/* ==========================================================================
   style.css
   Stile moderno, accademico e ad alta leggibilità per lo strumento didattico
   di Scomposizione dei Polinomi (Liceo).
   ========================================================================== */

:root {
  --bg-page: #f4f6fb;
  --bg-card: #ffffff;
  --bg-subtle: #eef2f9;
  --bg-accent-soft: #e8f0fe;
  --text-main: #1a2234;
  --text-secondary: #4a5568;
  --text-muted: #718096;
  --border-color: #dbe2ef;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --primary-light: #dbeafe;
  --rule1-color: #7c3aed; /* Viola: Raccoglimento Totale */
  --rule1-bg: #f3e8ff;
  --rule2-color: #0891b2; /* Ciano: Raccoglimento Parziale */
  --rule2-bg: #cffafe;
  --rule3-color: #d97706; /* Ambra: Prodotti Notevoli */
  --rule3-bg: #fef3c7;
  --rule4-color: #059669; /* Smeraldo: Regola di Ruffini */
  --rule4-bg: #d1fae5;
  --danger: #dc2626;
  --danger-bg: #fee2e2;
  --success: #16a34a;
  --success-bg: #dcfce7;
  --shadow-sm: 0 2px 6px rgba(15, 23, 42, 0.05);
  --shadow-md: 0 6px 18px rgba(15, 23, 42, 0.08);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
}

body.dark-mode {
  --bg-page: #0f172a;
  --bg-card: #1e293b;
  --bg-subtle: #334155;
  --bg-accent-soft: #1e3a5f;
  --text-main: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --border-color: #334155;
  --primary: #3b82f6;
  --primary-hover: #60a5fa;
  --primary-light: #1e3a8a;
  --rule1-color: #c084fc;
  --rule1-bg: #3b0764;
  --rule2-color: #22d3ee;
  --rule2-bg: #164e63;
  --rule3-color: #fbbf24;
  --rule3-bg: #451a03;
  --rule4-color: #34d399;
  --rule4-bg: #064e3b;
  --danger: #f87171;
  --danger-bg: #450a0a;
  --success: #4ade80;
  --success-bg: #052e16;
}

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--bg-page);
  color: var(--text-main);
  line-height: 1.6;
  padding-bottom: 4rem;
  transition: background-color 0.2s, color 0.2s;
}

/* Header */
.app-header {
  background: linear-gradient(135deg, #1e3a8a 0%, #2563eb 100%);
  color: #ffffff;
  padding: 1.75rem 1.5rem;
  box-shadow: var(--shadow-md);
}

.header-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.header-title h1 {
  font-size: 1.65rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 0.25rem;
}

.header-title p {
  font-size: 0.95rem;
  opacity: 0.9;
}

.header-actions {
  display: flex;
  gap: 0.6rem;
}

.btn-outline-light {
  background: rgba(255, 255, 255, 0.14);
  color: #ffffff;
  border: 1px solid rgba(255, 255, 255, 0.3);
  padding: 0.5rem 0.95rem;
  border-radius: var(--radius-sm);
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s;
}

.btn-outline-light:hover {
  background: rgba(255, 255, 255, 0.25);
}

/* Layout Principale */
.container {
  max-width: 1200px;
  margin: 1.5rem auto 0;
  padding: 0 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1.1rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border-color);
}

.card-header h2 {
  font-size: 1.2rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* Tabs Input Mode */
.mode-tabs {
  display: inline-flex;
  background: var(--bg-subtle);
  padding: 0.25rem;
  border-radius: var(--radius-sm);
  gap: 0.25rem;
}

.mode-tab {
  border: none;
  background: transparent;
  color: var(--text-secondary);
  padding: 0.45rem 0.95rem;
  border-radius: 6px;
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s;
}

.mode-tab.active {
  background: var(--bg-card);
  color: var(--primary);
  box-shadow: var(--shadow-sm);
}

/* Costruttore Visuale di Termini (Coefficienti e Potenze) */
.builder-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.quick-templates {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.45rem;
}

.quick-templates span {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-right: 0.25rem;
}

.chip-btn {
  background: var(--bg-subtle);
  color: var(--text-main);
  border: 1px solid var(--border-color);
  padding: 0.35rem 0.7rem;
  border-radius: 999px;
  font-size: 0.82rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s;
}

.chip-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
  background: var(--bg-accent-soft);
}

.terms-builder-grid {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem;
  background: var(--bg-subtle);
  border-radius: var(--radius-md);
  border: 1px dashed var(--border-color);
}

.term-box {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 0.65rem 0.8rem;
  display: flex;
  align-items: center;
  gap: 0.45rem;
  box-shadow: var(--shadow-sm);
  position: relative;
}

.term-sign-btn {
  width: 32px;
  height: 36px;
  border-radius: 6px;
  border: 1px solid var(--border-color);
  background: var(--bg-subtle);
  color: var(--text-main);
  font-size: 1.15rem;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
}

.term-sign-btn.neg {
  background: var(--danger-bg);
  color: var(--danger);
  border-color: var(--danger);
}

.term-sign-btn.pos {
  background: var(--success-bg);
  color: var(--success);
  border-color: var(--success);
}

.term-coeff-input {
  width: 64px;
  height: 36px;
  padding: 0 0.45rem;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  background: var(--bg-card);
  color: var(--text-main);
  font-size: 1rem;
  font-weight: 600;
  text-align: center;
}

.term-var-group {
  display: flex;
  align-items: flex-start;
}

.term-var-label {
  font-family: 'Cambria Math', 'Times New Roman', serif;
  font-style: italic;
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--primary);
  margin: 0 2px;
  line-height: 36px;
}

.term-exp-wrapper {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin-top: -4px;
}

.term-exp-label {
  font-size: 0.65rem;
  color: var(--text-muted);
  text-transform: uppercase;
  font-weight: 700;
}

.term-exp-input {
  width: 48px;
  height: 28px;
  padding: 0 0.25rem;
  border: 1px solid var(--border-color);
  border-radius: 5px;
  background: var(--bg-subtle);
  color: var(--text-main);
  font-size: 0.88rem;
  font-weight: 700;
  text-align: center;
}

.term-remove-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 1.1rem;
  cursor: pointer;
  padding: 0 0.2rem;
  line-height: 1;
}

.term-remove-btn:hover {
  color: var(--danger);
}

.btn-add-term {
  background: var(--bg-card);
  color: var(--primary);
  border: 2px dashed var(--primary);
  border-radius: var(--radius-sm);
  padding: 0.65rem 1rem;
  font-weight: 700;
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.15s;
}

.btn-add-term:hover {
  background: var(--primary-light);
}

/* Modalità Testo Libero */
.free-text-box {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.free-text-input-row {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.poly-text-input {
  flex: 1;
  min-width: 260px;
  padding: 0.75rem 1rem;
  font-size: 1.1rem;
  font-family: 'JetBrains Mono', monospace;
  border: 2px solid var(--border-color);
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  color: var(--text-main);
}

.poly-text-input:focus {
  outline: none;
  border-color: var(--primary);
}

.input-hint {
  font-size: 0.83rem;
  color: var(--text-muted);
}

/* Anteprima Polinomio & Bottone Scomponi */
.preview-bar {
  margin-top: 1.15rem;
  padding: 1rem 1.25rem;
  background: var(--bg-accent-soft);
  border: 1px solid var(--primary-light);
  border-radius: var(--radius-md);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.preview-math-area {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.preview-label {
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.preview-formula {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-main);
}

.btn-primary-solve {
  background: var(--primary);
  color: #ffffff;
  border: none;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.25);
  transition: background 0.15s, transform 0.1s;
}

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

/* Galleria Esempi Didattici */
.presets-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(235px, 1fr));
  gap: 0.65rem;
}

.preset-card {
  background: var(--bg-subtle);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 0.6rem 0.85rem;
  text-align: left;
  cursor: pointer;
  transition: all 0.15s;
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}

.preset-card:hover {
  border-color: var(--primary);
  background: var(--bg-accent-soft);
  transform: translateY(-1px);
}

.preset-tag {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--primary);
  letter-spacing: 0.03em;
}

.preset-math {
  font-size: 0.98rem;
  font-weight: 600;
  color: var(--text-main);
}

/* Gerarchia / Checklist delle 4 Regole */
.hierarchy-stepper {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 0.85rem;
}

.hierarchy-node {
  border: 1px solid var(--border-color);
  background: var(--bg-subtle);
  border-radius: var(--radius-sm);
  padding: 0.85rem 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  position: relative;
  transition: all 0.2s;
}

.hierarchy-node.applied {
  border-width: 2px;
  background: var(--bg-card);
  box-shadow: var(--shadow-sm);
}

.hierarchy-node.rule-1.applied { border-color: var(--rule1-color); }
.hierarchy-node.rule-2.applied { border-color: var(--rule2-color); }
.hierarchy-node.rule-3.applied { border-color: var(--rule3-color); }
.hierarchy-node.rule-4.applied { border-color: var(--rule4-color); }

.node-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.node-num {
  font-size: 0.75rem;
  font-weight: 800;
  text-transform: uppercase;
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
}

.rule-1 .node-num { background: var(--rule1-bg); color: var(--rule1-color); }
.rule-2 .node-num { background: var(--rule2-bg); color: var(--rule2-color); }
.rule-3 .node-num { background: var(--rule3-bg); color: var(--rule3-color); }
.rule-4 .node-num { background: var(--rule4-bg); color: var(--rule4-color); }

.node-status {
  font-size: 0.78rem;
  font-weight: 700;
}

.node-status.used { color: var(--success); }
.node-status.skipped { color: var(--text-muted); }

.node-title {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-main);
}

.node-desc {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

/* Passaggi di Scomposizione (Timeline) */
.steps-timeline {
  display: flex;
  flex-direction: column;
  gap: 1.15rem;
}

.step-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-left: 5px solid var(--primary);
  border-radius: var(--radius-md);
  padding: 1.25rem 1.4rem;
  box-shadow: var(--shadow-sm);
}

.step-card.rule-1 { border-left-color: var(--rule1-color); }
.step-card.rule-2 { border-left-color: var(--rule2-color); }
.step-card.rule-3 { border-left-color: var(--rule3-color); }
.step-card.rule-4 { border-left-color: var(--rule4-color); }

.step-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 0.85rem;
}

.step-badges {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.step-num-badge {
  background: var(--text-main);
  color: var(--bg-card);
  font-size: 0.76rem;
  font-weight: 800;
  padding: 0.2rem 0.55rem;
  border-radius: 6px;
}

.step-tech-badge {
  font-size: 0.82rem;
  font-weight: 700;
  padding: 0.2rem 0.65rem;
  border-radius: 6px;
}

.rule-1 .step-tech-badge { background: var(--rule1-bg); color: var(--rule1-color); }
.rule-2 .step-tech-badge { background: var(--rule2-bg); color: var(--rule2-color); }
.rule-3 .step-tech-badge { background: var(--rule3-bg); color: var(--rule3-color); }
.rule-4 .step-tech-badge { background: var(--rule4-bg); color: var(--rule4-color); }

.step-formula-pill {
  font-size: 0.85rem;
  background: var(--bg-subtle);
  padding: 0.25rem 0.65rem;
  border-radius: 6px;
  color: var(--text-secondary);
}

.step-body {
  font-size: 0.97rem;
  color: var(--text-main);
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}

.step-result-box {
  margin-top: 0.4rem;
  padding: 0.75rem 1rem;
  background: var(--bg-subtle);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.step-result-label {
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--text-secondary);
  text-transform: uppercase;
}

/* Tabella Grafica di Ruffini */
.ruffini-container {
  margin: 0.75rem 0;
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
  background: var(--bg-subtle);
  padding: 1rem 1.25rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
}

.ruffini-trials {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.trial-chip {
  font-size: 0.84rem;
  padding: 0.25rem 0.65rem;
  border-radius: 6px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
}

.trial-chip.success {
  background: var(--success-bg);
  border-color: var(--success);
  color: var(--success);
  font-weight: 700;
}

.ruffini-table-wrapper {
  overflow-x: auto;
}

.ruffini-grid {
  border-collapse: collapse;
  font-family: 'JetBrains Mono', monospace;
  font-size: 1rem;
  margin: 0.25rem 0;
}

.ruffini-grid td, .ruffini-grid th {
  padding: 0.45rem 0.9rem;
  text-align: center;
  min-width: 52px;
}

.ruffini-grid .power-header {
  font-size: 0.75rem;
  color: var(--text-muted);
  border-bottom: 1px dashed var(--border-color);
}

.ruffini-grid .col-left {
  border-right: 2.5px solid var(--text-main);
  font-weight: 700;
  color: var(--rule4-color);
}

.ruffini-grid .col-last {
  border-left: 2.5px solid var(--text-main);
}

.ruffini-grid .row-mid td {
  border-bottom: 2.5px solid var(--text-main);
  color: var(--primary);
}

.ruffini-grid .row-bot td {
  font-weight: 700;
}

.ruffini-grid .remainder-cell {
  background: var(--success-bg);
  color: var(--success);
  border-radius: 4px;
}

/* Box Approfondimento Delta Alternativo */
.delta-details {
  margin-top: 0.35rem;
  background: var(--bg-subtle);
  border-radius: var(--radius-sm);
  padding: 0.6rem 0.9rem;
  font-size: 0.88rem;
}

.delta-details summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--primary);
}

/* Banner Risultato Finale */
.final-result-banner {
  background: linear-gradient(135deg, var(--bg-accent-soft) 0%, var(--bg-card) 100%);
  border: 2px solid var(--primary);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
  box-shadow: var(--shadow-md);
}

.final-banner-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.final-label {
  font-size: 0.9rem;
  font-weight: 800;
  text-transform: uppercase;
  color: var(--primary);
  letter-spacing: 0.05em;
}

.final-equation {
  font-size: 1.45rem;
  font-weight: 800;
  padding: 0.75rem 1rem;
  background: var(--bg-card);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  overflow-x: auto;
}

/* Sezione Riepilogo Teorico Collapsible */
.theory-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(270px, 1fr));
  gap: 1rem;
  margin-top: 0.5rem;
}

.theory-block {
  background: var(--bg-subtle);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 1rem;
}

.theory-block h3 {
  font-size: 0.98rem;
  margin-bottom: 0.5rem;
  color: var(--primary);
}

.theory-block ul {
  padding-left: 1.15rem;
  font-size: 0.87rem;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

@media (max-width: 640px) {
  .preview-bar {
    flex-direction: column;
    align-items: stretch;
  }
  .btn-primary-solve {
    width: 100%;
  }
}