/* ==========================================================
   CUBELIB — Professional FMC Solver UI
   Clean, light-on-dark design with IBM Plex font system
   ========================================================== */

@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Sans:wght@400;500;600;700&family=IBM+Plex+Mono:wght@400;500;600&family=Nunito:wght@700;800;900&display=swap');

/* ── Tokens ── */
:root {
  --font-sans: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  --font-mono: 'IBM Plex Mono', 'Consolas', 'SF Mono', monospace;

  --white: #ffffff;
  --gray-50:  #f8fafc;
  --gray-100: #f1f5f9;
  --gray-200: #e2e8f0;
  --gray-300: #cbd5e1;
  --gray-400: #94a3b8;
  --gray-500: #64748b;
  --gray-600: #475569;
  --gray-700: #334155;
  --gray-800: #1e293b;
  --gray-900: #0f172a;
  --gray-950: #020617;

  --sky-50:  #f0f9ff;
  --sky-100: #e0f2fe;
  --sky-400: #38bdf8;
  --sky-500: #0ea5e9;
  --sky-600: #0284c7;
  --sky-700: #0369a1;

  --blue-500: #3b82f6;
  --violet-500: #8b5cf6;
  --red-500: #ef4444;
  --orange-500: #f97316;
  --amber-500: #eab308;
  --green-500: #22c55e;
  --teal-500: #14b8a6;
  --purple-500: #a855f7;

  --cube-W: #f0f0f0;
  --cube-Y: #facc15;
  --cube-R: #dc2626;
  --cube-O: #ea580c;
  --cube-B: #2563eb;
  --cube-G: #16a34a;

  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;

  --shadow-sm: 0 1px 2px rgba(0,0,0,.06);
  --shadow-md: 0 2px 8px rgba(0,0,0,.08);
  --shadow-lg: 0 8px 24px rgba(0,0,0,.12);
  --shadow-xl: 0 16px 48px rgba(0,0,0,.18);
}

/* ── Reset ── */
*,*::before,*::after{margin:0;padding:0;box-sizing:border-box}
html{font-size:15px;scroll-behavior:smooth;-webkit-text-size-adjust:100%}

body {
  font-family: var(--font-sans);
  background: var(--gray-50);
  color: var(--gray-900);
  min-height: 100vh;
  direction: ltr;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  letter-spacing: -0.01em;
}

::selection { background: rgba(14,165,233,.18); color: var(--gray-900); }
:focus-visible { outline: 2px solid var(--sky-500); outline-offset: 2px; }

/* ── Scrollbar ── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--gray-300); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--gray-400); }

/* ==========================================================
   TOP BAR
   ========================================================== */
.topbar {
  position: relative;
  z-index: 100;
  background: var(--white);
  border-bottom: 1px solid var(--gray-200);
  box-shadow: 0 1px 3px rgba(0,0,0,.04);
}

.topbar-inner {
  max-width: 1360px;
  margin: 0 auto;
  padding: 0 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 72px;
}

.brand-name {
  font-size: 3.2rem;
  font-weight: 800;
  color: var(--sky-600);
  letter-spacing: -0.02em;
  font-family: 'Nunito', var(--font-sans);
}


/* ==========================================================
   SHELL & LAYOUT
   ========================================================== */
.shell {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px 28px 40px;
}

@keyframes fadeUp { from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none} }

.content { min-width: 0; }

/* ==========================================================
   CARD
   ========================================================== */
.card {
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-xl);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.card-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  border-bottom: 1px solid var(--gray-100);
}
.card-head h2, .card-head h3 {
  font-size: 0.87rem;
  font-weight: 700;
  color: var(--gray-800);
  letter-spacing: -0.01em;
}
.card-body { padding: 20px; }


/* ==========================================================
   FORM ELEMENTS
   ========================================================== */
.field { margin-bottom: 16px; }
.field-label {
  display: block;
  font-size: 0.78rem; font-weight: 600;
  color: var(--gray-600);
  margin-bottom: 6px;
  letter-spacing: 0.01em;
}
.field-label-sm {
  display: block;
  font-size: 0.72rem; font-weight: 600;
  color: var(--gray-500);
  margin-bottom: 4px;
}
.field-row { display: flex; gap: 8px; align-items: flex-start; }
.field-row .input { flex: 1; }
textarea.input { resize: none; overflow: hidden; line-height: 1.5; font-size: .95rem; letter-spacing: .03em; padding-top: 8px; padding-bottom: 8px; box-sizing: border-box; }

.input {
  width: 100%;
  padding: 9px 12px;
  background: var(--white);
  border: 1px solid var(--gray-300);
  border-radius: var(--radius-md);
  font-family: var(--font-sans);
  font-size: 0.87rem;
  color: var(--gray-900);
  transition: border-color .15s, box-shadow .15s;
}
.input.mono { font-family: var(--font-mono); font-size: 0.85rem; }
.input::placeholder { color: var(--gray-400); }
.input:hover { border-color: var(--gray-400); }
.input:focus {
  outline: none;
  border-color: var(--sky-500);
  box-shadow: 0 0 0 3px rgba(14,165,233,.12);
}

select.input {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg width='10' height='6' viewBox='0 0 10 6' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M1 1l4 4 4-4' stroke='%2394a3b8' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 32px;
}

.hint {
  color: var(--gray-500);
  font-size: 0.82rem;
  margin-bottom: 14px;
  line-height: 1.5;
}

/* ==========================================================
   BUTTONS
   ========================================================== */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  gap: 6px;
  padding: 9px 18px;
  border: 1px solid var(--gray-300);
  border-radius: var(--radius-md);
  background: var(--white);
  font-family: var(--font-sans);
  font-size: 0.85rem; font-weight: 500;
  color: var(--gray-700);
  cursor: pointer;
  transition: all .12s ease;
  white-space: nowrap;
  user-select: none;
}
.btn:hover { background: var(--gray-50); border-color: var(--gray-400); }
.btn:active { transform: scale(.98); }
.btn:disabled { opacity: .4; cursor: not-allowed; }

.btn-primary {
  background: var(--sky-500);
  border-color: var(--sky-500);
  color: var(--white);
  font-weight: 600;
  box-shadow: 0 1px 3px rgba(14,165,233,.25);
}
.btn-primary:hover { background: var(--sky-600); border-color: var(--sky-600); }

.btn-ghost {
  background: transparent;
  border-color: transparent;
  color: var(--gray-600);
}
.btn-ghost:hover { background: var(--gray-100); color: var(--gray-800); border-color: transparent; }

.btn-lg { padding: 12px 28px; font-size: 0.93rem; width: 100%; border-radius: var(--radius-lg); font-weight: 600; }
.btn-sm { padding: 6px 12px; font-size: 0.78rem; }
.btn-xs { padding: 4px 10px; font-size: 0.73rem; }
.btn-icon { width: 40px; height: 40px; padding: 0; flex-shrink: 0; }
.scramble-gen-btn { display: flex; align-items: center; gap: 6px; padding: 6px 14px; font-size: .82rem; flex-shrink: 0; white-space: nowrap; }
.btn-block { width: 100%; }

.solve-buttons { display: flex; gap: 8px; }
.solve-buttons .btn-lg { flex: 1; }
.stop-btn {
  background: var(--red-500) !important;
  border-color: var(--red-500) !important;
  color: var(--white) !important;
  font-weight: 600;
}
.stop-btn:hover { opacity: 0.9; }

.spinner {
  display: inline-block; width: 14px; height: 14px;
  border: 2px solid rgba(255,255,255,.25);
  border-top-color: #fff;
  border-radius: 50%;
  animation: spin .6s linear infinite;
}
@keyframes spin { to{transform:rotate(360deg)} }

/* ==========================================================
   SETTINGS BLOCK (collapsible)
   ========================================================== */
.settings-block {
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  margin-bottom: 16px;
  overflow: hidden;
  background: var(--gray-50);
}

.settings-header {
  display: flex; align-items: center; gap: 8px;
  padding: 12px 16px;
  font-size: 0.82rem; font-weight: 600;
  color: var(--gray-700);
  border-bottom: 1px solid var(--gray-200);
}
.settings-header svg { color: var(--gray-400); flex-shrink: 0; }

.settings-block-open > :not(.settings-header) {
  padding: 0 16px 16px;
}
.settings-block-open > :nth-child(2) {
  padding-top: 16px;
}

.settings-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

.pipeline-section {
  /* no extra padding needed */
}

/* ==========================================================
   PARAM CARDS
   ========================================================== */
.param-card {
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-md);
  padding: 14px;
  transition: border-color .15s;
}
.param-card:hover { border-color: var(--gray-300); }

.param-card-header {
  font-size: 0.82rem; font-weight: 600;
  color: var(--gray-800);
  margin-bottom: 2px;
}
.param-card-desc {
  font-size: 0.7rem; color: var(--gray-500);
  margin-bottom: 10px; line-height: 1.4;
}
.param-card .input { font-size: 0.82rem; padding: 7px 10px; }

/* Toggle group */
.toggle-group { display: flex; gap: 4px; flex-wrap: wrap; }
.toggle-option {
  display: flex; align-items: center; gap: 6px;
  cursor: pointer; font-size: 0.78rem;
  padding: 5px 10px; border-radius: var(--radius-sm);
  transition: background .1s;
}
.toggle-option:hover { background: var(--gray-100); }
.toggle-option span { font-weight: 500; color: var(--gray-700); }
.toggle-option input[type="radio"] { accent-color: var(--sky-500); width: 14px; height: 14px; }

/* Switch */
.switch { display: flex; align-items: center; gap: 10px; cursor: pointer; }
.switch input { display: none; }
.switch-slider {
  width: 36px; height: 20px;
  background: var(--gray-300); border-radius: 10px;
  position: relative; transition: background .2s;
}
.switch-slider::after {
  content:''; width:16px; height:16px;
  background: var(--white); border-radius:50%;
  position: absolute; top:2px; left:2px;
  transition: transform .2s;
  box-shadow: 0 1px 2px rgba(0,0,0,.15);
}
.switch input:checked + .switch-slider { background: var(--sky-500); }
.switch input:checked + .switch-slider::after { transform: translateX(16px); }
.switch-label { font-size: 0.78rem; color: var(--gray-500); font-weight: 500; }

/* ==========================================================
   PIPELINE
   ========================================================== */
.preset-bar { display: flex; align-items: center; gap: 6px; flex-wrap: wrap; margin-bottom: 12px; }
.preset-label { font-size: 0.73rem; color: var(--gray-500); font-weight: 600; }

.preset-chip {
  padding: 5px 12px;
  border-radius: 999px;
  border: 1px solid var(--gray-300);
  background: var(--white);
  font-family: var(--font-sans);
  font-size: 0.73rem; font-weight: 500;
  color: var(--gray-600);
  cursor: pointer; transition: all .12s;
}
.preset-chip:hover { border-color: var(--sky-400); color: var(--sky-700); background: var(--sky-50); }
.preset-chip.active {
  background: var(--sky-500); border-color: var(--sky-500);
  color: var(--white); font-weight: 600;
}

.pipeline-track {
  display: flex; align-items: center; flex-wrap: wrap;
  padding: 14px;
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-md);
  min-height: 80px;
  margin-bottom: 12px;
  direction: ltr;
  gap: 4px 0;
}
.pipeline-track:empty::after {
  content:'Click a step below to add...';
  color: var(--gray-400); font-size: 0.82rem;
  width:100%; text-align:center; direction:ltr;
}

.pipe-step {
  display: flex; flex-direction: column; align-items: center; gap: 4px; flex-shrink: 0;
  cursor: grab; user-select: none; position: relative;
  transition: opacity .15s, transform .15s;
}
.pipe-step:active { cursor: grabbing; }
.pipe-step.dragging { opacity: 0.3; transform: scale(0.95); }

/* Drop indicator lines */
.pipe-step.drag-over-left::before,
.pipe-step.drag-over-right::after {
  content: '';
  position: absolute;
  top: 0; bottom: 0;
  width: 3px;
  background: var(--sky-500);
  border-radius: 2px;
  z-index: 10;
}
.pipe-step.drag-over-left::before { left: -8px; }
.pipe-step.drag-over-right::after { right: -8px; }

/* Touch drag floating clone */
.touch-drag-clone {
  position: fixed;
  z-index: 9999;
  pointer-events: none;
  opacity: 0.85;
  transform: scale(1.08);
  filter: drop-shadow(0 4px 12px rgba(0,0,0,.25));
}

.pipe-step-chip {
  display: flex; align-items: center; gap: 5px;
  padding: 7px 14px; color: var(--white);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.82rem; font-weight: 600;
  cursor: grab; border: 2px solid transparent;
  transition: all .12s; box-shadow: var(--shadow-sm);
}
.pipe-step-chip:hover { transform: translateY(-1px); box-shadow: var(--shadow-md); }

.pipe-step-chip .remove-step {
  width:16px;height:16px;border-radius:50%;
  background:rgba(255,255,255,.2);border:none;
  color:rgba(255,255,255,.8);font-size:.65rem;
  cursor:pointer;display:flex;align-items:center;justify-content:center;
  transition:all .1s;
}
.pipe-step-chip .remove-step:hover { background: var(--red-500); color:#fff; }

.pipe-step-params { font-size:.65rem; color:var(--gray-500); font-family:var(--font-mono); max-width:110px; text-align:center; overflow:hidden; text-overflow:ellipsis; white-space:nowrap; }

.pipe-arrow { font-size:1rem; color:var(--gray-400); padding:0 8px; flex-shrink:0; user-select:none; }

/* Step colors */
.pipe-step-chip[data-type="EO"]    { background: var(--blue-500); }
.pipe-step-chip[data-type="RZP"]   { background: var(--violet-500); }
.pipe-step-chip[data-type="DR"]    { background: var(--red-500); }
.pipe-step-chip[data-type="HTR"]   { background: var(--orange-500); }
.pipe-step-chip[data-type="FR"]    { background: var(--amber-500); }
.pipe-step-chip[data-type="FIN"]   { background: var(--green-500); }
.pipe-step-chip[data-type="FRLS"]  { background: #d97706; }
.pipe-step-chip[data-type="FINLS"] { background: var(--teal-500); }
.pipe-step-chip[data-type="VR"]    { background: var(--purple-500); }

.add-step-bar { display:flex; align-items:center; gap:6px; flex-wrap:wrap; margin-bottom:12px; font-size:.73rem; color:var(--gray-500); font-weight:600; }
.add-step-btn {
  padding:5px 12px; border-radius:var(--radius-sm);
  border:1px dashed var(--gray-300); background:transparent;
  font-family:var(--font-mono); font-size:.78rem; font-weight:600;
  color:var(--gray-600); cursor:pointer; transition:all .12s;
}
.add-step-btn:hover { border-color:var(--sky-500); border-style:solid; color:var(--sky-600); background:var(--sky-50); }


/* ==========================================================
   RESULTS
   ========================================================== */
.result-box {
  margin-top:16px;
  border:1px solid var(--gray-200);
  border-radius:var(--radius-lg);
  overflow:hidden;
  animation:fadeUp .25s ease;
}

.result-head {
  display:flex; justify-content:space-between; align-items:center;
  padding:10px 16px;
  background:var(--gray-50);
  border-bottom:1px solid var(--gray-100);
}
.result-head h3 { font-size:.78rem; font-weight:700; color:var(--gray-600); text-transform:uppercase; letter-spacing:.03em; }
.result-actions { display:flex; gap:4px; }

.result-box pre {
  padding:14px 16px;
  white-space:pre-wrap; word-break:break-word;
  font-family:var(--font-mono); font-size:.82rem; line-height:1.75;
  color:var(--gray-800); max-height:420px; overflow-y:auto;
  background:var(--white);
}




/* ==========================================================
   MODAL
   ========================================================== */
.modal-overlay {
  position:fixed; inset:0;
  background:rgba(15,23,42,.5);
  backdrop-filter:blur(4px);
  z-index:2000;
  display:flex; align-items:center; justify-content:center;
  animation:fadeIn .15s ease;
}
@keyframes fadeIn { from{opacity:0} to{opacity:1} }

.modal {
  background:var(--white);
  border:1px solid var(--gray-200);
  border-radius:var(--radius-xl);
  width:460px; max-width:95vw; max-height:85vh;
  overflow-y:auto;
  box-shadow:var(--shadow-xl);
  animation:modalUp .2s ease;
}
@keyframes modalUp { from{opacity:0;transform:translateY(12px)}to{opacity:1;transform:none} }

.modal-header {
  display:flex; justify-content:space-between; align-items:center;
  padding:16px 20px;
  border-bottom:1px solid var(--gray-100);
}
.modal-header h3 { font-size:.93rem; font-weight:700; }

.modal-close {
  background:none; border:none; color:var(--gray-400);
  font-size:1.3rem; cursor:pointer; line-height:1;
  width:30px; height:30px; border-radius:50%;
  display:flex; align-items:center; justify-content:center;
  transition:all .1s;
}
.modal-close:hover { background:var(--gray-100); color:var(--gray-700); }

.modal-body { padding:20px; }

.modal-footer {
  display:flex; gap:8px; justify-content:flex-start;
  padding:14px 20px;
  border-top:1px solid var(--gray-100);
}

.modal-field { margin-bottom:16px; }
.modal-field label { display:block; font-size:.82rem; color:var(--gray-700); margin-bottom:4px; font-weight:600; }
.modal-field-desc { font-size:.7rem; color:var(--gray-500); margin-bottom:6px; line-height:1.4; }
.modal-field input[type="number"],
.modal-field input[type="text"],
.modal-field select {
  width:100%; padding:8px 10px;
  background:var(--white); border:1px solid var(--gray-300);
  border-radius:var(--radius-sm); color:var(--gray-900);
  font-size:.85rem; font-family:var(--font-mono);
  transition:border-color .15s,box-shadow .15s;
}
.modal-field input:focus, .modal-field select:focus {
  outline:none; border-color:var(--sky-500);
  box-shadow:0 0 0 3px rgba(14,165,233,.12);
}
.modal-field .checkbox-row { display:flex; align-items:center; gap:8px; font-size:.85rem; }

.modal-step-title {
  font-size:.82rem; color:var(--gray-600);
  margin-bottom:14px; padding:10px 12px;
  background:var(--gray-50); border-radius:var(--radius-sm);
  line-height:1.6; border-left:3px solid var(--sky-500);
}

/* ==========================================================
   SUBSET CHIPS (for DR step modal)
   ========================================================== */
.subset-chips-container {
  display: flex; flex-wrap: wrap; gap: 6px;
}
.subset-chip {
  padding: 5px 12px;
  border-radius: 999px;
  border: 1px solid var(--gray-300);
  background: var(--white);
  font-family: var(--font-mono);
  font-size: 0.78rem; font-weight: 500;
  color: var(--gray-600);
  cursor: pointer; transition: all .12s;
  user-select: none;
}
.subset-chip:hover { border-color: var(--sky-400); color: var(--sky-700); background: var(--sky-50); }
.subset-chip.active {
  background: var(--sky-500); border-color: var(--sky-500);
  color: var(--white); font-weight: 600;
}
.trigger-custom-input {
  width: 100%; padding: 8px 10px;
  background: var(--white); border: 1px solid var(--gray-300);
  border-radius: var(--radius-sm); color: var(--gray-900);
  font-size: .85rem; font-family: var(--font-mono);
  transition: border-color .15s, box-shadow .15s;
}
.trigger-custom-input:focus {
  outline: none; border-color: var(--sky-500);
  box-shadow: 0 0 0 3px rgba(14,165,233,.12);
}

/* ==========================================================
   FOOTER
   ========================================================== */
footer {
  text-align:center; padding:24px 0; margin-top:32px;
  border-top:1px solid var(--gray-200);
  color:var(--gray-500); font-size:.78rem;
}
footer a { color:var(--sky-600); text-decoration:none; font-weight:500; transition:color .1s; }
footer a:hover { color:var(--sky-700); text-decoration:underline; }

/* ==========================================================
   RESPONSIVE
   ========================================================== */
@media(max-width:768px){
  .topbar-inner { height:auto; padding:12px 16px; }
  .brand-name { font-size: 2.2rem; }
  .shell { padding:12px 12px 32px; }
  .settings-grid { grid-template-columns:1fr 1fr; }
  .card-body { padding: 14px; }
  .btn-lg { padding: 12px 16px; font-size: 0.87rem; }
  .pipeline-track { padding: 10px; min-height: 60px; }
  .pipe-step-chip { padding: 6px 10px; font-size: 0.75rem; }
  .pipe-arrow { padding: 0 4px; font-size: 0.85rem; }
  .modal { max-width: 98vw; max-height: 90vh; margin: 8px; }
  .modal-body { padding: 14px; }
  .modal-header { padding: 12px 14px; }
  .modal-footer { padding: 10px 14px; }
  .result-box pre { font-size: .75rem; padding: 10px 12px; max-height: 300px; }
  .preset-bar { gap: 4px; }
  .add-step-bar { gap: 4px; }
  .add-step-btn { padding: 4px 8px; font-size: .72rem; }
  .settings-header { padding: 10px 12px; font-size: 0.78rem; }
  .settings-block-open > :not(.settings-header) { padding: 0 12px 12px; }
  .settings-block-open > :nth-child(2) { padding-top: 12px; }
}
@media(max-width:480px){
  .settings-grid { grid-template-columns:1fr; }
  .brand-name { font-size: 1.8rem; }
  .topbar-inner { padding: 10px 12px; }
  .shell { padding: 8px 8px 24px; }
  .card-body { padding: 10px; }
  .field-row { flex-direction: column; }
  .field-row .input { width: 100%; }
  .solve-buttons { flex-direction: column; }
  .solve-buttons .btn-lg { width: 100%; }
  .subset-chips-container { gap: 4px; }
  .subset-chip { padding: 4px 9px; font-size: 0.72rem; }
  .toggle-group { flex-direction: column; gap: 2px; }
  .param-card { padding: 10px; }
  .pipe-step-params { max-width: 80px; font-size: .6rem; }
}