:root{
  --paper:#F1F0E8;
  --paper-raised:#FAFAF5;
  --ink:#1B2420;
  --ink-soft:#4A5650;
  --line:#DAD5C6;
  --red:#C1453B;
  --violet:#5B4FCF;
  --teal:#2C6E5F;
  --gold:#C6963A;
  --grey:#9A968A;
  --mono:'Space Mono', monospace;
  --sans:'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
}

*{ box-sizing:border-box; }
html{ scroll-behavior:smooth; }
body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:var(--sans);
  line-height:1.5;
  -webkit-font-smoothing:antialiased;
}
.wrap{ max-width:760px; margin:0 auto; padding:0 24px; }

/* signature element: indicator rail — a thin strip whose color reflects the
   most recent reaction's classification (acid-driven / base-driven /
   displacement / neutral / none yet) */
.indicator-rail{
  height:5px;
  width:100%;
  background:linear-gradient(90deg, var(--grey), var(--grey));
  transition:background 0.5s ease;
}
@media (prefers-reduced-motion:reduce){ .indicator-rail{ transition:none; } }

/* ---------------------------------------------------------------------- */
/* Top nav bar — logo + hamburger, sits above the hero                     */
/* ---------------------------------------------------------------------- */
.top-nav{
  position:sticky;
  top:0;
  z-index:60;
  background:var(--ink);
  border-bottom:1px solid rgba(198,150,58,0.25);
}
.top-nav-inner{
  max-width:760px;
  margin:0 auto;
  padding:13px 24px;
  display:flex;
  align-items:center;
  justify-content:space-between;
}
.brand{
  display:flex;
  align-items:center;
  gap:10px;
  text-decoration:none;
  color:var(--paper);
}
.brand-mark{ flex-shrink:0; }
.brand-name{
  font-family:var(--mono);
  font-weight:700;
  font-size:16px;
  letter-spacing:0.02em;
}

.hamburger{
  width:32px;
  height:24px;
  padding:2px;
  display:flex;
  flex-direction:column;
  justify-content:space-between;
  background:none;
  border:none;
  cursor:pointer;
}
.hamburger span{
  display:block;
  height:2px;
  background:var(--paper);
  border-radius:2px;
  transition:transform 0.3s ease, opacity 0.3s ease;
}
.hamburger.open span:nth-child(1){ transform:translateY(10px) rotate(45deg); }
.hamburger.open span:nth-child(2){ opacity:0; }
.hamburger.open span:nth-child(3){ transform:translateY(-10px) rotate(-45deg); }
@media (prefers-reduced-motion:reduce){ .hamburger span{ transition:none; } }

/* ---------------------------------------------------------------------- */
/* Drawer                                                                   */
/* ---------------------------------------------------------------------- */
.drawer-overlay{
  position:fixed; inset:0;
  background:rgba(27,36,32,0.5);
  z-index:70;
  opacity:0;
  transition:opacity 0.3s ease;
}
.drawer-overlay[hidden]{ display:none !important; }
.drawer-overlay.show{ opacity:1; }

.drawer{
  position:fixed;
  top:0; right:0;
  height:100vh;
  width:min(340px, 88vw);
  background:var(--paper-raised);
  z-index:80;
  transform:translateX(100%);
  transition:transform 0.4s cubic-bezier(0.22,0.68,0.2,1);
  box-shadow:-18px 0 40px -14px rgba(0,0,0,0.35);
  display:flex;
  flex-direction:column;
  overflow-y:auto;
}
.drawer.open{ transform:translateX(0); }
@media (prefers-reduced-motion:reduce){
  .drawer{ transition:none; }
  .drawer-overlay{ transition:none; }
}

.drawer-head{
  display:flex;
  align-items:center;
  justify-content:space-between;
  padding:18px 20px;
  border-bottom:1px solid var(--line);
}
.drawer-title{
  font-family:var(--mono);
  font-size:11px;
  letter-spacing:0.18em;
  text-transform:uppercase;
  color:var(--ink-soft);
}
.drawer-close{
  background:none;
  border:none;
  cursor:pointer;
  font-size:15px;
  color:var(--ink-soft);
  width:30px; height:30px;
  border-radius:6px;
}
.drawer-close:hover{ background:var(--paper); color:var(--ink); }

.drawer-body{ padding:8px 10px 30px; }

.drawer-link{
  display:block;
  font-family:var(--sans);
  font-weight:600;
  font-size:15.5px;
  color:var(--ink);
  text-decoration:none;
  padding:13px 12px;
  border-radius:6px;
}
.drawer-link:hover{ background:var(--paper); }
.drawer-link.active{ color:var(--teal); }

.drawer-section-toggle{
  width:100%;
  display:flex;
  align-items:center;
  justify-content:space-between;
  background:none;
  border:none;
  cursor:pointer;
  font-family:var(--sans);
  font-weight:600;
  font-size:15.5px;
  color:var(--ink);
  padding:13px 12px;
  text-align:left;
  border-radius:6px;
}
.drawer-section-toggle:hover{ background:var(--paper); }
.drawer-section-toggle .chev{
  font-family:var(--mono);
  color:var(--gold);
  transition:transform 0.3s ease;
  margin-left:10px;
}
.drawer-section.open .drawer-section-toggle .chev{ transform:rotate(180deg); }

.drawer-submenu-wrap{
  display:grid;
  grid-template-rows:0fr;
  transition:grid-template-rows 0.32s ease;
}
.drawer-section.open .drawer-submenu-wrap{ grid-template-rows:1fr; }
.drawer-submenu{ overflow:hidden; min-height:0; }
.drawer-submenu a, .drawer-submenu button{
  display:block;
  width:100%;
  font-family:var(--mono);
  font-size:12.5px;
  color:var(--ink-soft);
  text-decoration:none;
  padding:10px 12px 10px 24px;
  border-left:1px dashed var(--line);
  margin-left:12px;
  background:none;
  border-top:none; border-right:none; border-bottom:none;
  cursor:pointer;
  text-align:left;
}
.drawer-submenu a:hover, .drawer-submenu button:hover{ color:var(--teal); }
.drawer-submenu a.active{ color:var(--teal); }
@media (prefers-reduced-motion:reduce){ .drawer-submenu-wrap{ transition:none; } }

.site-header{ padding:56px 0 32px; border-bottom:1px solid var(--line); }
.eyebrow{
  font-family:var(--mono);
  font-size:12px;
  letter-spacing:0.14em;
  text-transform:uppercase;
  color:var(--teal);
  display:inline-block;
  margin-bottom:18px;
}
h1{
  font-family:var(--sans);
  font-weight:700;
  font-size:clamp(32px, 5vw, 48px);
  line-height:1.08;
  letter-spacing:-0.02em;
  margin:0 0 16px;
}
.lede{
  font-size:16px;
  color:var(--ink-soft);
  max-width:52ch;
  margin:0;
}

main{ padding-bottom:64px; }

.equation-card{ padding:40px 0 12px; }
.equation-bar{
  display:flex;
  align-items:flex-end;
  gap:14px;
  flex-wrap:wrap;
  background:var(--paper-raised);
  border:1px solid var(--line);
  border-radius:10px;
  padding:20px;
}
.field{ display:flex; flex-direction:column; gap:6px; flex:1 1 160px; min-width:140px; }
.field label{
  font-family:var(--mono);
  font-size:11px;
  letter-spacing:0.08em;
  text-transform:uppercase;
  color:var(--ink-soft);
}
.field input{
  font-family:var(--mono);
  font-size:20px;
  padding:10px 12px;
  border:1px solid var(--line);
  border-radius:6px;
  background:#fff;
  color:var(--ink);
  width:100%;
}
.field input:focus{
  outline:2px solid var(--teal);
  outline-offset:1px;
  border-color:var(--teal);
}
.operator{
  font-family:var(--mono);
  font-size:24px;
  color:var(--ink-soft);
  padding-bottom:10px;
}
.predict-btn{
  font-family:var(--sans);
  font-weight:600;
  font-size:15px;
  background:var(--teal);
  color:#fff;
  border:none;
  border-radius:6px;
  padding:12px 20px;
  cursor:pointer;
  display:flex;
  align-items:center;
  gap:8px;
  transition:background 0.15s ease, transform 0.15s ease;
}
.predict-btn:hover{ background:#245a4d; }
.predict-btn:focus-visible{ outline:2px solid var(--ink); outline-offset:2px; }
.predict-btn .arrow{ transition:transform 0.15s ease; }
.predict-btn:hover .arrow{ transform:translateX(3px); }
@media (prefers-reduced-motion:reduce){ .predict-btn, .predict-btn .arrow{ transition:none; } }

.hint{ font-size:13px; color:var(--ink-soft); margin:14px 4px 0; }
.hint-fill{
  font-family:var(--mono);
  font-size:13px;
  background:none;
  border:none;
  border-bottom:1px dotted var(--ink-soft);
  color:var(--ink);
  cursor:pointer;
  padding:0;
}
.hint-fill:hover{ color:var(--teal); border-color:var(--teal); }

.result-card{
  margin-top:24px;
  border:1px solid var(--line);
  border-radius:10px;
  overflow:hidden;
  background:var(--paper-raised);
}
.result-strip{ height:6px; background:var(--grey); }
.result-body{ padding:28px 24px; }
.result-equation{
  font-family:var(--mono);
  font-size:clamp(20px, 4vw, 28px);
  line-height:1.4;
  word-break:break-word;
}
.result-equation .coef{ color:var(--ink-soft); }
.result-equation .arrow-sep{ color:var(--gold); margin:0 10px; }
.result-meta{ margin-top:16px; padding-top:16px; border-top:1px dashed var(--line); }
.result-label{
  font-family:var(--mono);
  font-size:12px;
  letter-spacing:0.06em;
  text-transform:uppercase;
  color:var(--teal);
  font-weight:700;
}
.result-note{ margin:8px 0 0; color:var(--ink-soft); font-size:14.5px; }

.section-title{
  font-family:var(--mono);
  font-size:13px;
  letter-spacing:0.08em;
  text-transform:uppercase;
  color:var(--ink-soft);
  margin:0 0 14px;
}
.picker-section{ margin-top:48px; }
.picker-groups{ display:flex; flex-direction:column; gap:14px; }
.picker-group{ display:flex; align-items:baseline; gap:10px; flex-wrap:wrap; }
.picker-group-label{ font-size:13px; color:var(--ink-soft); min-width:76px; font-weight:600; }
.chip{
  font-family:var(--mono);
  font-size:13px;
  background:#fff;
  border:1px solid var(--line);
  border-radius:20px;
  padding:6px 12px;
  cursor:pointer;
  color:var(--ink);
}
.chip:hover{ border-color:var(--teal); color:var(--teal); }

.browser-section{ margin-top:40px; }
#elementDetails summary{
  cursor:pointer;
  font-family:var(--mono);
  font-size:13px;
  letter-spacing:0.06em;
  text-transform:uppercase;
  color:var(--ink-soft);
  padding:10px 0;
  border-top:1px solid var(--line);
  border-bottom:1px solid var(--line);
}
.element-grid{
  display:grid;
  grid-template-columns:repeat(auto-fill, minmax(52px, 1fr));
  gap:6px;
  margin-top:16px;
  max-height:340px;
  overflow-y:auto;
  padding-right:4px;
}
.el-btn{
  font-family:var(--mono);
  font-size:13px;
  font-weight:700;
  aspect-ratio:1;
  border:1px solid var(--line);
  border-radius:6px;
  background:#fff;
  cursor:pointer;
  color:var(--ink);
  display:flex;
  align-items:center;
  justify-content:center;
}
.el-btn:hover{ border-color:var(--ink); }
.el-btn[data-cat="alkali"]{ background:#FBEAE8; }
.el-btn[data-cat="alkaline"]{ background:#FCEFE0; }
.el-btn[data-cat="transition"]{ background:#E8F0EE; }
.el-btn[data-cat="posttransition"]{ background:#EFF1E4; }
.el-btn[data-cat="lanthanide"]{ background:#EFEAF6; }
.el-btn[data-cat="actinide"]{ background:#F6EAF0; }
.el-btn[data-cat="metalloid"]{ background:#F4F0E2; }
.el-btn[data-cat="nonmetal"]{ background:#E7EEF2; }
.el-btn[data-cat="halogen"]{ background:#FDF1E6; }
.el-btn[data-cat="noble"]{ background:#F0F0F0; color:var(--grey); }

.periodic-section{ margin-top:40px; }
.periodic-hint{ font-size:13.5px; color:var(--ink-soft); margin:0 0 16px; }
.periodic-scroll{
  overflow-x:auto;
  padding-bottom:8px;
  -webkit-overflow-scrolling:touch;
}
.periodic-grid{
  display:grid;
  grid-template-columns:repeat(18, minmax(38px, 1fr));
  grid-auto-rows:minmax(38px, auto);
  gap:3px;
  min-width:720px;
}
.pt-cell{
  font-family:var(--mono);
  border:1px solid var(--line);
  border-radius:4px;
  background:#fff;
  cursor:pointer;
  display:flex;
  flex-direction:column;
  align-items:center;
  justify-content:center;
  padding:2px;
  line-height:1.1;
  color:var(--ink);
  min-width:0;
}
.pt-cell:hover{ outline:2px solid var(--ink); outline-offset:-2px; }
.pt-cell .pt-num{ font-size:7px; color:var(--ink-soft); align-self:flex-start; margin-left:2px; }
.pt-cell .pt-sym{ font-size:13px; font-weight:700; }
.pt-cell.pt-spacer{ background:transparent; border:none; cursor:default; }
.pt-cell.pt-spacer:hover{ outline:none; }
.pt-cell[data-cat="alkali"]{ background:#FBEAE8; }
.pt-cell[data-cat="alkaline"]{ background:#FCEFE0; }
.pt-cell[data-cat="transition"]{ background:#E8F0EE; }
.pt-cell[data-cat="posttransition"]{ background:#EFF1E4; }
.pt-cell[data-cat="lanthanide"]{ background:#EFEAF6; }
.pt-cell[data-cat="actinide"]{ background:#F6EAF0; }
.pt-cell[data-cat="metalloid"]{ background:#F4F0E2; }
.pt-cell[data-cat="nonmetal"]{ background:#E7EEF2; }
.pt-cell[data-cat="halogen"]{ background:#FDF1E6; }
.pt-cell[data-cat="noble"]{ background:#F0F0F0; color:var(--grey); }

.modal-overlay{
  position:fixed; inset:0;
  background:rgba(27,36,32,0.45);
  display:flex; align-items:center; justify-content:center;
  padding:20px;
  z-index:100;
}
.modal-overlay[hidden]{
  display:none !important;
}
.modal{
  background:#fff;
  border-radius:12px;
  max-width:480px;
  width:100%;
  max-height:86vh;
  overflow-y:auto;
  padding:28px;
  position:relative;
}
.modal-close{
  position:absolute; top:14px; right:14px;
  background:none; border:none;
  font-size:16px; cursor:pointer;
  color:var(--ink-soft);
  width:32px; height:32px;
  border-radius:6px;
}
.modal-close:hover{ background:var(--paper); }
.modal-head{ display:flex; align-items:center; gap:16px; margin-bottom:20px; }
.modal-symbol{
  font-family:var(--mono);
  font-size:36px;
  font-weight:700;
  background:var(--paper);
  border:1px solid var(--line);
  border-radius:10px;
  width:64px; height:64px;
  display:flex; align-items:center; justify-content:center;
  flex-shrink:0;
}
.modal-name{ font-size:20px; font-weight:700; }
.modal-cat{ font-size:13px; color:var(--teal); font-family:var(--mono); text-transform:uppercase; letter-spacing:0.04em; }
.modal-grid{
  display:grid;
  grid-template-columns:1fr 1fr;
  gap:12px 16px;
}
.modal-item{ border-top:1px dashed var(--line); padding-top:8px; }
.modal-item-label{ font-size:11px; text-transform:uppercase; letter-spacing:0.06em; color:var(--ink-soft); font-family:var(--mono); }
.modal-item-value{ font-size:14.5px; margin-top:3px; font-family:var(--mono); word-break:break-word; }
@media (max-width:480px){
  .modal-grid{ grid-template-columns:1fr; }
  .modal{ padding:22px; }
}

.scope-note{
  margin-top:48px;
  padding-top:24px;
  border-top:1px solid var(--line);
  font-size:14.5px;
  color:var(--ink-soft);
}
.scope-note ul{ padding-left:20px; margin:0 0 14px; }
.scope-note li{ margin-bottom:6px; }

.info-card{
  margin-top:8px;
  border:1px solid var(--line);
  border-radius:10px;
  overflow:hidden;
  background:var(--paper-raised);
}
.info-strip{ height:6px; background:var(--teal); }
.info-body{ padding:32px 28px; }
.info-kicker{
  font-family:var(--mono);
  font-size:12px;
  letter-spacing:0.06em;
  text-transform:uppercase;
  color:var(--teal);
  font-weight:700;
  display:block;
  margin-bottom:10px;
}
.info-body h2{
  font-family:var(--sans);
  font-weight:700;
  font-size:24px;
  margin:0 0 14px;
}
.info-body p{ color:var(--ink-soft); line-height:1.65; margin:0 0 12px; }
.info-placeholder{
  margin-top:18px;
  padding-top:16px;
  border-top:1px dashed var(--line);
  font-family:var(--mono);
  font-size:12.5px;
  color:var(--ink-soft);
}

.back-link{
  display:inline-block;
  margin-top:28px;
  font-family:var(--mono);
  font-size:12.5px;
  letter-spacing:0.03em;
  color:var(--ink-soft);
  text-decoration:none;
}
.back-link:hover{ color:var(--teal); }

/* Contact page form, styled like the equation-bar inputs */
.contact-form{
  display:flex;
  flex-direction:column;
  gap:20px;
}
.contact-field label{
  display:block;
  font-family:var(--mono);
  font-size:11px;
  letter-spacing:0.08em;
  text-transform:uppercase;
  color:var(--ink-soft);
  margin-bottom:6px;
}
.contact-field .req{ color:var(--red); margin-left:3px; }
.contact-field input, .contact-field textarea{
  width:100%;
  font-family:var(--sans);
  font-size:15.5px;
  padding:11px 12px;
  border:1px solid var(--line);
  border-radius:6px;
  background:#fff;
  color:var(--ink);
}
.contact-field input:focus, .contact-field textarea:focus{
  outline:2px solid var(--teal);
  outline-offset:1px;
  border-color:var(--teal);
}
.contact-field textarea{ resize:vertical; min-height:110px; }
.contact-two-col{ display:grid; grid-template-columns:1fr 1fr; gap:20px; }
@media (max-width:480px){ .contact-two-col{ grid-template-columns:1fr; } }
.contact-submit-row{
  display:flex;
  align-items:center;
  justify-content:space-between;
  margin-top:4px;
  padding-top:20px;
  border-top:1px dashed var(--line);
  flex-wrap:wrap;
  gap:12px;
}
.contact-sig{ font-family:var(--mono); font-size:13px; color:var(--ink-soft); font-style:italic; }
.contact-status{
  margin-top:4px;
  font-family:var(--mono);
  font-size:12.5px;
  min-height:18px;
}
.contact-status.ok{ color:var(--teal); }
.contact-status.err{ color:var(--red); }
.hp{ position:absolute; left:-9999px; opacity:0; height:0; }

/* ---------------------------------------------------------------------- */
/* Tic-Tac-Toe game (opened from the drawer, reuses .modal/.modal-overlay) */
/* ---------------------------------------------------------------------- */
button.drawer-link{
  background:none;
  border:none;
  cursor:pointer;
  width:100%;
  text-align:left;
  font-family:inherit;
}

.game-modal{ max-width:400px; }
.game-head{ text-align:center; margin-bottom:16px; }
.game-title{
  font-family:var(--sans);
  font-weight:700;
  font-size:22px;
  margin:2px 0 0;
}

.game-modes{
  display:flex;
  gap:8px;
  justify-content:center;
  margin-bottom:18px;
}
.game-mode-btn{
  font-family:var(--mono);
  font-size:12.5px;
  padding:8px 16px;
  border-radius:20px;
  border:1px solid var(--line);
  background:#fff;
  cursor:pointer;
  color:var(--ink-soft);
}
.game-mode-btn.active{
  background:var(--ink);
  color:var(--paper);
  border-color:var(--ink);
}

.game-status{
  text-align:center;
  font-family:var(--sans);
  font-size:14.5px;
  color:var(--ink-soft);
  margin-bottom:16px;
  min-height:20px;
}
.mark-label{ font-family:var(--mono); font-weight:700; }
.mark-label-x{ color:var(--teal); }
.mark-label-o{ color:var(--red); }

.game-board-wrap{
  position:relative;
  width:100%;
  max-width:264px;
  margin:0 auto;
}
.game-board{
  display:grid;
  grid-template-columns:repeat(3,1fr);
  grid-template-rows:repeat(3,1fr);
  gap:7px;
  aspect-ratio:1;
}
.game-cell{
  border:1px solid var(--line);
  border-radius:10px;
  background:#fff;
  cursor:pointer;
  display:flex;
  align-items:center;
  justify-content:center;
  padding:6px;
}
.game-cell:hover:not(.filled):not(.disabled){
  border-color:var(--teal);
  background:var(--paper);
}
.game-cell.disabled{ cursor:default; }
.game-cell.win-cell{ background:rgba(198,150,58,0.14); border-color:var(--gold); }
.game-cell svg{ width:100%; height:100%; overflow:visible; }
.game-cell.mark-x svg .mark-path{ stroke:var(--teal); }
.game-cell.mark-o svg .mark-path{ stroke:var(--red); }
.game-cell svg .mark-path{
  fill:none;
  stroke-width:5.5;
  stroke-linecap:round;
  stroke-dasharray:110;
  stroke-dashoffset:110;
  transition:stroke-dashoffset 0.35s ease;
}
.game-cell svg .mark-path.drawn{ stroke-dashoffset:0; }
@media (prefers-reduced-motion:reduce){
  .game-cell svg .mark-path{ transition:none; }
}

.win-line-svg{
  position:absolute;
  inset:0;
  width:100%;
  height:100%;
  pointer-events:none;
}
.win-line{
  stroke:var(--gold);
  stroke-width:5;
  stroke-linecap:round;
  transition:stroke-dashoffset 0.4s ease;
}
@media (prefers-reduced-motion:reduce){ .win-line{ transition:none; } }

.game-footer{
  margin-top:22px;
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:12px;
  flex-wrap:wrap;
}
.game-score{
  display:flex;
  gap:14px;
  font-family:var(--mono);
  font-size:12.5px;
  color:var(--ink-soft);
}
.game-reset-btn{ padding:10px 18px; font-size:12.5px; }

@media (max-width:420px){
  .game-modal{ max-width:100%; }
}

.site-footer{
  border-top:1px solid var(--line);
  padding:24px 0 48px;
  font-family:var(--mono);
  font-size:12px;
  color:var(--ink-soft);
}

@media (max-width:520px){
  .equation-bar{ flex-direction:column; align-items:stretch; }
  .operator{ align-self:center; padding:0; }
  .predict-btn{ justify-content:center; }
}

/* ---------------------------------------------------------------------- */
/* Sudoku Game Styling                                                   */
/* ---------------------------------------------------------------------- */
.sudoku-container {
  max-width: 480px;
  margin: 20px auto;
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 16px;
  box-shadow: 0 8px 24px rgba(27,36,32,0.06);
  display: flex;
  flex-direction: column;
  gap: 16px;
  position: relative;
}

.sudoku-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--line);
  padding-bottom: 12px;
}

.sudoku-header-left {
  display: flex;
  align-items: center;
  gap: 12px;
}

.sudoku-back-btn {
  background: none;
  border: none;
  font-size: 20px;
  cursor: pointer;
  color: var(--ink);
  padding: 4px 8px;
  border-radius: 4px;
  display: flex;
  align-items: center;
  justify-content: center;
}
.sudoku-back-btn:hover {
  background: var(--paper);
}

.sudoku-title-block {
  display: flex;
  flex-direction: column;
}

.sudoku-title {
  font-family: var(--sans);
  font-weight: 700;
  font-size: 18px;
  margin: 0;
  color: var(--ink);
}

.sudoku-subtitle {
  font-size: 11px;
  color: var(--ink-soft);
  margin: 0;
}

.sudoku-header-right {
  display: flex;
  align-items: center;
  gap: 10px;
}

.sudoku-icon-btn {
  background: none;
  border: none;
  font-size: 18px;
  cursor: pointer;
  color: var(--ink-soft);
  width: 32px;
  height: 32px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
}
.sudoku-icon-btn:hover {
  background: var(--paper);
  color: var(--ink);
}

/* Info Bar */
.sudoku-info-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--mono);
  font-size: 13px;
  color: var(--ink-soft);
}

.sudoku-level-name {
  font-weight: 700;
  color: var(--ink);
}

.sudoku-reset-link {
  color: var(--ink-soft);
  text-decoration: none;
  cursor: pointer;
  border-bottom: 1px dotted var(--ink-soft);
}
.sudoku-reset-link:hover {
  color: var(--teal);
  border-color: var(--teal);
}

/* 6x6 Grid */
.sudoku-grid {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  grid-template-rows: repeat(6, 1fr);
  gap: 0;
  background: var(--ink);
  border: 3px solid var(--ink);
  border-radius: 12px;
  overflow: hidden;
  aspect-ratio: 1;
  width: 100%;
}

.sudoku-cell {
  background: #FFF;
  border: 1px solid var(--line);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  cursor: pointer;
  user-select: none;
  aspect-ratio: 1;
}

/* Thick borders for blocks */
/* Horizontal lines: after row 2 (index 1) and row 4 (index 3) */
.sudoku-cell[data-row="1"] {
  border-bottom: 2.5px solid var(--ink);
}
.sudoku-cell[data-row="3"] {
  border-bottom: 2.5px solid var(--ink);
}
/* Vertical lines: after col 3 (index 2) */
.sudoku-cell[data-col="2"] {
  border-right: 2.5px solid var(--ink);
}

/* Selected, highlighted, values */
.sudoku-cell.selected {
  outline: 3px solid var(--teal) !important;
  outline-offset: -3px;
  background-color: #E8F0EE !important;
  z-index: 10;
}

.sudoku-cell.highlighted-peer {
  background-color: #F8F7F0; /* Soft beige highlight for row/col/block peers */
}

.sudoku-cell.highlighted-value {
  background-color: #EBF2EF; /* Slightly greener tint for same numbers */
}

.sudoku-cell.completed-flash {
  animation: sudoku-flash 0.6s ease;
}

@keyframes sudoku-flash {
  0% { background-color: #FFF; }
  50% { background-color: #A3C9B8; }
  100% { background-color: #FFF; }
}

.sudoku-cell-val {
  font-family: var(--sans);
  font-size: 24px;
  font-weight: 500;
  text-align: center;
}

.sudoku-cell.clue .sudoku-cell-val {
  font-weight: 700;
  color: var(--ink);
}

.sudoku-cell.user-filled .sudoku-cell-val {
  color: var(--ink-soft);
}

.sudoku-cell.conflict .sudoku-cell-val {
  color: var(--red);
}

/* Notes / candidates */
.sudoku-notes-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(2, 1fr);
  width: 100%;
  height: 100%;
  padding: 3px;
  box-sizing: border-box;
}

.sudoku-note-cell {
  font-family: var(--mono);
  font-size: 9px;
  color: var(--grey);
  display: flex;
  align-items: center;
  justify-content: center;
  line-height: 1;
}

/* Control Row (Hint and Notes) */
.sudoku-controls {
  display: flex;
  justify-content: space-around;
  align-items: center;
  border-bottom: 1px solid var(--line);
  padding: 8px 0;
}

.sudoku-control-btn {
  background: none;
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--sans);
  font-weight: 600;
  font-size: 14px;
  color: var(--ink-soft);
  padding: 8px 16px;
  border-radius: 20px;
  transition: all 0.2s ease;
}
.sudoku-control-btn:hover {
  background: var(--paper);
  color: var(--ink);
}
.sudoku-control-btn.active {
  color: var(--teal);
  background: #E8F0EE;
}
.sudoku-control-btn.active svg {
  stroke: var(--teal);
  fill: var(--teal);
}

/* Keypad */
.sudoku-keypad {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  width: 100%;
}

.sudoku-key-btn {
  background: #FFF;
  border: 1px solid var(--line);
  border-radius: 12px;
  font-family: var(--sans);
  font-size: 20px;
  font-weight: 600;
  color: var(--ink);
  aspect-ratio: 1.4;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  transition: background 0.15s ease, border-color 0.15s ease;
}
.sudoku-key-btn:hover:not(:disabled) {
  background: var(--paper);
  border-color: var(--ink-soft);
}
.sudoku-key-btn:disabled {
  opacity: 0.25;
  cursor: not-allowed;
  background: var(--paper-raised);
}

.sudoku-key-btn .key-label {
  font-size: 11px;
  font-family: var(--sans);
  font-weight: 500;
  color: var(--ink-soft);
  margin-top: 2px;
}

/* Victory Overlay */
.sudoku-victory-overlay {
  position: absolute;
  inset: 0;
  background: var(--paper);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 100;
  padding: 16px;
  border-radius: 16px;
  overflow: hidden;
}

.sudoku-victory-card {
  background: #469567; /* Green card */
  color: #FFF;
  border-radius: 16px;
  width: 100%;
  padding: 24px 16px;
  text-align: center;
  position: relative;
  box-shadow: 0 10px 30px rgba(70,149,103,0.25);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  box-sizing: border-box;
}

.sudoku-victory-icon {
  font-size: 40px;
  margin-bottom: 4px;
  animation: float 2s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}

.sudoku-victory-level {
  font-family: var(--mono);
  font-size: 13px;
  opacity: 0.9;
  letter-spacing: 0.05em;
}

.sudoku-victory-title {
  font-family: var(--sans);
  font-weight: 700;
  font-size: 28px;
  margin: 0;
  line-height: 1.2;
}

/* Inner white stats card */
.sudoku-stats-card {
  background: #FFF;
  color: var(--ink);
  border-radius: 12px;
  width: 100%;
  padding: 16px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  margin-top: 10px;
  box-sizing: border-box;
}

.sudoku-mini-grid {
  width: 60px;
  height: 60px;
  border: 1.5px solid var(--ink);
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  grid-template-rows: repeat(6, 1fr);
  gap: 0px;
  background: var(--ink);
}

.sudoku-mini-cell {
  background: #A3C9B8; /* Solved cell style */
  aspect-ratio: 1;
}
.sudoku-mini-cell.mini-clue {
  background: #FFF;
}

.sudoku-stats-time {
  font-family: var(--mono);
  font-size: 28px;
  font-weight: 700;
}

.sudoku-stats-avg {
  font-family: var(--sans);
  font-size: 12px;
  color: var(--ink-soft);
}

/* Carousel dots */
.sudoku-carousel-dots {
  display: flex;
  gap: 6px;
  margin-top: 10px;
}

.sudoku-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: rgba(255,255,255,0.4);
}
.sudoku-dot.active {
  background: #FFF;
}

/* Action Circle Buttons */
.sudoku-victory-actions {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-top: 20px;
  width: 100%;
}

.sudoku-action-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
}

.sudoku-action-btn {
  background: #FFF;
  border: none;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--ink);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.sudoku-action-btn:hover {
  transform: scale(1.1);
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.sudoku-action-label {
  font-size: 11px;
  color: var(--ink-soft);
  font-family: var(--mono);
}

/* Top button pills in header */
.sudoku-pill-btn {
  background: #FFF;
  border: 1px solid var(--ink);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 12px;
  font-weight: 600;
  padding: 6px 14px;
  border-radius: 20px;
  cursor: pointer;
  text-decoration: none;
  display: inline-block;
  line-height: 1.2;
}
.sudoku-pill-btn:hover {
  background: var(--paper);
}

/* Confetti styling */
.confetti-container {
  position: absolute;
  inset: 0;
  pointer-events: none;
  overflow: hidden;
  z-index: 101;
}

.confetti {
  position: absolute;
  width: 8px;
  height: 8px;
  opacity: 0.8;
  pointer-events: none;
  animation: fall linear forwards;
}

@keyframes fall {
  0% { transform: translateY(-50px) rotate(0deg); opacity: 1; }
  100% { transform: translateY(400px) rotate(360deg); opacity: 0; }
}

/* Landing Page Game Menu styles */
.games-hub {
  display: flex;
  flex-direction: column;
  gap: 20px;
  margin-top: 32px;
}

.game-card {
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 24px;
  cursor: pointer;
  transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
  display: flex;
  justify-content: space-between;
  align-items: center;
  text-decoration: none;
  color: inherit;
}

.game-card:hover {
  transform: translateY(-2px);
  border-color: var(--teal);
  box-shadow: 0 6px 18px rgba(44,110,95,0.06);
}

.game-card-info {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.game-card-title {
  font-size: 18px;
  font-weight: 700;
  margin: 0;
  color: var(--ink);
}

.game-card-desc {
  font-size: 14px;
  color: var(--ink-soft);
  margin: 0;
}

.game-card-icon {
  font-size: 32px;
}

/* ---------------------------------------------------------------------- */
/* Completed Row, Column, Block celebration effects                       */
/* ---------------------------------------------------------------------- */
.sudoku-cell.row-completed,
.sudoku-cell.col-completed,
.sudoku-cell.block-completed {
  background-color: rgba(70, 149, 103, 0.15) !important;
}

/* Outlines for completed rows, columns, and blocks */
.sudoku-cell.border-top-comp {
  border-top: 2.5px solid #469567 !important;
}
.sudoku-cell.border-bottom-comp {
  border-bottom: 2.5px solid #469567 !important;
}
.sudoku-cell.border-left-comp {
  border-left: 2.5px solid #469567 !important;
}
.sudoku-cell.border-right-comp {
  border-right: 2.5px solid #469567 !important;
}

/* Green dot elements inside internal cell borders */
.sudoku-completed-dot-right {
  position: absolute;
  right: -4.5px;
  top: calc(50% - 4px);
  width: 8px;
  height: 8px;
  background-color: #469567;
  border-radius: 50%;
  box-shadow: 0 0 6px rgba(70,149,103,0.8);
  z-index: 20;
  pointer-events: none;
}

.sudoku-completed-dot-bottom {
  position: absolute;
  bottom: -4.5px;
  left: calc(50% - 4px);
  width: 8px;
  height: 8px;
  background-color: #469567;
  border-radius: 50%;
  box-shadow: 0 0 6px rgba(70,149,103,0.8);
  z-index: 20;
  pointer-events: none;
}