/* ==========================================================================
   TTS Matematika - Responsive Design System
   Modes supported: Mode IFP, Mode Desktop, Mode Tablet, Mode Mobile
   ========================================================================== */

*, *::before, *::after { box-sizing: border-box; }
html {
  height: 100%;
  color-scheme: light;
  -webkit-text-size-adjust: 100%;
}
body {
  margin: 0;
  min-height: 100%;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.4;
  padding-inline: 16px;
  padding-block: 16px 36px;
  touch-action: manipulation;
}
[hidden] { display: none !important; }

/* --------------------------------------------------------------------------
   Design Tokens & Variables
   -------------------------------------------------------------------------- */
:root {
  /* Color Palette */
  --paper: #e4dbc1;
  --panel: #eee7d0;
  --ink: #1d1b16;
  --muted: #5f5a47;
  --line: #2c2a22;
  --cell-blank: #f5f0de;
  --cell-given: #d6ccae;
  --cell-rel: #e3ecf2;
  --given-rel: #c5cbc2;
  --accent: #0e4f87;
  --accent-fg: #f7f2e2;
  --accent-soft: rgba(14, 79, 135, 0.18);
  --good: #1f7a37;
  --good-soft: rgba(31, 122, 55, 0.14);
  --bad: #b3261e;
  --bad-soft: rgba(179, 38, 30, 0.14);
  --hint: #8a5a00;
  --heart: #800020;
  --shade: rgba(60, 52, 30, 0.10);
  --shade2: rgba(60, 52, 30, 0.06);
  --overlay: rgba(20, 18, 12, 0.65);

  /* Typography */
  --font-display: 'Bricolage Grotesque', 'Trebuchet MS', system-ui, sans-serif;
  --font-body: 'Lexend', 'Segoe UI', system-ui, sans-serif;

  /* Responsive Sizing Tokens (Desktop Defaults) */
  --wrap-max-width: 1080px;
  --board-max-size: min(650px, calc(100dvh - 190px));
  --btn-height: 46px;
  --key-height: 48px;
  --chip-size: 48px;
  --line-width: 1px;
  --board-border-width: 1px;
  --cell-font-size: clamp(12px, 3.8cqw, 24px);
  --panel-width: 340px;
}

/* Dark Mode (System & Manual) */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #171a1e; --panel: #1f2328; --ink: #ebe6d4; --muted: #a8a38f; --line: #8c8873;
    --cell-blank: #262b31; --cell-given: #121417; --cell-rel: #2c3a47; --given-rel: #1a2530;
    --accent: #80c4ff; --accent-fg: #0a1826; --accent-soft: rgba(128, 196, 255, 0.22);
    --good: #74d38d; --good-soft: rgba(116, 211, 141, 0.16);
    --bad: #ff8f86; --bad-soft: rgba(255, 143, 134, 0.18);
    --hint: #e6b655; --heart: #b3294a; --shade: rgba(255, 255, 255, 0.04); --shade2: rgba(255, 255, 255, 0.025);
    --overlay: rgba(0, 0, 0, 0.75);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #171a1e; --panel: #1f2328; --ink: #ebe6d4; --muted: #a8a38f; --line: #8c8873;
  --cell-blank: #262b31; --cell-given: #121417; --cell-rel: #2c3a47; --given-rel: #1a2530;
  --accent: #80c4ff; --accent-fg: #0a1826; --accent-soft: rgba(128, 196, 255, 0.22);
  --good: #74d38d; --good-soft: rgba(116, 211, 141, 0.16);
  --bad: #ff8f86; --bad-soft: rgba(255, 143, 134, 0.18);
  --hint: #e6b655; --heart: #b3294a; --shade: rgba(255, 255, 255, 0.04); --shade2: rgba(255, 255, 255, 0.025);
  --overlay: rgba(0, 0, 0, 0.75);
  color-scheme: dark;
}

/* --------------------------------------------------------------------------
   MODE IFP (Interactive Flat Panel / Layar Penuh Papan Sentuh Kelas)
   -------------------------------------------------------------------------- */
:root.ifp-mode,
:root:fullscreen {
  --wrap-max-width: 1560px;
  --board-max-size: min(880px, calc(100dvh - 160px));
  --btn-height: 56px;
  --key-height: 66px;
  --chip-size: 56px;
  --line-width: 2px;
  --board-border-width: 2px;
  --cell-font-size: clamp(16px, 3.9cqw, 34px);
  --panel-width: 420px;
  font-size: 17px;
}

:root.ifp-mode body,
:root:fullscreen body {
  padding-inline: 24px;
  padding-block: 16px 28px;
}

/* --------------------------------------------------------------------------
   Base UI Elements
   -------------------------------------------------------------------------- */
button, select {
  font-family: inherit;
  color: inherit;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
}
:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 2px;
}

.shade {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  overflow: hidden;
}
.shade::before {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--shade);
  clip-path: polygon(0 0, 44% 0, 22% 46%, 0 38%);
}
.shade::after {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--shade2);
  clip-path: polygon(100% 30%, 100% 100%, 38% 100%, 56% 62%);
}

.wrap {
  position: relative;
  z-index: 1;
  max-width: var(--wrap-max-width);
  margin-inline: auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
  transition: max-width 0.25s ease;
}

/* --------------------------------------------------------------------------
   Header & Toolbar
   -------------------------------------------------------------------------- */
.top-header {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 16px;
}
.header-left {
  display: inline-flex;
  align-items: center;
  justify-content: flex-start;
}
.header-main {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
}
h1,
.header-main h1 {
  margin: 0;
  font: 700 clamp(1.4rem, 3.8vw, 2.4rem)/1.1 var(--font-display);
  letter-spacing: -0.01em;
  text-wrap: balance;
  text-align: center;
}
.lede {
  margin: 6px auto 0;
  color: var(--muted);
  max-width: 65ch;
  font-size: clamp(0.85rem, 1.6vw, 0.95rem);
  text-align: center;
  text-wrap: pretty;
}
.header-right {
  display: inline-flex;
  align-items: center;
  justify-content: flex-end;
}

.tools {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}
.btn-tool {
  height: 38px;
  padding: 0 12px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: var(--cell-blank);
  color: var(--ink);
  font: 500 0.85rem var(--font-body);
  cursor: pointer;
  transition: transform 0.1s ease, background 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}
.btn-tool:hover {
  background: var(--cell-given);
}
.btn-tool:active {
  transform: translateY(1px);
}
.btn-tool[aria-pressed="true"] {
  background: var(--ink);
  color: var(--paper);
  border-color: var(--ink);
}
.tool-icon {
  width: 1.15rem;
  height: 1.15rem;
  fill: currentColor;
  flex-shrink: 0;
}
.theme-icon-sun { display: block; }
.theme-icon-moon { display: none; }
:root[data-theme="dark"] .theme-icon-sun { display: none; }
:root[data-theme="dark"] .theme-icon-moon { display: block; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .theme-icon-sun { display: none; }
  :root:not([data-theme="light"]) .theme-icon-moon { display: block; }
}
:root[data-theme="light"] .theme-icon-sun { display: block; }
:root[data-theme="light"] .theme-icon-moon { display: none; }

/* --------------------------------------------------------------------------
   Level Bar & Level Selector
   -------------------------------------------------------------------------- */
.levelbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px 16px;
  flex-wrap: wrap;
}
.levels-scroll {
  display: flex;
  align-items: center;
  overflow-x: auto;
  max-width: 100%;
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
  padding-bottom: 2px;
}
.levels-scroll::-webkit-scrollbar { display: none; }

.levels {
  display: flex;
  flex-wrap: nowrap;
  gap: 6px;
}
.chip {
  min-width: var(--chip-size);
  height: var(--chip-size);
  padding: 0 12px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 3px;
  border: var(--line-width) solid var(--line);
  border-radius: 4px;
  background: var(--cell-blank);
  font: 500 1rem/1 var(--font-body);
  cursor: pointer;
  flex-shrink: 0;
  transition: background 0.15s ease, transform 0.1s ease;
}
.chip .st {
  font-size: 0.6rem;
  letter-spacing: 0.06em;
  opacity: 0.8;
}
.chip:hover {
  background: var(--cell-given);
}
.chip[aria-pressed="true"] {
  background: var(--ink);
  color: var(--paper);
  border-color: var(--ink);
}
.chip:active, .btn:active, .key:active {
  transform: translateY(1px);
}

.diff {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--muted);
  font-size: 0.85rem;
  margin-left: auto;
}
.diff select {
  height: 38px;
  padding: 0 10px;
  border: var(--line-width) solid var(--line);
  border-radius: 4px;
  background: var(--cell-blank);
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
}

/* --------------------------------------------------------------------------
   Game Layout (Board + Control Panel)
   -------------------------------------------------------------------------- */
.game {
  display: grid;
  grid-template-columns: minmax(0, 1fr) var(--panel-width);
  gap: 24px 32px;
  align-items: start;
}

/* --------------------------------------------------------------------------
   Board Component
   -------------------------------------------------------------------------- */
.board-col {
  min-width: 0;
  display: flex;
  justify-content: center;
  align-items: flex-start;
}
.board-wrap {
  width: 100%;
  max-width: var(--board-max-size);
  aspect-ratio: 1;
  overflow: auto;
  -webkit-overflow-scrolling: touch;
  overscroll-behavior: contain;
  margin-inline: auto;
}
.board {
  --zoom: 1;
  width: calc(100% * var(--zoom));
  aspect-ratio: 1;
  padding: 1px;
  display: grid;
  grid-template-columns: repeat(13, 1fr);
  grid-template-rows: repeat(13, 1fr);
  container-type: inline-size;
  transition: width 0.2s cubic-bezier(0.2, 0, 0, 1);
}
.cell {
  position: relative;
  margin: -1px 0 0 -1px;
  padding: 0;
  display: grid;
  place-items: center;
  border: var(--board-border-width) solid var(--line);
  border-radius: 0;
  background: var(--cell-given);
  color: var(--ink);
  font: 400 var(--cell-font-size)/1 var(--font-body);
  font-variant-numeric: tabular-nums;
  appearance: none;
  -webkit-appearance: none;
  user-select: none;
  -webkit-user-select: none;
}
button.cell {
  background: var(--cell-blank);
  color: var(--accent);
  font-weight: 500;
  cursor: pointer;
}
button.cell:hover {
  background: var(--cell-rel);
}
.cell.rel {
  background: var(--given-rel);
}
button.cell.rel {
  background: var(--cell-rel);
}
.cell.hinted {
  color: var(--hint);
}
.cell.hinted::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  border-style: solid;
  border-width: 1.7cqw 1.7cqw 0 0;
  border-color: var(--hint) transparent transparent transparent;
}
.cell.ok {
  box-shadow: inset 0 0 0 2px var(--good);
  background: var(--good-soft);
}
.cell.bad {
  box-shadow: inset 0 0 0 2px var(--bad);
  background: var(--bad-soft);
}
.cell.ok::after, .cell.bad::after {
  position: absolute;
  top: 3%;
  right: 7%;
  font-size: 0.72em;
  font-weight: 700;
}
.cell.ok::after { content: '✓'; color: var(--good); }
.cell.bad::after { content: '✗'; color: var(--bad); }

.cell.sel {
  outline: 3px solid var(--accent);
  outline-offset: -3px;
  z-index: 3;
  background: var(--accent-soft);
}
button.cell:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: -3px;
  z-index: 3;
}
.board.done button.cell { cursor: default; }

/* --------------------------------------------------------------------------
   Control Panel & Keypad
   -------------------------------------------------------------------------- */
.panel {
  display: flex;
  flex-direction: column;
  gap: 14px;
  min-width: 0;
}
.panel-head h2 {
  margin: 0;
  font: 700 1.25rem/1.2 var(--font-display);
}
.panel-head h2 span {
  color: var(--muted);
  font: 400 0.85rem var(--font-body);
  margin-left: 8px;
}

.stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  margin: 0;
  padding: 10px 0;
  border-block: var(--line-width) solid var(--line);
}
.stats dt {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
}
.stats dd {
  margin: 2px 0 0;
  font: 500 1.35rem/1.2 var(--font-body);
  font-variant-numeric: tabular-nums;
}

.actions {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
}
.btn {
  height: var(--btn-height);
  padding: 0 10px;
  border: var(--line-width) solid var(--line);
  border-radius: 4px;
  background: transparent;
  font: 500 0.9rem var(--font-body);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  transition: background 0.15s ease, border-color 0.15s ease, transform 0.1s ease;
}
.btn:hover {
  background: var(--cell-blank);
}
.btn.primary {
  background: var(--accent);
  color: var(--accent-fg);
  border-color: var(--accent);
}
.btn.primary:hover {
  opacity: 0.94;
}
.btn-icon {
  width: 1.15em;
  height: 1.15em;
  fill: currentColor;
  flex-shrink: 0;
}

.msg {
  margin: 0;
  min-height: 2.8em;
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.35;
}
.msg.good { color: var(--good); font-weight: 500; }
.msg.bad { color: var(--bad); font-weight: 500; }

.keypad-wrap {
  background: var(--paper);
}
.keypad {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 6px;
}
.key {
  height: var(--key-height);
  border: var(--line-width) solid var(--line);
  border-radius: 4px;
  background: var(--cell-blank);
  font: 500 1.3rem/1 var(--font-body);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.12s ease, transform 0.08s ease;
}
.key:hover:not(:disabled) {
  background: var(--cell-given);
}
.key.op { background: var(--cell-given); }
.key.op:hover:not(:disabled) { filter: brightness(0.95); }
.key.del { font-size: 1.15rem; }
.key:disabled {
  opacity: 0.35;
  cursor: default;
}

/* --------------------------------------------------------------------------
   Modal Selesai (Win Screen)
   -------------------------------------------------------------------------- */
.win {
  position: fixed;
  inset: 0;
  z-index: 50;
  display: grid;
  place-items: center;
  padding: 16px;
  background: var(--overlay);
  backdrop-filter: blur(4px);
}
.win[hidden] { display: none; }
.win-card {
  width: 100%;
  max-width: 400px;
  padding: 28px;
  background: var(--panel);
  border: var(--line-width) solid var(--line);
  border-radius: 6px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.25);
}
.win-card h2 {
  margin: 0;
  font: 700 2rem/1.1 var(--font-display);
}
.win-stars {
  display: flex;
  gap: 6px;
  margin: 14px 0 10px;
}
.win-stars svg {
  width: 38px;
  height: 38px;
  fill: none;
  stroke: var(--ink);
  stroke-width: 1.5;
  stroke-linejoin: round;
}
.win-stars svg.on {
  fill: var(--accent);
  stroke: var(--accent);
}
.win-card dl {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 6px 16px;
  margin: 0 0 20px;
  font-size: 0.95rem;
}
.win-card dt { color: var(--muted); }
.win-card dd { margin: 0; font-variant-numeric: tabular-nums; font-weight: 500; }
.win-actions { display: grid; gap: 8px; }

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */
.foot {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 0.4em;
  padding-top: 14px;
  border-top: var(--line-width) solid var(--line);
  color: var(--muted);
  font-size: 0.85rem;
}
.heart {
  width: 1.2em;
  height: 1.2em;
  fill: var(--heart);
  flex: none;
  transform-origin: center;
  animation: beat 1.3s ease-in-out infinite;
}
@keyframes beat {
  0%, 100% { transform: scale(1); }
  14% { transform: scale(1.22) rotate(-6deg); }
  28% { transform: scale(1); }
  42% { transform: scale(1.18) rotate(6deg); }
  60% { transform: scale(1); }
}

/* ==========================================================================
   RESPONSIVE BREAKPOINTS (Tablet, Mobile, IFP)
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. MODE TABLET (Portrait: 601px - 880px)
   -------------------------------------------------------------------------- */
@media (min-width: 601px) and (max-width: 880px) {
  .game {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
  }
  .board-col {
    width: 100%;
    display: flex;
    justify-content: center;
  }
  .board-wrap {
    max-width: min(540px, 90vw);
  }
  .panel {
    width: 100%;
    max-width: 540px;
    gap: 12px;
  }
  .actions {
    grid-template-columns: repeat(4, 1fr);
  }
  .btn {
    height: 48px;
    font-size: 0.95rem;
  }
  .keypad-wrap {
    width: 100%;
  }
  .keypad {
    gap: 8px;
  }
  .key {
    height: 52px;
    font-size: 1.35rem;
  }
}

/* --------------------------------------------------------------------------
   2. MODE MOBILE (Portrait: <= 600px)
   -------------------------------------------------------------------------- */
@media (max-width: 600px) {
  body {
    padding-inline: 12px;
    padding-block: 10px calc(80px + env(safe-area-inset-bottom, 0px));
  }
  .wrap {
    gap: 12px;
  }
  .top-header {
    grid-template-columns: 1fr 1fr;
    grid-template-areas:
      "left right"
      "main main";
    gap: 10px;
    align-items: center;
  }
  .header-left {
    grid-area: left;
    justify-content: flex-start;
  }
  .header-right {
    grid-area: right;
    justify-content: flex-end;
  }
  .header-main {
    grid-area: main;
    text-align: center;
  }
  .header-main h1 {
    font-size: clamp(1.35rem, 5.6vw, 1.75rem);
    text-align: center;
  }
  .lede {
    font-size: 0.82rem;
    line-height: 1.35;
    text-align: center;
    margin-inline: auto;
  }

  .levelbar {
    gap: 8px;
  }
  .levels-scroll {
    flex: 1 1 auto;
  }
  .chip {
    min-width: 44px;
    height: 44px;
    padding: 0 8px;
    font-size: 0.9rem;
  }
  .diff {
    font-size: 0.8rem;
  }
  .diff select {
    height: 36px;
    font-size: 0.85rem;
  }

  .game {
    display: flex;
    flex-direction: column;
    align-items: stretch;
    gap: 10px;
  }
  .board-wrap {
    width: 100%;
    max-width: 100%;
    border-radius: 4px;
  }

  .panel {
    display: contents;
  }
  .panel-head {
    order: 1;
  }
  .stats {
    order: 2;
    padding: 8px 0;
  }
  .stats dt {
    font-size: 0.65rem;
  }
  .stats dd {
    font-size: 1.2rem;
  }
  .actions {
    order: 3;
    grid-template-columns: repeat(4, 1fr);
    gap: 6px;
  }
  .btn {
    height: 44px;
    padding: 0 4px;
    font-size: 0.78rem;
    flex-direction: column;
    gap: 2px;
  }
  .btn-icon {
    width: 1.1em;
    height: 1.1em;
  }
  .msg {
    order: 4;
    min-height: 2em;
    font-size: 0.85rem;
  }

  /* Keypad menempel di bawah (sticky) dengan safe area */
  .keypad-wrap {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 25;
    padding: 8px 12px calc(8px + env(safe-area-inset-bottom, 0px));
    background: var(--paper);
    border-top: var(--line-width) solid var(--line);
    box-shadow: 0 -4px 16px rgba(0, 0, 0, 0.12);
  }
  .keypad {
    max-width: 440px;
    margin-inline: auto;
    gap: 5px;
  }
  .key {
    height: 46px;
    font-size: 1.25rem;
  }

  .foot {
    order: 10;
    margin-bottom: 20px;
  }
}

/* --------------------------------------------------------------------------
   3. MODE MOBILE LANDSCAPE (Short screens: orientation landscape & height <= 540px)
   -------------------------------------------------------------------------- */
@media (orientation: landscape) and (max-height: 540px) {
  body {
    padding-inline: 14px;
    padding-block: 8px 16px;
  }
  .wrap {
    gap: 8px;
  }
  .top-header {
    grid-template-columns: 1fr auto 1fr;
    align-items: center;
    gap: 12px;
  }
  .header-main h1 {
    font-size: 1.25rem;
  }
  .lede {
    display: none;
  }
  .btn-tool {
    height: 32px;
    padding: 0 8px;
    font-size: 0.78rem;
  }
  .levelbar {
    gap: 6px;
  }
  .chip {
    min-width: 38px;
    height: 38px;
    font-size: 0.85rem;
  }
  .diff select {
    height: 32px;
    font-size: 0.8rem;
  }

  .game {
    display: grid !important;
    grid-template-columns: minmax(0, auto) minmax(280px, 1fr) !important;
    gap: 16px !important;
    align-items: start;
  }
  .board-col {
    display: flex;
    justify-content: center;
  }
  .board-wrap {
    max-width: min(78dvh, 46vw);
    aspect-ratio: 1;
  }
  .panel {
    display: flex !important;
    flex-direction: column;
    gap: 8px;
    max-height: calc(100dvh - 90px);
    overflow-y: auto;
  }
  .stats {
    padding: 4px 0;
  }
  .stats dd {
    font-size: 1.1rem;
  }
  .actions {
    grid-template-columns: repeat(4, 1fr);
    gap: 4px;
  }
  .btn {
    height: 36px;
    padding: 0 6px;
    font-size: 0.78rem;
    flex-direction: row;
  }
  .keypad-wrap {
    position: static !important;
    padding: 0 !important;
    box-shadow: none !important;
    border-top: none !important;
  }
  .keypad {
    gap: 4px;
  }
  .key {
    height: 38px;
    font-size: 1.15rem;
  }
  .foot {
    display: none;
  }
}

/* --------------------------------------------------------------------------
   4. EXTRA LARGE IFP / 4K DISPLAY ENHANCEMENTS
   -------------------------------------------------------------------------- */
@media (min-width: 1600px) and (min-height: 900px) {
  :root:not(.ifp-mode) {
    --wrap-max-width: 1360px;
    --board-max-size: min(760px, calc(100dvh - 200px));
    --panel-width: 380px;
    --btn-height: 50px;
    --key-height: 56px;
    --chip-size: 52px;
  }
}

/* Reduced motion preference */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    transition: none !important;
    animation: none !important;
  }
}