:root {
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-color: #fbbf24;
    --accent-hover: #f59e0b;
    --border-color: rgba(255, 255, 255, 0.1);
    --success: #22c55e;
    --error: #ef4444;
}

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

body {
    font-family: 'Outfit', sans-serif;
    background: var(--bg-color);
    color: var(--text-primary);
    min-height: 100vh;
    padding: 2rem;
}

#app-container {
    max-width: 1000px;
    margin: 0 auto;
}

header {
    margin-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1rem;
}

h1 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--accent-color);
}

.subtitle {
    color: var(--text-secondary);
}

main {
    display: grid;
    gap: 2rem;
}

.input-section {
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    display: grid;
    gap: 1.5rem;
}

h2 {
    font-size: 1.3rem;
    color: var(--accent-color);
    margin-bottom: -0.5rem;
}

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

label {
    font-weight: 500;
    color: var(--text-primary);
}

input[type="text"],
input[type="number"] {
    background: rgba(15, 23, 42, 0.6);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 0.75rem;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 1rem;
}

input[type="text"]:focus,
input[type="number"]:focus {
    outline: none;
    border-color: var(--accent-color);
}

select {
    appearance: none;
    background-color: rgba(15, 23, 42, 0.6);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 0.75rem;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 1rem;
    width: 100%;
    cursor: pointer;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%2394a3b8'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M19 9l-7 7-7-7'%3E%3C/path%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 1rem center;
    background-size: 1em;
}

select:focus {
    outline: none;
    border-color: var(--accent-color);
}

select option {
    background-color: #1e293b;
    color: var(--text-primary);
}

.help-text {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.btn {
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: all 0.2s;
    font-size: 1rem;
}

.btn.primary {
    background: var(--accent-color);
    color: #0f172a;
}

.btn.primary:hover {
    background: var(--accent-hover);
}

.btn.secondary {
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn.secondary:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--text-secondary);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

#results-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

#results-section.hidden {
    display: none;
}

.result-card {
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.result-card.full-width {
    grid-column: 1 / -1;
}

h3 {
    margin-bottom: 1rem;
    font-size: 1.1rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

h3 .math {
    text-transform: none;
    letter-spacing: normal;
}

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

.status-bar {
    grid-column: 1 / -1;
    padding: 1rem;
    border-radius: 8px;
    background: rgba(15, 23, 42, 0.6);
    border: 1px solid var(--border-color);
    font-weight: bold;
    font-size: 1.2rem;
    text-align: center;
}

.status-success {
    color: var(--success);
    border-color: var(--success);
    background: rgba(34, 197, 94, 0.1);
}

.status-error {
    color: var(--error);
    border-color: var(--error);
    background: rgba(239, 68, 68, 0.1);
}

/* Back link */
.back-link {
    display: inline-block;
    color: #fbbf24;
    text-decoration: none;
    font-size: 0.85rem;
    opacity: 0.7;
    transition: opacity 0.2s;
    margin-bottom: 8px;
}

.back-link:hover {
    opacity: 1;
}

.mapping-row {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.mapping-arrow {
    font-size: 1.5rem;
    color: var(--text-secondary);
}

.relation-eval {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 0.5rem;
    padding: 0.5rem;
    background: rgba(0, 0, 0, 0.2);
    border-radius: 6px;
}

.relation-eval span.eval-string {
    flex: 1;
}

.relation-eval span.eval-result {
    font-weight: bold;
}

.eval-pass {
    color: var(--success);
}

.eval-fail {
    color: var(--error);
}

/* Modal Styles */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.7);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 1;
    transition: opacity 0.2s ease;
}

.modal-overlay.hidden {
    opacity: 0;
    pointer-events: none;
}

.modal {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    width: 90%;
    max-width: 600px;
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.5);
    transform: translateY(0);
    transition: transform 0.2s ease;
}

.modal-overlay.hidden .modal {
    transform: translateY(20px);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h3 {
    margin: 0;
    color: var(--accent-color);
    text-transform: none;
    letter-spacing: normal;
}

.close-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    font-size: 1.5rem;
    cursor: pointer;
    transition: color 0.2s;
    line-height: 1;
}

.close-btn:hover {
    color: var(--text-primary);
}

.modal-body {
    padding: 1.5rem;
}

#theory-btn:hover {
    color: var(--text-primary) !important;
    border-color: var(--text-secondary) !important;
}

/* ─── General hidden utility ─────────────────────────────────────────────── */
.hidden {
    display: none !important;
}

/* ─── Mode tabs ──────────────────────────────────────────────────────────── */
.mode-tabs {
    display: flex;
    gap: 0.5rem;
    margin-top: 1rem;
}

.mode-tab {
    padding: 0.4rem 1.25rem;
    border-radius: 20px;
    border: 1px solid var(--border-color);
    background: transparent;
    color: var(--text-secondary);
    cursor: pointer;
    font-family: inherit;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.2s;
}

.mode-tab:hover {
    border-color: var(--accent-color);
    color: var(--text-primary);
}

.mode-tab.active {
    background: var(--accent-color);
    color: #0f172a;
    border-color: var(--accent-color);
    font-weight: 600;
}

/* ─── Representations mode results grid ──────────────────────────────────── */
#rep-results {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

#rep-results.hidden {
    display: none;
}

/* ─── Generator matrix blocks ────────────────────────────────────────────── */
.gen-matrix-block {
    background: rgba(0, 0, 0, 0.2);
    padding: 1rem 1.25rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    font-size: 1.05rem;
}

/* ─── Character table ────────────────────────────────────────────────────── */
.char-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.95rem;
    margin-top: 0.5rem;
}

.char-table th {
    color: var(--text-secondary);
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-weight: 600;
    padding: 0.4rem 0.75rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.char-table th.class-group-header {
    text-align: center;
}

.char-table td {
    padding: 0.4rem 0.75rem;
    border-bottom: 1px solid rgba(255,255,255,0.05);
    color: var(--text-primary);
}

/* === Accessibility === */
:focus-visible {
    outline: 3px solid var(--accent-color, #38bdf8);
    outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}