:root {
  --mcu-bg: #e3f2fd;
  --ext-bg: #ffffff;
  --high-color: #ff4444;
  --low-color: #4444ff;
  --hiz-color: #999999;
  --wire-off: #cccccc;
  --wire-on: #333333;
  --arrow-color: #ffd700;
  --logic-bg: #bbdefb;
}

* {
  box-sizing: border-box;
}

body {
  font-family: "Microsoft YaHei", sans-serif;
  background-color: #f0f2f5;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  height: 100vh;
  overflow: hidden;
}

header {
  background-color: #1976d2;
  color: white;
  padding: 15px;
  text-align: center;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  z-index: 10;
}

main {
  display: flex;
  flex: 1;
  overflow: hidden;
}

#sidebar {
  width: 240px;
  background-color: #fff;
  border-right: 1px solid #ddd;
  padding: 15px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  overflow-y: auto;
  box-shadow: 2px 0 5px rgba(0, 0, 0, 0.05);
}

.mode-btn {
  padding: 12px;
  border: 1px solid #1976d2;
  background: white;
  color: #1976d2;
  cursor: pointer;
  border-radius: 6px;
  transition: all 0.2s;
  text-align: left;
  font-weight: bold;
  font-size: 14px;
}

.mode-btn:hover {
  background: #e3f2fd;
}

.mode-btn.active {
  background: #1976d2;
  color: white;
}

#content {
  flex: 1;
  display: flex;
  flex-direction: column;
  padding: 20px;
  background: #f8f9fa;
  position: relative;
}

#canvas-container {
  flex: 1;
  background: white;
  border-radius: 12px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
  overflow: hidden;
  border: 1px solid #eee;
}

#info-panel {
  height: 180px;
  background: white;
  margin-top: 20px;
  padding: 20px;
  border-radius: 12px;
  border-left: 6px solid #1976d2;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.05);
  overflow-y: auto;
}

#info-title {
  margin: 0 0 10px 0;
  color: #1976d2;
  font-size: 18px;
}

#info-text {
  font-size: 15px;
  line-height: 1.6;
  color: #444;
  white-space: pre-line;
  margin: 0;
}

.controls {
  position: absolute;
  bottom: 20px;
  right: 20px;
  display: flex;
  gap: 10px;
}

.ctrl-btn {
  padding: 10px 20px;
  background: #444;
  color: white;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  font-size: 14px;
  transition: background 0.2s;
}

.ctrl-btn:hover {
  background: #222;
}

svg {
  width: 100%;
  height: 100%;
  max-width: 1000px;
}

.mcu-box {
  fill: var(--mcu-bg);
  stroke: #90caf9;
  stroke-width: 2;
}

.ext-label {
  font-size: 16px;
  font-weight: bold;
  fill: #777;
}

.mcu-label {
  font-size: 18px;
  font-weight: bold;
  fill: #1565c0;
}

.wire {
  fill: none;
  stroke: var(--wire-off);
  stroke-width: 3;
  transition: stroke 0.3s;
  stroke-linecap: round;
}

.wire-active {
  stroke: var(--wire-on);
}

.wire-high {
  stroke: var(--high-color);
}

.wire-low {
  stroke: var(--low-color);
}

.wire-hiz {
  stroke: var(--hiz-color);
}

.component {
  fill: white;
  stroke: #333;
  stroke-width: 2;
}

.resistor {
  fill: none;
  stroke: #333;
  stroke-width: 2;
}

.arrow {
  fill: none;
  stroke: var(--arrow-color);
  stroke-width: 4;
  stroke-dasharray: 12, 12;
  visibility: hidden;
  stroke-linecap: round;
}

@keyframes flow {
  to {
    stroke-dashoffset: -24;
  }
}

.flowing {
  visibility: visible;
  animation: flow 0.8s linear infinite;
}

.switch-line {
  stroke: #333;
  stroke-width: 3;
  transition: transform 0.3s;
  transform-origin: center;
}

.switch-closed {
  transform: rotate(-35deg);
}

.pad {
  fill: #ffd54f;
  stroke: #fbc02d;
  stroke-width: 2;
}

.buffer {
  fill: #fff;
  stroke: #333;
  stroke-width: 2;
}

.status-dot {
  transition: fill 0.3s;
}

.high {
  fill: var(--high-color);
}

.low {
  fill: var(--low-color);
}

.hiz {
  fill: var(--hiz-color);
}

.label-text {
  font-size: 13px;
  fill: #333;
  font-weight: 500;
}

.mos-label {
  font-size: 11px;
  fill: #555;
}