@font-face {
  font-family: 'Ubuntu';
  src: url('/storage/fonts/ubuntu/Ubuntu.woff2') format('woff2'),
       url('/storage/fonts/ubuntu/Ubuntu.woff') format('woff'),
       url('/storage/fonts/ubuntu/Ubuntu.ttf') format('truetype'),
       url('/storage/fonts/ubuntu/Ubuntu.otf') format('otf');
}

:root {
  --bg: #15181f;
  --panel: #1c2029;
  --panel-border: #2a2f3a;
  --font: #e7e9ee;
  --muted: #9aa2b1;
  --accent: #2d70b3;
  --input-bg: #22262f;
  --error: #e05a5a;
}

body.light-theme {
  --bg: #ffffff;
  --panel: #f7f7f8;
  --panel-border: #e2e2e2;
  --font: #1a1a1a;
  --muted: #5c5c5c;
  --accent: #2d70b3;
  --input-bg: #ffffff;
  --error: #c0392b;
}

*,
*::before,
*::after {
  box-sizing: border-box;
  padding: 0;
  margin: 0;
}

html, body {
  height: 100%;
}

body {
  background-color: var(--bg);
  color: var(--font);
  font-family: 'Ubuntu', sans-serif;
  line-height: 1.4;
  overflow: hidden;
}

button {
  border: none;
  color: inherit;
  font-family: inherit;
  font-size: inherit;
  cursor: pointer;
  outline: none;
  background: none;
}

/* APP LAYOUT */

.app {
  display: flex;
  height: 100vh;
  width: 100vw;
}

.sidebar {
  width: 320px;
  min-width: 260px;
  max-width: 40vw;
  background-color: var(--panel);
  border-right: 1px solid var(--panel-border);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.sidebar-header {
  padding: 14px 16px;
  border-bottom: 1px solid var(--panel-border);
  font-weight: bold;
  font-size: 16px;
}

.expression-list {
  flex: 1;
  overflow-y: auto;
  padding: 6px;
}

.add-expression {
  padding: 12px 16px;
  text-align: left;
  color: var(--accent);
  font-weight: bold;
  border-top: 1px solid var(--panel-border);
}

.add-expression:hover {
  background-color: var(--input-bg);
}

/* EXPRESSION ROWS */

.expr-row {
  border-bottom: 1px solid var(--panel-border);
  padding: 6px 4px;
}

.expr-row.has-error .expr-input {
  border-color: var(--error);
}

.expr-main {
  display: flex;
  align-items: center;
  gap: 8px;
}

.color-swatch {
  width: 16px;
  height: 16px;
  min-width: 16px;
  border-radius: 50%;
  border: 2px solid;
}

.expr-input {
  flex: 1;
  min-width: 0;
  background-color: var(--input-bg);
  border: 1px solid var(--panel-border);
  border-radius: 4px;
  color: var(--font);
  padding: 6px 8px;
  font-size: 15px;
  font-family: 'Ubuntu', monospace;
}

.expr-input:focus {
  border-color: var(--accent);
}

.expr-delete {
  color: var(--muted);
  font-size: 16px;
  padding: 2px 6px;
  border-radius: 4px;
}

.expr-delete:hover {
  color: var(--error);
  background-color: var(--input-bg);
}

.expr-error {
  font-size: 11px;
  color: var(--error);
  padding: 2px 4px 0 26px;
}

/* SLIDERS */

.slider-wrap {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 6px 4px 2px 26px;
}

.slider-play {
  font-size: 12px;
  color: var(--accent);
  min-width: 18px;
}

.slider-bound {
  width: 42px;
  background-color: var(--input-bg);
  border: 1px solid var(--panel-border);
  border-radius: 3px;
  color: var(--font);
  font-size: 11px;
  padding: 2px 3px;
}

.slider-range {
  flex: 1;
  accent-color: var(--accent);
}

.slider-value {
  font-size: 12px;
  color: var(--muted);
  min-width: 40px;
  text-align: right;
}

/* KEYPAD */

.keypad {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 4px;
  padding: 8px;
  border-top: 1px solid var(--panel-border);
}

.keypad button {
  background-color: var(--input-bg);
  border: 1px solid var(--panel-border);
  border-radius: 4px;
  padding: 8px 4px;
  font-size: 13px;
}

.keypad button:hover {
  background-color: var(--panel-border);
}

/* GRAPH AREA */

.graph-area {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.toolbar {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 6px 10px;
  background-color: var(--panel);
  border-bottom: 1px solid var(--panel-border);
}

.toolbar button {
  padding: 6px 10px;
  border-radius: 4px;
  font-size: 15px;
}

.toolbar button:hover,
.toolbar button.active {
  background-color: var(--input-bg);
}

.toolbar-spacer {
  flex: 1;
}

.canvas-wrap {
  flex: 1;
  position: relative;
  min-height: 0;
}

#graphCanvas {
  display: block;
  width: 100%;
  height: 100%;
}

/* HELP PANEL */

.help-panel {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 20;
}

.help-panel.open {
  display: flex;
}

.help-content {
  background-color: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 8px;
  padding: 24px;
  max-width: 420px;
  position: relative;
}

.help-content h2 {
  margin-bottom: 12px;
}

.help-content ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
  font-size: 14px;
}

.help-content code {
  background-color: var(--input-bg);
  padding: 1px 5px;
  border-radius: 3px;
}

.close-help {
  position: absolute;
  top: 10px;
  right: 14px;
  font-size: 20px;
  color: var(--muted);
}

/* TOAST */

.toast {
  position: fixed;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background-color: var(--accent);
  color: #fff;
  padding: 10px 18px;
  border-radius: 6px;
  font-size: 14px;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s, transform 0.2s;
  z-index: 30;
}

.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* Disables input spinners */
input[type='number']::-webkit-inner-spin-button,
input[type='number']::-webkit-outer-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

@media (max-width: 700px) {
  .app {
    flex-direction: column;
  }
  .sidebar {
    width: 100%;
    max-width: 100%;
    height: 45vh;
  }
  .graph-area {
    height: 55vh;
  }
}