/* ============================================================
   OptiSolve AI — Dark Design System (Inverted)
   Palette: Dark backgrounds + light text + single accent
   Typography: Inter, tight headings, relaxed body
   Contrast: WCAG AA+ throughout
   ============================================================ */

:root {
    /* Neutrals — dark base */
    --black:  #09090b;
    --gray-9: #0f0f12;
    --gray-8: #18181b;
    --gray-7: #1e1e22;
    --gray-6: #27272a;
    --gray-5: #3f3f46;
    --gray-4: #52525b;
    --gray-3: #71717a;
    --gray-2: #a1a1aa;
    --gray-1: #d4d4d8;
    --white:  #f4f4f5;
    --pure-white: #fafafa;

    /* Single accent — muted indigo */
    --accent: #818cf8;
    --accent-bright: #a5b4fc;
    --accent-dim: #4f46e5;
    --accent-subtle: rgba(129, 140, 248, 0.08);
    --accent-glow: rgba(129, 140, 248, 0.15);

    /* Semantic */
    --success: #4ade80;
    --success-bg: rgba(74, 222, 128, 0.08);
    --success-border: rgba(74, 222, 128, 0.2);
    --error: #f87171;
    --error-bg: rgba(248, 113, 113, 0.08);
    --error-border: rgba(248, 113, 113, 0.2);

    /* Surfaces */
    --surface-0: #09090b;          /* page bg */
    --surface-1: #111114;          /* raised cards */
    --surface-2: #18181b;          /* higher elevation */
    --surface-3: #1e1e22;          /* hover states */
    --border: rgba(255,255,255,0.06);
    --border-hover: rgba(255,255,255,0.12);

    /* Type scale */
    --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
    --leading-tight: 1.15;
    --leading-snug: 1.35;
    --leading-relaxed: 1.65;
    --tracking-tight: -0.025em;
    --tracking-normal: 0;
    --tracking-wide: 0.05em;

    /* Text colors */
    --text-primary: #f4f4f5;
    --text-secondary: #a1a1aa;
    --text-muted: #71717a;
    --text-faint: #52525b;
}

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

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

body {
    font-family: var(--font);
    font-size: 16px;
    line-height: var(--leading-relaxed);
    color: var(--text-secondary);
    background: var(--surface-0);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

::selection { background: var(--accent-glow); color: var(--pure-white); }
a { color: inherit; text-decoration: none; }
img, svg { display: block; max-width: 100%; }
button { font-family: inherit; cursor: pointer; }

/* --- Typography --- */
h1, h2, h3 {
    color: var(--text-primary);
    letter-spacing: var(--tracking-tight);
    line-height: var(--leading-tight);
}
h1 { font-size: clamp(2rem, 5vw, 3.5rem); font-weight: 700; }
h2 { font-size: clamp(1.5rem, 3vw, 2.25rem); font-weight: 700; }
h3 { font-size: 1.125rem; font-weight: 600; }

/* --- Navbar --- */
.navbar {
    position: fixed;
    top: 0; left: 0; right: 0;
    z-index: 100;
    background: rgba(9,9,11,0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    height: 60px;
}
.navbar-inner {
    max-width: 1120px;
    margin: 0 auto;
    padding: 0 24px;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}
.nav-logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: var(--tracking-tight);
}
.nav-logo .mark {
    color: var(--accent);
}
.nav-logo .logo-icon {
    color: var(--accent);
    flex-shrink: 0;
}
.nav-links {
    display: flex;
    align-items: center;
    gap: 32px;
    list-style: none;
}
.nav-links a {
    font-size: 0.875rem;
    font-weight: 450;
    color: var(--text-muted);
    transition: color 0.2s;
}
.nav-links a:hover { color: var(--text-primary); }
.nav-spacer { height: 60px; }

/* Mobile nav */
.nav-mobile-btn {
    display: none;
    background: none;
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 6px;
    color: var(--text-secondary);
}
.nav-mobile-menu {
    display: none;
    position: absolute;
    top: 60px; left: 0; right: 0;
    background: var(--surface-1);
    border-bottom: 1px solid var(--border);
    padding: 16px 24px;
    flex-direction: column;
    gap: 12px;
}
.nav-mobile-menu.open { display: flex; }
.nav-mobile-menu a { font-size: 0.9rem; color: var(--text-secondary); font-weight: 450; }

@media (max-width: 768px) {
    .nav-links { display: none; }
    .nav-mobile-btn { display: block; }
}

/* --- Buttons --- */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-weight: 550;
    font-size: 0.875rem;
    border-radius: 8px;
    border: none;
    cursor: pointer;
    transition: all 0.15s ease;
    text-decoration: none;
    line-height: 1;
}
.btn:hover { transform: translateY(-1px); }
.btn:active { transform: translateY(0); }

.btn-primary {
    background: var(--pure-white);
    color: var(--black);
    padding: 10px 20px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.3), 0 0 0 1px rgba(255,255,255,0.06);
}
.btn-primary:hover {
    background: #fff;
    box-shadow: 0 4px 20px rgba(255,255,255,0.12), 0 0 0 1px rgba(255,255,255,0.1);
}

.btn-lg {
    padding: 14px 28px;
    font-size: 0.95rem;
    border-radius: 10px;
}

.btn-hero-primary {
    background: var(--pure-white);
    color: var(--black);
    padding: 16px 32px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 10px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.3), 0 0 0 1px rgba(255,255,255,0.08);
}
.btn-hero-primary:hover {
    box-shadow: 0 8px 40px rgba(255,255,255,0.15), 0 0 0 1px rgba(255,255,255,0.12);
    background: #fff;
}

.btn-hero-secondary {
    background: transparent;
    color: var(--text-secondary);
    padding: 16px 32px;
    font-size: 1rem;
    font-weight: 450;
    border: 1px solid var(--border-hover);
    border-radius: 10px;
    box-shadow: 0 1px 4px rgba(0,0,0,0.2);
}
.btn-hero-secondary:hover {
    background: rgba(255,255,255,0.04);
    color: var(--text-primary);
    border-color: rgba(255,255,255,0.2);
    box-shadow: 0 4px 20px rgba(0,0,0,0.3);
}

.btn-solve {
    width: 100%;
    justify-content: center;
    padding: 16px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 12px;
    background: var(--accent-dim);
    color: var(--pure-white);
    margin-bottom: 32px;
    box-shadow: 0 2px 12px rgba(79,70,229,0.25), 0 0 0 1px rgba(79,70,229,0.15);
}
.btn-solve:hover:not(:disabled) {
    background: #5b52f0;
    box-shadow: 0 8px 32px rgba(79,70,229,0.4), 0 0 0 1px rgba(79,70,229,0.3);
}
.btn-solve:disabled {
    background: var(--surface-2);
    color: var(--text-faint);
    cursor: not-allowed;
    transform: none !important;
    box-shadow: none !important;
}

.btn-full { width: 100%; justify-content: center; }

/* --- Hero --- */
.hero {
    background: var(--surface-0);
    position: relative;
    overflow: hidden;
    padding: 96px 24px 112px;
    text-align: center;
}
.hero::before {
    content: '';
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse at 30% 20%, rgba(129,140,248,0.07) 0%, transparent 60%),
        radial-gradient(ellipse at 70% 80%, rgba(129,140,248,0.04) 0%, transparent 60%);
    pointer-events: none;
}
.hero-inner {
    max-width: 720px;
    margin: 0 auto;
    position: relative;
    z-index: 1;
}
.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 6px 14px;
    border-radius: 100px;
    background: rgba(255,255,255,0.04);
    border: 1px solid var(--border);
    color: var(--text-muted);
    font-size: 0.8rem;
    font-weight: 450;
    margin-bottom: 32px;
    letter-spacing: var(--tracking-wide);
}
.pulse-dot {
    width: 6px; height: 6px;
    background: var(--success);
    border-radius: 50%;
    animation: pulse 2.5s ease-in-out infinite;
}
.hero h1 {
    color: var(--text-primary);
    margin-bottom: 20px;
    font-weight: 700;
}
.hero h1 .dim {
    color: var(--text-muted);
}
.hero-sub {
    font-size: 1.1rem;
    color: var(--text-muted);
    max-width: 540px;
    margin: 0 auto 40px;
    line-height: var(--leading-relaxed);
    font-weight: 380;
}
.hero-buttons {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    flex-wrap: wrap;
}
.hero-wave {
    position: absolute;
    bottom: -1px; left: 0; right: 0;
    line-height: 0;
}
.hero-wave svg { width: 100%; height: 48px; display: block; }
.hero-wave svg path { fill: var(--surface-1); }

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.4; }
}

/* --- Sections --- */
.section { padding: 80px 24px; background: var(--surface-1); }
.section-alt { background: var(--surface-0); }
.section-inner { max-width: 1040px; margin: 0 auto; }

.section-header { text-align: center; margin-bottom: 56px; }
.section-label {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--accent);
    margin-bottom: 8px;
}
.section-title { color: var(--text-primary); }

/* --- Steps --- */
.steps-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 40px;
}
@media (max-width: 768px) { .steps-grid { grid-template-columns: 1fr; gap: 36px; } }

.step { text-align: center; }
.step-number {
    width: 56px; height: 56px;
    margin: 0 auto 20px;
    border-radius: 14px;
    background: var(--accent-dim);
    color: var(--pure-white);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    font-weight: 700;
    transition: transform 0.2s;
}
.step:hover .step-number { transform: scale(1.06); }
.step h3 { margin-bottom: 8px; color: var(--text-primary); }
.step p { font-size: 0.9rem; color: var(--text-muted); max-width: 300px; margin: 0 auto; }

/* --- Features --- */
.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}
@media (max-width: 900px) { .features-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 600px) { .features-grid { grid-template-columns: 1fr; } }

.feature-card {
    background: var(--surface-1);
    border-radius: 14px;
    padding: 28px;
    border: 1px solid var(--border);
    transition: border-color 0.2s, box-shadow 0.2s;
}
.feature-card:hover {
    border-color: var(--border-hover);
    box-shadow: 0 4px 24px rgba(0,0,0,0.2);
}
.feature-icon {
    width: 44px; height: 44px;
    border-radius: 10px;
    background: var(--surface-2);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    margin-bottom: 16px;
}
.feature-card h3 { margin-bottom: 6px; color: var(--text-primary); }
.feature-card p { font-size: 0.85rem; color: var(--text-muted); line-height: var(--leading-relaxed); }

/* --- Tech Stack --- */
.tech-grid {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 12px;
}
.tech-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 20px;
    background: var(--surface-2);
    border-radius: 12px;
    border: 1px solid var(--border);
    transition: box-shadow 0.2s, border-color 0.2s;
}
.tech-item:hover {
    box-shadow: 0 2px 16px rgba(0,0,0,0.2);
    border-color: var(--border-hover);
}
.tech-emoji { font-size: 1.25rem; }
.tech-icon { color: var(--accent); flex-shrink: 0; }
.tech-item strong { font-size: 0.85rem; color: var(--text-primary); display: block; }
.tech-item small { font-size: 0.7rem; color: var(--text-muted); }

/* --- CTA Banner --- */
.cta-banner {
    max-width: 840px;
    margin: 0 auto;
    background: var(--surface-2);
    border-radius: 20px;
    padding: 64px 40px;
    text-align: center;
    position: relative;
    overflow: hidden;
    border: 1px solid var(--border);
}
.cta-banner::before {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(ellipse at 50% 0%, rgba(129,140,248,0.08) 0%, transparent 70%);
    pointer-events: none;
}
.cta-banner h2 { color: var(--text-primary); margin-bottom: 8px; position: relative; z-index: 1; }
.cta-banner p { color: var(--text-muted); font-size: 1rem; margin-bottom: 28px; position: relative; z-index: 1; }

/* --- Footer --- */
.footer {
    border-top: 1px solid var(--border);
    padding: 40px 24px;
    margin-top: 0;
    background: var(--surface-0);
}
.footer-inner {
    max-width: 1040px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 20px;
}
.footer-badges { display: flex; flex-wrap: wrap; gap: 6px; }
.footer-badge {
    padding: 4px 10px;
    background: var(--surface-2);
    border-radius: 6px;
    font-size: 0.7rem;
    font-weight: 500;
    color: var(--text-muted);
}
.footer-credit { font-size: 0.8rem; color: var(--text-faint); }
@media (max-width: 768px) {
    .footer-inner { flex-direction: column; text-align: center; }
}

/* --- App Page --- */
.app-container { max-width: 760px; margin: 0 auto; padding: 48px 24px; }

.card {
    background: var(--surface-1);
    border-radius: 14px;
    border: 1px solid var(--border);
    padding: 24px;
    margin-bottom: 20px;
}
.card-title {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 16px;
}
.card-title svg { color: var(--text-muted); }

.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
@media (max-width: 600px) { .form-grid { grid-template-columns: 1fr; } }

.form-label {
    display: block;
    font-size: 0.8rem;
    font-weight: 550;
    color: var(--text-secondary);
    margin-bottom: 6px;
}
.form-label .hint { font-weight: 400; color: var(--text-faint); }

.form-input {
    width: 100%;
    padding: 10px 14px;
    border-radius: 10px;
    border: 1px solid var(--border);
    font-size: 0.875rem;
    font-family: inherit;
    outline: none;
    transition: border-color 0.15s, box-shadow 0.15s;
    background: var(--surface-0);
    color: var(--text-primary);
}
.form-input:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-subtle);
}
.form-input::placeholder { color: var(--text-faint); }

.server-key-badge {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 4px 10px;
    background: var(--success-bg);
    color: var(--success);
    font-size: 0.7rem;
    font-weight: 550;
    border-radius: 6px;
    border: 1px solid var(--success-border);
    margin-left: auto;
}
.server-key-badge::before {
    content: '';
    width: 5px; height: 5px;
    background: var(--success);
    border-radius: 50%;
}

/* Upload zone */
.upload-zone {
    border: 1.5px dashed rgba(255,255,255,0.1);
    border-radius: 14px;
    padding: 48px 24px;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s;
    margin-bottom: 20px;
    background: var(--surface-1);
}
.upload-zone:hover, .upload-zone.drag-over {
    border-color: var(--accent);
    background: var(--surface-2);
}
.upload-icon { font-size: 2rem; margin-bottom: 12px; opacity: 0.5; }
.upload-title { font-size: 0.95rem; font-weight: 600; color: var(--text-primary); margin-bottom: 4px; }
.upload-sub { font-size: 0.85rem; color: var(--text-muted); margin-bottom: 12px; }
.upload-formats { font-size: 0.7rem; color: var(--text-faint); letter-spacing: var(--tracking-wide); }

.file-preview { display: none; align-items: center; justify-content: center; gap: 16px; }
.file-preview.visible { display: flex; }
.file-preview-icon {
    width: 44px; height: 44px;
    border-radius: 10px;
    background: var(--surface-2);
    display: flex; align-items: center; justify-content: center;
    font-size: 1.1rem;
}
.file-preview-name { font-weight: 600; font-size: 0.85rem; color: var(--text-primary); }
.file-preview-meta { font-size: 0.7rem; color: var(--text-muted); }
.file-remove {
    background: none; border: none; padding: 8px; border-radius: 8px;
    color: var(--text-faint); transition: all 0.15s;
}
.file-remove:hover { background: var(--error-bg); color: var(--error); }

/* Progress */
.progress-card { margin-bottom: 24px; }
.progress-header { display: flex; align-items: center; gap: 12px; margin-bottom: 20px; }
.progress-header p { font-weight: 600; color: var(--text-primary); font-size: 0.9rem; }
.progress-step { display: flex; align-items: center; gap: 12px; padding: 6px 0; }
.progress-step span { font-size: 0.85rem; color: var(--text-secondary); }

.spinner {
    width: 18px; height: 18px;
    border: 2px solid var(--surface-3);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 0.7s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

.step-icon {
    width: 26px; height: 26px;
    border-radius: 50%;
    display: flex; align-items: center; justify-content: center;
    font-size: 11px; font-weight: 700;
    flex-shrink: 0;
    transition: all 0.2s;
}
.step-pending { background: var(--surface-2); color: var(--text-faint); }
.step-active { background: var(--accent-dim); color: var(--pure-white); animation: pulse-step 1.5s ease-in-out infinite; }
.step-done { background: var(--success); color: var(--black); }
@keyframes pulse-step {
    0%, 100% { box-shadow: 0 0 0 0 rgba(79,70,229,0.4); }
    50% { box-shadow: 0 0 0 6px rgba(79,70,229,0); }
}

/* Results */
.result-banner {
    border-radius: 14px;
    padding: 24px;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 16px;
}
.result-banner.success { background: var(--success-bg); border: 1px solid var(--success-border); }
.result-banner.error { background: var(--error-bg); border: 1px solid var(--error-border); }
.result-banner .icon { font-size: 1.75rem; }
.result-banner h3 { font-size: 1.05rem; }
.result-banner.success h3 { color: var(--success); }
.result-banner.error h3 { color: var(--error); }
.result-banner p { font-size: 0.8rem; margin-top: 2px; }
.result-banner.success p { color: rgba(74,222,128,0.7); }
.result-banner.error p { color: rgba(248,113,113,0.7); }

.metrics-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; margin-bottom: 20px; }
@media (max-width: 600px) { .metrics-grid { grid-template-columns: repeat(2, 1fr); } }
.metric {
    background: var(--surface-1);
    border-radius: 12px;
    border: 1px solid var(--border);
    padding: 16px;
    text-align: center;
}
.metric-value { font-size: 1.5rem; font-weight: 700; color: var(--text-primary); }
.metric-label { font-size: 0.7rem; font-weight: 500; color: var(--text-muted); margin-top: 2px; text-transform: uppercase; letter-spacing: 0.04em; }

.objective-card { border-radius: 14px; border: 1px solid var(--border); padding: 24px; margin-bottom: 20px; background: var(--surface-1); }
.objective-label { font-size: 0.8rem; font-weight: 500; color: var(--text-muted); margin-bottom: 2px; }
.objective-value { font-size: 2.5rem; font-weight: 700; color: var(--text-primary); }

/* Tables */
.data-table { width: 100%; border-collapse: collapse; font-size: 0.85rem; }
.data-table th {
    text-align: left; padding: 10px 12px;
    font-size: 0.7rem; font-weight: 600;
    text-transform: uppercase; letter-spacing: 0.04em;
    color: var(--text-muted); border-bottom: 1px solid var(--border);
}
.data-table td { padding: 10px 12px; border-bottom: 1px solid var(--border); color: var(--text-secondary); }
.data-table tr:hover td { background: var(--surface-2); }
.data-table .mono { font-family: 'SF Mono', 'Fira Code', 'Consolas', monospace; font-size: 0.8rem; }
.data-table .val { font-weight: 700; color: var(--text-primary); text-align: right; }
.data-table .center { text-align: center; }

.type-badge {
    display: inline-block;
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 0.7rem;
    font-weight: 550;
}
.type-badge.integer { background: var(--accent-subtle); color: var(--accent); }
.type-badge.continuous { background: var(--surface-2); color: var(--text-muted); }
.bounds-text { font-family: 'SF Mono', 'Fira Code', monospace; font-size: 0.7rem; color: var(--text-faint); }

/* Collapsible */
details { margin-bottom: 20px; }
details summary {
    padding: 20px 24px;
    cursor: pointer;
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--text-secondary);
    border-radius: 14px;
    transition: background 0.15s;
    user-select: none;
}
details summary:hover { background: var(--surface-2); }
.detail-body { padding: 0 24px 20px; }
.code-block {
    background: var(--surface-0);
    border-radius: 10px;
    padding: 16px;
    font-size: 0.7rem;
    font-family: 'SF Mono', 'Fira Code', monospace;
    overflow-x: auto;
    color: var(--text-muted);
    white-space: pre-wrap;
    word-break: break-all;
    line-height: 1.5;
    border: 1px solid var(--border);
}

/* Error card */
.error-card {
    background: var(--error-bg);
    border: 1px solid var(--error-border);
    border-radius: 14px;
    padding: 20px;
    margin-bottom: 20px;
    display: flex;
    align-items: flex-start;
    gap: 12px;
}
.error-card .error-icon { font-size: 1.1rem; flex-shrink: 0; margin-top: 2px; }
.error-card .error-icon-svg { flex-shrink: 0; margin-top: 2px; color: var(--error); }
.error-card h3 { font-weight: 600; color: var(--error); font-size: 0.9rem; margin-bottom: 2px; }
.error-card p { font-size: 0.8rem; color: rgba(248,113,113,0.7); }

/* === Formulation Equations === */
.eq-section { padding: 4px 0; }
.eq-label {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 8px;
}
.eq-expr {
    font-family: 'SF Mono', 'Fira Code', 'Consolas', monospace;
    font-size: 1.05rem;
    color: var(--text-primary);
    padding: 8px 0;
    line-height: 1.6;
}
.eq-var {
    color: var(--accent-bright);
    font-weight: 600;
}
.eq-op {
    color: var(--text-muted);
    font-weight: 400;
}
.eq-constraint {
    font-family: 'SF Mono', 'Fira Code', 'Consolas', monospace;
    font-size: 0.85rem;
    color: var(--text-secondary);
    padding: 6px 0 6px 16px;
    border-left: 2px solid var(--border-hover);
    margin-bottom: 2px;
    line-height: 1.5;
}
.eq-bound {
    font-family: 'SF Mono', 'Fira Code', 'Consolas', monospace;
    font-size: 0.8rem;
    color: var(--text-muted);
    padding: 3px 0 3px 16px;
}
.eq-int-badge {
    display: inline-block;
    padding: 1px 6px;
    border-radius: 4px;
    font-size: 0.6rem;
    font-weight: 600;
    background: var(--accent-subtle);
    color: var(--accent);
    margin-left: 6px;
    vertical-align: middle;
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

/* === Constraint Grid === */
.zero-cell { color: var(--text-faint) !important; opacity: 0.4; }
.constraint-label { font-weight: 600; color: var(--text-muted); }

/* === Sensitivity Badges === */
.binding-badge {
    display: inline-block;
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 0.65rem;
    font-weight: 600;
    background: var(--accent-subtle);
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 0.03em;
}
.nonbinding-badge {
    display: inline-block;
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 0.65rem;
    font-weight: 600;
    background: var(--surface-2);
    color: var(--text-faint);
    text-transform: uppercase;
    letter-spacing: 0.03em;
}

/* === Sensitivity Note === */
.sensitivity-note {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-style: italic;
    padding: 12px 16px;
    background: var(--surface-0);
    border-radius: 8px;
    border: 1px solid var(--border);
}

/* === Solver Info === */
.info-label { font-size: 0.75rem; color: var(--text-muted); margin-bottom: 2px; }
.info-value { font-weight: 600; font-size: 0.9rem; color: var(--text-primary); }

/* Utility */
.hidden { display: none !important; }