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

:root {
  --ink: #17211f;
  --muted: #71807c;
  --line: #dfe7e3;
  --paper: #f7faf8;
  --panel: #ffffff;
  --green: #2d9d6e;
  --green-dark: #197a53;
  --yellow: #e69322;
  --red: #df5858;
  --grid-sub: #f0f5f2;
  --grid-main: #e2eae6;
  --axis: #7a8e87;
  --canvas-bg: #fbfdfc;
  --tooltip-bg: rgba(23, 33, 31, 0.9);
}

body.dark {
  --ink: #e6f0ed;
  --muted: #93a4a0;
  --line: #293834;
  --paper: #101615;
  --panel: #16201e;
  --green: #48c48f;
  --green-dark: #5ee0a8;
  --grid-sub: #172220;
  --grid-main: #23312d;
  --axis: #5d756d;
  --canvas-bg: #121918;
  --tooltip-bg: rgba(230, 240, 237, 0.95);
}

* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 14px Manrope, -apple-system, BlinkMacSystemFont, Arial, sans-serif;
  letter-spacing: 0;
}

/* Topbar */
.topbar {
  height: 60px;
  border-bottom: 1px solid var(--line);
  background: var(--panel);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 20px;
}
.brand { display: flex; align-items: center; gap: 12px; }
.brand-mark {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  background: var(--ink);
  color: var(--green);
  display: grid;
  place-items: center;
  font: 22px Georgia, serif;
}
body.dark .brand-mark { background: #243531; color: var(--green); }
.brand strong { display: block; font-size: 15px; letter-spacing: 0.3px; }
.brand span, .eyebrow { display: block; color: var(--muted); font: 10px 'DM Mono', monospace; letter-spacing: 1.5px; }

.top-actions { display: flex; gap: 8px; }
.icon-button {
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--ink);
  border-radius: 7px;
  padding: 0 12px;
  height: 34px;
  font: 12px 'DM Mono', monospace;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  transition: 0.15s;
}
.icon-button:hover { border-color: var(--green); color: var(--green-dark); }

/* App shell */
.app-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 430px;
  height: calc(100vh - 60px);
}
.workspace {
  display: flex;
  flex-direction: column;
  min-width: 0;
  position: relative;
}

/* 手動縮放與座標軸範圍工具列 */
.window-bar {
  background: var(--panel);
  border-bottom: 1px solid var(--line);
  padding: 8px 16px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
  font-size: 12px;
}
.window-bar.hidden { display: none; }
.wb-section { display: flex; align-items: center; gap: 6px; }
.wb-label {
  font: 11px 'DM Mono', monospace;
  color: var(--muted);
  font-weight: 500;
  white-space: nowrap;
}
.range-pair {
  display: flex;
  align-items: center;
  gap: 4px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 2px 6px;
}
.range-sep { color: var(--muted); font-size: 11px; }
.range-input {
  width: 65px;
  border: 0;
  background: transparent;
  font: 12px 'DM Mono', monospace;
  color: var(--ink);
  outline: 0;
  text-align: center;
  padding: 3px 0;
}
.range-input:focus { color: var(--green-dark); font-weight: bold; }

/* 縮放 Slider */
.slider-wrap {
  display: flex;
  align-items: center;
  gap: 4px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 2px 8px;
}
.zoom-btn {
  border: 0;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  font-size: 14px;
  padding: 0 4px;
  line-height: 1;
}
.zoom-btn:hover { color: var(--green-dark); }
#zoomSlider {
  width: 80px;
  cursor: pointer;
  accent-color: var(--green);
}

/* 預設按鈕 */
.preset-group { display: flex; gap: 4px; flex-wrap: wrap; }
.preset-btn {
  border: 1px solid var(--line);
  background: var(--paper);
  color: var(--ink);
  border-radius: 5px;
  padding: 3px 8px;
  font: 11px 'DM Mono', monospace;
  cursor: pointer;
  white-space: nowrap;
  transition: 0.15s;
}
.preset-btn:hover {
  border-color: var(--green);
  color: var(--green-dark);
  background: var(--panel);
}

/* 畫布區 */
.plot-wrap {
  position: relative;
  flex: 1;
  min-height: 380px;
  background: var(--canvas-bg);
  overflow: hidden;
  touch-action: none;
}
.plot-wrap canvas {
  display: block;
  width: 100%;
  height: 100%;
  cursor: crosshair;
}

/* 畫布浮動按鈕 */
.plot-toolbar {
  position: absolute;
  top: 14px;
  right: 14px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  z-index: 10;
}
.plot-toolbar button {
  width: 34px;
  height: 34px;
  font-size: 18px;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--ink);
  border-radius: 7px;
  cursor: pointer;
  display: grid;
  place-items: center;
  box-shadow: 0 2px 6px rgba(0,0,0,0.06);
  transition: 0.15s;
}
.plot-toolbar button:hover {
  border-color: var(--green);
  color: var(--green-dark);
}

/* 座標浮動提示 */
.hover-tooltip {
  position: absolute;
  display: none;
  background: var(--tooltip-bg);
  color: #ffffff;
  border-radius: 5px;
  padding: 4px 8px;
  font: 11px 'DM Mono', monospace;
  pointer-events: none;
  transform: translate(-50%, -130%);
  white-space: nowrap;
  z-index: 20;
  box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}
body.dark .hover-tooltip { color: #17211f; }

.axis-readout {
  position: absolute;
  left: 14px;
  bottom: 14px;
  background: rgba(255,255,255,0.85);
  border: 1px solid var(--line);
  border-radius: 5px;
  padding: 4px 8px;
  color: var(--muted);
  font: 11px 'DM Mono', monospace;
  pointer-events: none;
}
body.dark .axis-readout { background: rgba(22, 32, 30, 0.85); }

.bottom-note {
  height: 36px;
  padding: 0 16px;
  border-top: 1px solid var(--line);
  background: var(--panel);
  display: flex;
  align-items: center;
  color: var(--muted);
  font-size: 11px;
}
.live-dot {
  width: 7px;
  height: 7px;
  background: var(--green);
  border-radius: 50%;
  display: inline-block;
  margin-right: 8px;
}
.hint { margin-left: auto; color: var(--muted); }

/* Sidebar */
.sidebar {
  background: var(--panel);
  border-left: 1px solid var(--line);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
}
.sidebar-head {
  padding: 16px 18px 12px;
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
}
.sidebar h1 { font-size: 18px; margin: 4px 0 0; letter-spacing: -0.5px; }
.add-btn {
  width: 30px;
  height: 30px;
  border: 0;
  background: var(--ink);
  color: #ffffff;
  border-radius: 7px;
  font-size: 18px;
  cursor: pointer;
  display: grid;
  place-items: center;
  transition: 0.15s;
}
body.dark .add-btn { background: var(--green); color: #17211f; }
.add-btn:hover { opacity: 0.85; }

/* 快捷符號鍵盤 */
.keypad-panel {
  padding: 0 16px 10px;
  border-bottom: 1px solid var(--line);
}
.keypad-label {
  display: block;
  font: 10px 'DM Mono', monospace;
  color: var(--muted);
  margin-bottom: 6px;
  letter-spacing: 1px;
}
.math-keypad {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 4px;
}
.math-keypad button {
  border: 1px solid var(--line);
  background: var(--paper);
  color: var(--ink);
  border-radius: 5px;
  padding: 6px 2px;
  font: 12px 'DM Mono', monospace;
  cursor: pointer;
  transition: 0.1s;
}
.math-keypad button:hover {
  border-color: var(--green);
  background: var(--panel);
  color: var(--green-dark);
}

/* 函數列表 */
.expressions { padding: 10px 16px; }
.expr-row {
  display: grid;
  grid-template-columns: 20px minmax(0, 1fr) 28px 24px 20px;
  align-items: center;
  gap: 6px;
  padding: 8px 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  margin-bottom: 8px;
  background: var(--panel);
  transition: 0.15s;
}
.expr-row.selected {
  border-color: var(--green);
  box-shadow: 0 0 0 3px rgba(45, 157, 110, 0.15);
}
.expr-num {
  font: 12px 'DM Mono', monospace;
  color: var(--muted);
  text-align: center;
}
.expr-main {
  display: flex;
  flex-direction: column;
  gap: 4px;
  min-width: 0;
}
/* Visual LaTeX math formula preview */
.expr-render {
  font-size: 15px;
  color: var(--ink);
  min-height: 24px;
  display: flex;
  align-items: center;
  overflow-x: auto;
  padding: 2px 0;
}
.expr-render .katex {
  font-size: 1.05em;
}
.expr-input {
  width: 100%;
  border: 0;
  border-top: 1px dashed var(--line);
  outline: 0;
  font: 13px 'DM Mono', monospace;
  color: var(--muted);
  background: transparent;
  padding: 4px 0 2px;
}
.expr-input:focus {
  color: var(--ink);
  border-top-color: var(--green);
}
.expr-input::placeholder { color: #a7b2ae; }

/* 顏色選擇器與色塊 */
.color-picker-wrap {
  position: relative;
  width: 26px;
  height: 26px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  border-radius: 50%;
  transition: 0.15s;
}
.color-picker-wrap:hover {
  background: rgba(45, 157, 110, 0.1);
}
.color-dot {
  width: 16px;
  height: 16px;
  border-radius: 50%;
  border: 2px solid #ffffff;
  box-shadow: 0 0 0 1px var(--line);
  pointer-events: none;
  transition: transform 0.1s;
}
body.dark .color-dot { border-color: #243531; }
.color-picker-wrap:hover .color-dot {
  transform: scale(1.15);
}
.color-picker-input {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  cursor: pointer;
  border: 0;
  padding: 0;
}

/* 顯示/隱藏切換 */
.vis-btn {
  border: 0;
  background: none;
  color: var(--muted);
  cursor: pointer;
  font-size: 14px;
  padding: 2px;
  line-height: 1;
  transition: 0.15s;
}
.vis-btn:hover { color: var(--ink); }
.vis-btn.hidden { opacity: 0.3; }

.delete-btn {
  border: 0;
  background: none;
  color: #a7b2ae;
  cursor: pointer;
  font-size: 18px;
  line-height: 1;
  padding: 0;
}
.delete-btn:hover { color: var(--red); }

.input-hint {
  padding: 0 18px 10px;
  color: var(--muted);
  font-size: 10px;
  line-height: 1.5;
}
.input-hint code {
  font: 10px 'DM Mono', monospace;
  color: var(--green-dark);
  background: var(--paper);
  padding: 1px 4px;
  border-radius: 3px;
}

/* 符號工具區 (求導 / 不定積分) */
.tools-section {
  padding: 14px 18px;
  border-top: 1px solid var(--line);
  margin-top: auto;
}
.tool-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin-top: 8px;
}
.tool-card {
  text-align: left;
  border: 1px solid var(--line);
  background: var(--paper);
  border-radius: 7px;
  padding: 9px 11px;
  cursor: pointer;
  color: var(--ink);
  transition: 0.15s;
}
.tool-card:hover {
  border-color: var(--green);
  background: rgba(45, 157, 110, 0.08);
}
.tool-icon {
  display: block;
  font: 15px Georgia, serif;
  color: var(--green-dark);
  height: 18px;
}
.tool-card strong { font-size: 12px; display: block; }
.tool-card small { display: block; color: var(--muted); font-size: 10px; margin-top: 2px; }

/* 運算結果區 */
.result-box {
  margin-top: 10px;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 12px;
  min-height: 90px;
  background: var(--paper);
  display: flex;
  flex-direction: column;
}
.result-label { font: 10px 'DM Mono', monospace; color: var(--muted); letter-spacing: 1.2px; }
.result-placeholder { font-size: 12px; color: var(--muted); margin-top: 6px; }
.result-render {
  margin-top: 6px;
  font-size: 16px;
  color: var(--green-dark);
  overflow-x: auto;
  padding: 4px 0;
}
.result-render .katex {
  font-size: 1.1em;
}
.result-raw {
  font: 11px 'DM Mono', monospace;
  color: var(--muted);
  margin-top: 4px;
  word-break: break-all;
}
.result-error { color: var(--red); font-size: 12px; margin-top: 6px; }
.add-result-btn {
  margin-top: 10px;
  align-self: flex-start;
  border: 1px solid var(--green);
  background: var(--panel);
  color: var(--green-dark);
  padding: 4px 10px;
  border-radius: 5px;
  font: 11px 'DM Mono', monospace;
  cursor: pointer;
  transition: 0.15s;
}
.add-result-btn:hover {
  background: var(--green);
  color: #ffffff;
}

.sidebar-footer {
  border-top: 1px solid var(--line);
  padding: 12px 18px;
  display: flex;
  justify-content: space-between;
  color: var(--muted);
  font: 9px 'DM Mono', monospace;
  letter-spacing: 1px;
}
.status { color: var(--green-dark); display: flex; align-items: center; }
.status i {
  width: 7px;
  height: 7px;
  background: var(--green);
  border-radius: 50%;
  display: inline-block;
  margin-right: 6px;
}

@media (max-width: 900px) {
  .app-shell { grid-template-columns: 1fr; height: auto; }
  .plot-wrap { height: 48vh; min-height: 320px; }
  .sidebar { border-left: 0; border-top: 1px solid var(--line); }
  .topbar { padding: 0 14px; }
  .hint { display: none; }
  .window-bar { gap: 8px; }
}