-group label {
    display: block; font-size: 0.8rem; font-weight: 600;
    color: var(--clr-text-muted); margin-bottom: 0.3rem;
}
.input-group input, .input-group select {
    width: 100%; padding: 0.65rem 0.85rem; font-size: 0.95rem;
    font-family: var(--font-mono); background: var(--clr-surface-2);
    border: 1px solid var(--clr-border); border-radius: var(--radius-sm);
    color: var(--clr-text); transition: border-color var(--transition), box-shadow var(--transition);
}
.input-group input:focus, .input-group select:focus {
    outline: none; border-color: var(--clr-accent); box-shadow: 0 0 0 3px var(--clr-accent-glow);
}
.input-group input::placeholder { color: var(--clr-text-muted); opacity: 0.5; }
.input-group input.input-error { border-color: var(--clr-danger); box-shadow: 0 0 0 3px var(--clr-danger-glow); }
.input-hint { font-size: 0.72rem; color: var(--clr-text-muted); margin-top: 0.25rem; display: block; }

/* ═══════════════════════════════════════════
   PRESET BUTTONS
   ═══════════════════════════════════════════ */
.preset-row {
    display: flex; flex-wrap: wrap; gap: 0.4rem; align-items: center;
    margin-bottom: 0.75rem; margin-top: -0.25rem;
}
.preset-label {
    font-size: 0.72rem; color: var(--clr-text-muted); font-weight: 600;
    text-transform: uppercase; letter-spacing: 0.05em; margin-right: 0.25rem;
}
.btn-preset {
    padding: 0.3rem 0.6rem; font-size: 0.72rem; font-weight: 600;
    font-family: var(--font-mono); color: var(--clr-text-muted);
    background: var(--clr-surface-2); border: 1px solid var(--clr-border);
    border-radius: var(--radius-xs); cursor: pointer;
    transition: all var(--transition);
}
.btn-preset:hover { color: var(--clr-text); border-color: var(--clr-border-hover); background: var(--clr-surface-3); }
.btn-preset.active {
    color: var(--clr-accent); border-color: var(--clr-accent);
    background: var(--clr-accent-glow); box-shadow: 0 0 10px var(--clr-accent-glow);
}

/* ═══════════════════════════════════════════
   TOGGLE BUTTONS
   ═══════════════════════════════════════════ */
.toggle-row {
    display: flex; align-items: center; gap: 0.75rem;
    margin-bottom: 0.75rem; flex-wrap: wrap;
}
.toggle-label {
    font-size: 0.78rem; color: var(--clr-text-muted); font-weight: 600;
}
.btn-toggle-group {
    display: flex; gap: 0;
    border: 1px solid var(--clr-border); border-radius: var(--radius-sm); overflow: hidden;
}
.btn-toggle {
    padding: 0.35rem 0.75rem; font-size: 0.75rem; font-weight: 600;
    font-family: var(--font-sans); color: var(--clr-text-muted);
    background: var(--clr-surface-2); border: none; cursor: pointer;
    transition: all var(--transition);
    border-right: 1px solid var(--clr-border);
}
.btn-toggle:last-child { border-right: none; }
.btn-toggle:hover { color: var(--clr-text); background: var(--clr-surface-3); }
.btn-toggle.active {
    color: #fff; background: var(--clr-accent);
    box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.2);
}

/* ═══════════════════════════════════════════
   SLIVER SLIDER
   ═══════════════════════════════════════════ */
.sliver-row {
    margin-bottom: 0.5rem;
}
.sliver-row label {
    font-size: 0.78rem; color: var(--clr-text-muted); font-weight: 600;
    display: block; margin-bottom: 0.3rem;
}
.sliver-row label strong { color: var(--clr-accent); }
.sliver-slider {
    width: 100%; height: 6px; appearance: none; -webkit-appearance: none;
    background: var(--clr-surface-3); border-radius: 3px; outline: none;
    cursor: pointer;
}
.sliver-slider::-webkit-slider-thumb {
    -webkit-appearance: none; appearance: none;
    width: 18px; height: 18px; border-radius: 50%;
    background: var(--clr-accent); cursor: pointer;
    box-shadow: 0 2px 8px rgba(59, 130, 246, 0.3);
    transition: transform var(--transition);
}
.sliver-slider::-webkit-slider-thumb:hover { transform: scale(1.15); }
.sliver-slider::-moz-range-thumb {
    width: 18px; height: 18px; border-radius: 50%;
    background: var(--clr-accent); cursor: pointer; border: none;
    box-shadow: 0 2px 8px rgba(59, 130, 246, 0.3);
}

/* ═══════════════════════════════════════════
   CALCULATE BUTTON
   ═══════════════════════════════════════════ */
.btn-calculate {
    display: block; width: 100%; padding: 0.85rem; margin-top: 0.5rem;
    font-size: 1rem; font-weight: 700; font-family: var(--font-sans);
    color: #fff; background: linear-gradient(135deg, var(--clr-accent), #2563eb);
    border: none; border-radius: var(--radius-sm); cursor: pointer;
    transition: transform var(--transition), box-shadow var(--transition);
    position: relative; overflow: hidden;
}
.btn-calculate::after {
    content: '';
    position: absolute; top: 0; left: -100%; width: 100%; height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.15), transparent);
    transition: left 0.5s;
}
.btn-calculate:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.35);
}
.btn-calculate:hover::after { left: 100%; }
.btn-calculate:active { transform: translateY(0); }

/* ═══════════════════════════════════════════
   ERROR MESSAGE
   ═══════════════════════════════════════════ */
.error-message {
    padding: 0.75rem 1rem; margin-bottom: 1rem;
    background: var(--clr-danger-glow); border: 1px solid var(--clr-danger);
    border-radius: var(--radius-sm); font-size: 0.85rem;
    color: var(--clr-danger); font-weight: 500;
}

/* ═══════════════════════════════════════════
   SUMMARY GRID
   ═══════════════════════════════════════════ */
.summary-grid {
    display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem;
    margin-bottom: 1.25rem;
}
@media (min-width: 480px) { .summary-grid { grid-template-columns: repeat(2, 1fr); } }
@media (min-width: 1024px) { .summary-grid { grid-template-columns: repeat(4, 1fr); } }

.summary-card {
    background: var(--clr-surface-2); border: 1px solid var(--clr-border);
    border-radius: var(--radius-sm); padding: 0.85rem 0.65rem; text-align: center;
    transition: transform var(--transition), border-color var(--transition), box-shadow var(--transition);
}
.summary-card:hover {
    transform: translateY(-2px);
    border-color: var(--clr-border-hover);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.2);
}

.summary-card--highlight {
    border-color: var(--clr-accent);
    background: var(--clr-accent-glow);
    box-shadow: var(--shadow-glow-blue);
}
.summary-card--highlight .summary-value { color: var(--clr-accent); }

.summary-label {
    display: block; font-size: 0.68rem; text-transform: uppercase;
    letter-spacing: 0.06em; color: var(--clr-text-muted); margin-bottom: 0.25rem;
}
.summary-value {
    display: block; font-size: 1.25rem; font-weight: 800;
    font-family: var(--font-mono); line-height: 1.2;
}
.summary-value--small { font-size: 0.95rem; }

/* ═══════════════════════════════════════════
   SLIVER ALERT
   ═══════════════════════════════════════════ */
.sliver-alert {
    display: flex; align-items: flex-start; gap: 0.5rem;
    padding: 0.75rem 1rem; margin-bottom: 1rem;
    background: var(--clr-warning-glow); border: 1px solid var(--clr-warning);
    border-radius: var(--radius-sm); font-size: 0.82rem;
    color: var(--clr-warning); font-weight: 500;
    animation: slideDown 0.3s ease-out;
}
.sliver-alert-icon { font-size: 1rem; flex-shrink: 0; }

/* ═══════════════════════════════════════════
   CHALK LINE INFO
   ═══════════════════════════════════════════ */
.chalk-line-info {
    background: var(--clr-accent-glow); border: 1px solid rgba(59, 130, 246, 0.3);
    border-radius: var(--radius-sm); padding: 1rem; margin-bottom: 1.25rem;
}
.chalk-line-info h3 { font-size: 0.9rem; margin-bottom: 0.4rem; color: var(--clr-text); }
.chalk-line-info p { font-size: 0.82rem; color: var(--clr-text-muted); line-height: 1.5; }

/* ═══════════════════════════════════════════
   EXPORT BUTTONS
   ═══════════════════════════════════════════ */
.export-row {
    display: flex; gap: 0.6rem; margin-bottom: 1.25rem;
}
.btn-export {
    flex: 1; padding: 0.6rem 0.75rem;
    font-size: 0.8rem; font-weight: 600; font-family: var(--font-sans);
    color: var(--clr-text-muted); background: var(--clr-surface-2);
    border: 1px solid var(--clr-border); border-radius: var(--radius-sm);
    cursor: pointer; transition: all var(--transition);
}
.btn-export:hover {
    color: var(--clr-text); border-color: var(--clr-accent);
    background: var(--clr-accent-glow);
}

/* ═══════════════════════════════════════════
   SVG GRID PREVIEW
   ═══════════════════════════════════════════ */
.grid-preview-container { margin-bottom: 0.5rem; }
.section-subtitle {
    font-size: 0.85rem; font-weight: 700; color: var(--clr-text-muted);
    text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: 0.75rem;
}
.grid-preview {
    min-height: 200px; overflow-x: auto; overflow-y: hidden;
    background: var(--clr-surface-2); border-radius: var(--radius-sm);
    border: 1px solid var(--clr-border); padding: 1rem;
}
.grid-preview svg { width: 100%; height: auto; display: block; }
.preview-placeholder {
    color: var(--clr-text-dim); text-align: center;
    padding: 3rem 1rem; font-size: 0.9rem;
}

/* ═══════════════════════════════════════════
   COLOR LEGEND
   ═══════════════════════════════════════════ */
.color-legend {
    display: flex; flex-wrap: wrap; gap: 1rem; justify-content: center;
    padding: 0.75rem 0; margin-top: 0.5rem;
    font-size: 0.72rem; color: var(--clr-text-muted);
}
.legend-item { display: flex; align-items: center; gap: 0.35rem; }
.legend-swatch {
    display: inline-block; width: 14px; height: 14px;
    border-radius: 3px; border: 1px solid var(--clr-border);
}
.legend-swatch--full { background: var(--clr-tile-full); }
.legend-swatch--cut { background: var(--clr-accent); }
.legend-swatch--grout { background: var(--clr-grout); }
.legend-swatch--chalk {
    background: transparent;
    border: 2px dashed var(--clr-chalk);
    width: 20px; height: 2px; border-radius: 0;
}

/* ═══════════════════════════════════════════
   HOW IT WORKS
   ═══════════════════════════════════════════ */
.how-it-works {
    margin-top: 2.5rem; padding: 0 0 1rem;
}
.section-title {
    font-size: 1.2rem; font-weight: 800; text-align: center;
    margin-bottom: 1.5rem; color: var(--clr-text);
    position: relative;
}
.section-title::after {
    content: '';
    display: block; width: 50px; height: 3px;
    background: var(--clr-accent); border-radius: 2px;
    margin: 0.6rem auto 0;
}
.how-grid {
    display: grid; gap: 1rem;
    grid-template-columns: 1fr;
}
@media (min-width: 480px) { .how-grid { grid-template-columns: 1fr 1fr; } }
@media (min-width: 768px) { .how-grid { grid-template-columns: repeat(4, 1fr); } }

.how-card {
    background: var(--clr-surface); border: 1px solid var(--clr-border);
    border-radius: var(--radius); padding: 1.25rem;
    text-align: center; transition: transform var(--transition), border-color var(--transition);
}
.how-card:hover { transform: translateY(-3px); border-color: var(--clr-accent); }
.how-icon { font-size: 1.75rem; display: block; margin-bottom: 0.6rem; }
.how-card h3 {
    font-size: 0.88rem; font-weight: 700; margin-bottom: 0.4rem;
    color: var(--clr-text);
}
.how-card p { font-size: 0.78rem; color: var(--clr-text-muted); line-height: 1.5; }

/* ═══════════════════════════════════════════
   FOOTER
   ═══════════════════════════════════════════ */
.site-footer {
    text-align: center; padding: 2rem 1rem; margin-top: 2.5rem;
    border-top: 1px solid var(--clr-border);
}
.footer-privacy {
    font-size: 0.82rem; color: var(--clr-accent); font-weight: 500;
    margin-bottom: 0.4rem;
}
.footer-disclaimer {
    font-size: 0.75rem; color: var(--clr-text-dim); margin-bottom: 0.6rem;
    font-style: italic;
}
.footer-copyright {
    font-size: 0.8rem; color: var(--clr-text-muted);
}

/* ═══════════════════════════════════════════
   TOAST NOTIFICATION
   ═══════════════════════════════════════════ */
.toast {
    position: fixed; bottom: -60px; left: 50%;
    transform: translateX(-50%); z-index: 1000;
    padding: 0.75rem 1.5rem; background: var(--clr-surface-3);
    border: 1px solid var(--clr-accent); border-radius: var(--radius);
    box-shadow: var(--shadow-glow-blue);
    font-size: 0.85rem; font-weight: 600; color: var(--clr-text);
    transition: bottom var(--transition-bounce);
    white-space: nowrap;
}
.toast.show { bottom: 2rem; }

/* ═══════════════════════════════════════════
   SVG TOOLTIP
   ═══════════════════════════════════════════ */
.svg-tooltip {
    position: fixed; z-index: 1100;
    padding: 0.5rem 0.75rem;
    background: var(--clr-surface-3); border: 1px solid var(--clr-accent);
    border-radius: var(--radius-sm); box-shadow: var(--shadow);
    font-size: 0.78rem; font-family: var(--font-mono);
    color: var(--clr-text); pointer-events: none;
    white-space: nowrap; max-width: 280px;
}
.svg-tooltip .tt-label { font-weight: 700; color: var(--clr-accent); }
.svg-tooltip .tt-dim { font-weight: 500; color: var(--clr-text-muted); }

/* ═══════════════════════════════════════════
   UTILITY CLASSES
   ═══════════════════════════════════════════ */
.hidden { display: none !important; }

/* ═══════════════════════════════════════════
   ANIMATIONS
   ═══════════════════════════════════════════ */
@keyframes slideDown {
    from { opacity: 0; transform: translateY(-8px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(12px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes tileSlideIn {
    from { opacity: 0; transform: scale(0.85); }
    to { opacity: 1; transform: scale(1); }
}

/* Staggered animation for SVG tiles */
.grid-preview svg rect.tile-animated {
    animation: tileSlideIn 0.3s ease-out both;
}

/* Summary card entrance */
.summary-card {
    animation: fadeInUp 0.3s ease-out both;
}
.summary-card:nth-child(1) { animation-delay: 0ms; }
.summary-card:nth-child(2) { animation-delay: 50ms; }
.summary-card:nth-child(3) { animation-delay: 100ms; }
.summary-card:nth-child(4) { animation-delay: 150ms; }
.summary-card:nth-child(5) { animation-delay: 200ms; }
.summary-card:nth-child(6) { animation-delay: 250ms; }
.summary-card:nth-child(7) { animation-delay: 300ms; }
.summary-card:nth-child(8) { animation-delay: 350ms; }

/* How-card entrance */
.how-card {
    animation: fadeInUp 0.4s ease-out both;
}
.how-card:nth-child(1) { animation-delay: 0ms; }
.how-card:nth-child(2) { animation-delay: 80ms; }
.how-card:nth-child(3) { animation-delay: 160ms; }
.how-card:nth-child(4) { animation-delay: 240ms; }

/* ═══════════════════════════════════════════
   RESPONSIVE
   ═══════════════════════════════════════════ */
@media (max-width: 479px) {
    .brand-name { font-size: 1.4rem; }
    .brand-icon { font-size: 1.5rem; }
    .panel { padding: 1.15rem; }
    .input-row { flex-direction: column; gap: 0; }
    .input-group--unit { max-width: none; }
    .preset-row { gap: 0.3rem; }
    .btn-preset { padding: 0.25rem 0.45rem; font-size: 0.68rem; }
    .summary-value { font-size: 1.1rem; }
    .summary-value--small { font-size: 0.82rem; }
    .toggle-row { flex-direction: column; align-items: flex-start; gap: 0.4rem; }
}

@media (min-width: 768px) {
    .brand-name { font-size: 2rem; }
    .site-header { padding: 3rem 1rem 2rem; }
    .summary-grid { grid-template-columns: repeat(4, 1fr); }
}

/* ═══════════════ AFFILIATE & SEO ═══════════════ */
.seo-card {
    background: var(--clr-surface);
    border: 1px solid var(--clr-border);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin: 2rem 0;
}
.seo-card h2 {
    color: var(--clr-text);
    margin-bottom: 0.5rem;
    font-size: 1.25rem;
}
.seo-card p {
    color: var(--clr-text-muted);
    line-height: 1.6;
}
.affiliate-gear a {
    color: var(--clr-accent);
    font-weight: 600;
    text-decoration: none;
}
.affiliate-gear a:hover {
    color: var(--clr-text);
    text-decoration: underline;
}