:root {
  --bg: #f8fafc;
  --card: #ffffff;
  --fg: #1e293b;
  --muted: #64748b;
  --border: #e2e8f0;
  --primary: #0066FF;
  --primary-dark: #0052cc;
  --info-bg: #eff6ff;
  --success: #10b981;
  --warn: #f59e0b;
  --danger: #dc2626;
}
[data-theme="dark"] {
  --bg: #0f172a;
  --card: #1e293b;
  --fg: #e2e8f0;
  --muted: #94a3b8;
  --border: #334155;
  --info-bg: #1e3a5f;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
[hidden] { display: none !important; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
  background: var(--bg);
  color: var(--fg);
  overflow-x: hidden;
  transition: background 0.2s, color 0.2s;
}

#app { min-height: 100vh; }
.screen { display: none; min-height: 100vh; flex-direction: column; }
.screen.active { display: flex; }

.app-header {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: #fff;
  padding: 14px 16px;
  display: flex;
  align-items: center;
  gap: 10px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
}
.app-header .title { font-size: 18px; font-weight: 600; flex: 1; }
.header-btn {
  background: rgba(255,255,255,0.15);
  color: #fff;
  border: none;
  width: 36px; height: 36px;
  border-radius: 8px;
  font-size: 18px;
  cursor: pointer;
}
.header-btn:hover { background: rgba(255,255,255,0.25); }
.header-btn.back { font-weight: 700; }
.header-select {
  background: rgba(255,255,255,0.15);
  color: #fff;
  border: none;
  border-radius: 6px;
  padding: 6px 10px;
  font-size: 13px;
  font-weight: 600;
}
.header-select option { color: #333; }

.content { flex: 1; padding: 16px; overflow-y: auto; }

.btn {
  padding: 12px 18px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--fg);
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  font-family: inherit;
  transition: all 0.15s;
}
.btn:hover { filter: brightness(0.98); border-color: var(--primary); }
.btn-primary { background: var(--primary); color: #fff; border-color: var(--primary); }
.btn-primary:hover { background: var(--primary-dark); border-color: var(--primary-dark); }
.btn-secondary { background: var(--info-bg); color: var(--primary); border-color: var(--primary); }
.btn-danger { background: var(--danger); color: #fff; border-color: var(--danger); }
.btn-sm { padding: 6px 12px; font-size: 13px; }

.welcome-card {
  background: linear-gradient(135deg, var(--info-bg) 0%, #dbeafe 100%);
  padding: 20px;
  border-radius: 12px;
  margin-bottom: 20px;
  text-align: center;
}
[data-theme="dark"] .welcome-card { background: linear-gradient(135deg, #1e3a5f 0%, #172554 100%); }
.welcome-label { font-size: 12px; color: var(--muted); text-transform: uppercase; letter-spacing: 0.5px; }
.welcome-name { font-size: 22px; font-weight: 700; color: var(--primary); margin: 4px 0; }
.welcome-meta { font-size: 12px; color: var(--muted); }

.home-actions { display: flex; flex-direction: column; gap: 10px; }

.section-title {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--muted);
  font-weight: 600;
  margin: 24px 0 8px;
}

/* PROBLEM LIST */
.problem-item {
  background: var(--card);
  padding: 14px;
  border-radius: 10px;
  border: 1px solid var(--border);
  margin-bottom: 8px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 12px;
}
.problem-item:hover { border-color: var(--primary); }
.method-badge {
  padding: 4px 10px;
  border-radius: 6px;
  font-size: 12px;
  font-weight: 700;
  flex-shrink: 0;
}
.method-5why { background: #fef3c7; color: #92400e; }
.method-ishikawa { background: #dbeafe; color: #1e40af; }
.method-a3 { background: #e0e7ff; color: #3730a3; }
.method-8d { background: #fce7f3; color: #9d174d; }
.method-pdca { background: #d1fae5; color: #065f46; }

.problem-item .info { flex: 1; min-width: 0; }
.problem-item .title { font-weight: 600; font-size: 14px; }
.problem-item .meta { font-size: 12px; color: var(--muted); margin-top: 2px; }
.status-badge {
  padding: 3px 8px;
  border-radius: 12px;
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
}
.status-open { background: #fee2e2; color: #991b1b; }
.status-in_progress { background: #fef3c7; color: #92400e; }
.status-verified { background: #dbeafe; color: #1e40af; }
.status-closed { background: #d1fae5; color: #065f46; }
.btn-delete {
  background: transparent;
  border: none;
  font-size: 18px;
  color: #cbd5e1;
  cursor: pointer;
  padding: 4px 8px;
  border-radius: 6px;
}
.btn-delete:hover { color: var(--danger); background: #fee2e2; }

/* FORM */
.form-group { margin-bottom: 14px; }
.form-group label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--fg);
  margin-bottom: 6px;
}
.form-group input, .form-group textarea, .form-group select {
  width: 100%;
  padding: 10px 12px;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  font-size: 15px;
  font-family: inherit;
  background: var(--card);
  color: var(--fg);
}
.form-group input:focus, .form-group textarea:focus { outline: none; border-color: var(--primary); }
.form-group textarea { resize: vertical; min-height: 60px; }
.form-group input:disabled { background: var(--bg); color: var(--muted); }

/* METHOD PICKER */
.method-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 10px;
}
.method-btn {
  background: var(--card);
  border: 2px solid var(--border);
  padding: 14px 10px;
  border-radius: 10px;
  cursor: pointer;
  text-align: center;
  font-family: inherit;
  color: var(--fg);
}
.method-btn:hover { border-color: var(--primary); transform: translateY(-2px); }
.method-btn.selected { border-color: var(--primary); background: var(--info-bg); }
.mb-icon { font-size: 24px; margin-bottom: 6px; font-weight: 700; }
.mb-title { font-weight: 700; font-size: 14px; color: var(--primary); }
.mb-desc { font-size: 11px; color: var(--muted); margin-top: 4px; line-height: 1.3; }

/* 5 WHY */
.why-row { display: flex; align-items: flex-start; gap: 8px; margin-bottom: 10px; }
.why-num {
  background: var(--primary);
  color: #fff;
  min-width: 30px;
  height: 30px;
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  flex-shrink: 0;
  margin-top: 4px;
}
.why-row textarea {
  flex: 1;
  min-height: 44px;
  font-size: 14px;
  padding: 8px 10px;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  background: var(--card);
  color: var(--fg);
  font-family: inherit;
}

/* 5 WHY TREE */
.tree-container {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px;
  margin: 16px 0;
}
.tree-title { font-size: 13px; font-weight: 700; color: var(--primary); margin-bottom: 12px; }
.wt-node {
  background: var(--info-bg);
  border-left: 4px solid var(--primary);
  border-radius: 6px;
  padding: 8px 12px;
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 13px;
}
.wt-node.wt-symptom { background: #fef3c7; border-left-color: var(--warn); }
.wt-num { background: var(--primary); color: #fff; width: 22px; height: 22px; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-weight: 700; font-size: 12px; flex-shrink: 0; }
.wt-arrow { text-align: center; font-size: 20px; color: var(--muted); margin: 4px 0; }
.wt-empty { color: var(--muted); font-size: 12px; font-style: italic; }

/* ISHIKAWA */
.ishikawa-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.ishikawa-cat {
  background: var(--card);
  padding: 10px;
  border-radius: 8px;
  border-left: 4px solid;
  border: 1px solid var(--border);
}
.ishikawa-cat.man { border-left: 4px solid #3b82f6; }
.ishikawa-cat.machine { border-left: 4px solid #8b5cf6; }
.ishikawa-cat.material { border-left: 4px solid #f59e0b; }
.ishikawa-cat.method { border-left: 4px solid #ef4444; }
.ishikawa-cat.measurement { border-left: 4px solid #10b981; }
.ishikawa-cat.environment { border-left: 4px solid #6366f1; }
.ishikawa-cat h4 { font-size: 13px; margin-bottom: 6px; }
.ishikawa-cat textarea { width: 100%; min-height: 100px; font-size: 13px; padding: 8px; border: 1px solid var(--border); border-radius: 6px; background: var(--card); color: var(--fg); font-family: inherit; }

/* FISHBONE SVG */
.fishbone-container {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px;
  margin-bottom: 16px;
  overflow-x: auto;
}
.fishbone-hint { font-size: 11px; color: var(--muted); text-align: center; margin-top: 6px; }

/* A3 */
.a3-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
@media (max-width: 700px) { .a3-grid { grid-template-columns: 1fr; } }
.a3-section {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px;
}
.a3-section h4 { font-size: 13px; color: var(--primary); margin-bottom: 4px; text-transform: uppercase; letter-spacing: 0.3px; }
.prompt-hint { font-size: 11px; color: var(--muted); font-style: italic; margin-bottom: 6px; line-height: 1.4; }
.a3-section textarea { width: 100%; padding: 8px; border: 1px solid var(--border); border-radius: 6px; background: var(--card); color: var(--fg); font-family: inherit; font-size: 13px; }

/* 8D */
.d8-progress {
  display: flex;
  gap: 4px;
  overflow-x: auto;
  padding: 8px 0;
  margin-bottom: 12px;
}
.d8-step {
  background: var(--border);
  color: var(--muted);
  padding: 6px 12px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 700;
  white-space: nowrap;
  cursor: pointer;
}
.d8-step.done { background: var(--success); color: #fff; }
.d-section {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px;
  margin-bottom: 10px;
}
.d-label {
  display: inline-block;
  background: var(--primary);
  color: #fff;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 12px;
  font-weight: 700;
  margin-bottom: 6px;
}
.d-section textarea { width: 100%; padding: 8px; border: 1px solid var(--border); border-radius: 6px; background: var(--card); color: var(--fg); font-family: inherit; font-size: 13px; }

/* PDCA LOOP */
.pdca-loop {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4px;
  max-width: 240px;
  margin: 0 auto 20px;
}
.pdca-quadrant {
  background: var(--card);
  border: 2px solid var(--border);
  padding: 20px;
  text-align: center;
  font-size: 28px;
  font-weight: 900;
  color: var(--muted);
  aspect-ratio: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}
.pdca-quadrant small { font-size: 11px; margin-top: 4px; font-weight: 600; }
.pdca-quadrant.plan { border-top-left-radius: 50% 50%; }
.pdca-quadrant.do { border-top-right-radius: 50% 50%; }
.pdca-quadrant.check { border-bottom-left-radius: 50% 50%; }
.pdca-quadrant.act { border-bottom-right-radius: 50% 50%; }
.pdca-quadrant.filled.plan { background: #ef4444; color: #fff; border-color: #ef4444; }
.pdca-quadrant.filled.do { background: #f59e0b; color: #fff; border-color: #f59e0b; }
.pdca-quadrant.filled.check { background: #3b82f6; color: #fff; border-color: #3b82f6; }
.pdca-quadrant.filled.act { background: #10b981; color: #fff; border-color: #10b981; }

/* INFO BOX + VALIDATION */
.info-box {
  background: var(--info-bg);
  border-left: 4px solid var(--primary);
  padding: 10px 12px;
  border-radius: 6px;
  font-size: 13px;
  color: var(--fg);
  margin-bottom: 12px;
  line-height: 1.5;
}
.validation-box {
  background: #fefce8;
  border: 1px solid #fde047;
  border-radius: 8px;
  padding: 12px;
  margin-top: 16px;
}
[data-theme="dark"] .validation-box { background: #422006; border-color: #a16207; }
.validation-box h4 { font-size: 13px; color: #a16207; margin-bottom: 6px; }
[data-theme="dark"] .validation-box h4 { color: #fde047; }
.validation-box ul { padding-left: 20px; font-size: 12px; color: var(--fg); }
.validation-box li { margin: 4px 0; }

/* CHEATSHEET */
.decision-tree {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px;
  margin-bottom: 20px;
}
.decision-tree h3 { font-size: 14px; margin-bottom: 10px; color: var(--primary); }
.dt-question { margin-bottom: 12px; font-size: 13px; }
.dt-answer { font-size: 13px; color: var(--muted); margin-left: 8px; margin-top: 2px; }
.dt-answer strong { color: var(--primary); }

.cheat-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px;
  margin-bottom: 10px;
}
.cc-header { display: flex; align-items: center; gap: 10px; margin-bottom: 6px; }
.cc-badge { padding: 4px 10px; border-radius: 6px; font-size: 12px; font-weight: 700; }
.cc-title { font-weight: 700; font-size: 15px; }
.cc-when { font-size: 13px; color: var(--muted); margin-bottom: 8px; font-style: italic; }
.cc-meta { display: flex; gap: 8px; margin-bottom: 10px; flex-wrap: wrap; }
.cc-tag { background: var(--border); padding: 3px 8px; border-radius: 12px; font-size: 11px; }
.cc-good, .cc-bad { font-size: 12px; margin-bottom: 8px; }
.cc-good ul, .cc-bad ul { padding-left: 20px; margin-top: 4px; }
.cc-good li, .cc-bad li { margin: 2px 0; }

/* TEMPLATES */
.filter-bar {
  display: flex;
  gap: 6px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}
.filter-chip {
  background: var(--card);
  border: 1px solid var(--border);
  padding: 6px 12px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  color: var(--fg);
}
.filter-chip.active { background: var(--primary); color: #fff; border-color: var(--primary); }

.template-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px;
  margin-bottom: 10px;
}
.tc-header { display: flex; align-items: center; gap: 10px; margin-bottom: 8px; }
.tc-badge { padding: 4px 10px; border-radius: 6px; font-size: 11px; font-weight: 700; }
.tc-title { font-weight: 700; font-size: 14px; }
.tc-desc { font-size: 13px; color: var(--fg); margin-bottom: 6px; line-height: 1.5; }
.tc-meta { font-size: 11px; color: var(--muted); margin-bottom: 10px; }

/* EDIT ACTIONS */
.edit-actions {
  display: flex;
  gap: 8px;
  margin-top: 20px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
  flex-wrap: wrap;
}
.edit-actions .btn { flex: 1; min-width: 100px; }

/* FOOTER */
.app-footer {
  background: var(--card);
  padding: 12px;
  text-align: center;
  border-top: 1px solid var(--border);
  font-size: 12px;
  color: var(--muted);
}
.app-footer a { color: var(--primary); text-decoration: none; }

/* MODAL */
.modal-overlay {
  position: fixed;
  top: 0; left: 0; width: 100%; height: 100%;
  background: rgba(0,0,0,0.5);
  z-index: 100;
  align-items: center;
  justify-content: center;
  padding: 20px;
}
.modal-overlay:not([hidden]) { display: flex; }
.modal {
  background: var(--card);
  border-radius: 12px;
  padding: 20px;
  max-width: 400px;
  width: 100%;
  color: var(--fg);
}
.modal h3 { font-weight: 700; margin-bottom: 8px; }
.modal p { font-size: 14px; color: var(--muted); margin-bottom: 16px; }
.modal-actions { display: flex; gap: 8px; justify-content: flex-end; }

/* TOAST */
.toast {
  position: fixed;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--fg);
  color: var(--bg);
  padding: 10px 18px;
  border-radius: 8px;
  z-index: 200;
  font-size: 14px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

/* HELP */
#help-body h2 { font-size: 18px; color: var(--primary); margin: 16px 0 8px; }
#help-body h3 { font-size: 15px; color: var(--fg); margin: 12px 0 6px; }
#help-body p { margin-bottom: 8px; font-size: 14px; line-height: 1.5; }
#help-body ol, #help-body ul { padding-left: 20px; margin-bottom: 8px; }
#help-body li { font-size: 14px; margin: 4px 0; line-height: 1.5; }

@media (max-width: 600px) {
  .ishikawa-grid { grid-template-columns: 1fr; }
  .method-grid { grid-template-columns: repeat(2, 1fr); }
}