/* --- GLOBAL AESTHETICS (Dark Gradient Theme) --- */
body {
  font-family: Arial, sans-serif;
  display: flex;
  flex-direction: column;
  align-items: center;
  /* Applied Linear Gradient Background */
  background-color: #0b0c10;
  background-image: linear-gradient(
    135deg,
    #0b0c10 0%,
    #171c26 50%,
    #0b0c10 100%
  );
  color: #e0e0e0; /* Off-white text */
  min-height: 100vh;
  margin: 0;
  padding: 20px;
  position: relative;
  overflow: hidden;
}
h3 {
  color: #7b9ed9; /* Soft Blue Header */
  border-bottom: 1px solid rgba(123, 158, 217, 0.3);
  padding-bottom: 5px;
  margin-top: 0;
}
.main-container {
  display: flex;
  width: 95%;
  max-width: 1400px;
  height: 600px;
  justify-content: space-between;
  align-items: flex-start;
  position: relative;
  transform-style: preserve-3d;
  perspective: 1000px;
}

/* --- Header Status Bar --- */
.status-bar {
  position: absolute;
  top: 20px;
  left: 20px; /* Adjusted position to 20px */
  padding: 15px;
  background-color: rgba(20, 25, 30, 0.9);
  border: 1px solid #333;
  border-radius: 4px;
  z-index: 10;
  width: 200px; /* Consistent width */
  font-size: 14px;
}
.status-bar p {
  margin: 5px 0;
  font-size: 14px;
  color: #b0b0b0;
}

/* --- Color Legend --- */
.legend-container {
  position: absolute;
  top: 20px;
  left: 265px; /* Adjusted position for spacing */
  width: 320px;
  padding: 15px;
  border: 1px solid #333;
  background-color: #202020;
  border-radius: 4px;
  font-size: 14px;
}
.legend-item {
  display: flex;
  align-items: center;
  margin-bottom: 8px;
  color: #dddddd;
}
.legend-color {
  width: 20px;
  height: 20px;
  border: 1px solid #444;
  margin-right: 10px;
  border-radius: 2px;
}
.color-acked {
  background-color: #3f72af; /* Muted Blue */
}
.color-ready {
  background-color: #ffeb3b; /* Muted Yellow */
}
.color-sent {
  background-color: #8bc34a; /* Muted Green */
}
.color-buffered {
  background-color: #ff9800; /* Muted Orange */
}
.color-window {
  border: 2px solid #ffffff;
  background: none;
}

/* --- Channel/Pipe & Router Styling --- */
.channel {
  position: absolute;
  top: 50%;
  left: 15%;
  width: 70%;
  height: 40px;
  transform: translateY(-50%);
  background-color: #333; /* Simple Dark Pipe */
  border: 1px solid #444;
  border-radius: 5px;
  z-index: 1;
}
.router-visual {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 120px;
  height: 60px;
  perspective: 1000px;
  z-index: 2;
}
.router {
  position: absolute;
  width: 100%;
  height: 100%;
  background-color: #424242; /* Medium Gray */
  border-radius: 50%;
  top: 0;
  left: 0;
  transform: rotateX(60deg) rotateZ(45deg);
  box-shadow: 0 0 5px rgba(255, 152, 0, 0.5); /* Subtle orange accent */
  border: 2px solid #ff9800;
}
.router-top {
  background-color: #555;
  border: 2px solid #7b9ed9;
  position: absolute;
  width: 80%;
  height: 80%;
  border-radius: 50%;
  top: 10%;
  left: 10%;
  transform: scaleY(0.5);
}
.router-label {
  color: #7b9ed9;
  font-size: 16px;
  transform: translateY(10px);
  position: absolute;
  width: 100%;
  text-align: center;
  top: 100%;
  left: 0;
}
.router-arrows {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 100%;
  height: 100%;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(2, 1fr);
  gap: 5px;
  align-items: center;
  justify-items: center;
  z-index: 3;
}
.router-arrow {
  width: 20px;
  height: 10px;
  background-color: #8bc34a;
  clip-path: polygon(0% 0%, 75% 0%, 100% 50%, 75% 100%, 0% 100%, 25% 50%);
  filter: drop-shadow(0 0 1px black);
}
.router-arrow:nth-child(1) {
  transform: rotate(0deg);
  margin-left: 10px;
}
.router-arrow:nth-child(2) {
  transform: rotate(90deg);
  margin-top: 5px;
}
.router-arrow:nth-child(3) {
  transform: rotate(180deg);
  margin-right: 10px;
}
.router-arrow:nth-child(4) {
  transform: rotate(-90deg);
  margin-bottom: 5px;
}

/* --- End Nodes (Receiver and Sender) --- */
.node-left,
.node-right {
  position: relative;
  z-index: 3;
}
.laptop-body {
  background-color: #424242; /* Match router base */
  width: 180px;
  height: 100px;
  border-radius: 8px;
  margin-top: 250px;
  border: 1px solid #ff9800;
}
.laptop-screen {
  background-color: #1a1a1a;
  height: 60px;
  border-radius: 5px 5px 0 0;
  border-top: 1px solid #7b9ed9;
}

.sender-info {
  position: absolute;
  bottom: 20px;
  right: 150px;
  text-align: center;
}

/* --- Packet Buffer Styling --- */
.buffer-container {
  position: absolute;
  padding: 8px;
  background-color: rgba(0, 0, 0, 0.5);
  border-radius: 6px;
  border: 1px solid #424242;
  height: 280px;
  display: flex;
  flex-direction: column-reverse;
  /* Added Scrollbar Properties */
  overflow-y: auto;
  overflow-x: hidden;
  flex-shrink: 0;
  top: 320px;
}

#receiver-buffer-vis {
  left: 130px;
}
#sender-buffer-vis {
  right: 100px;
}

.packet {
  width: 50px;
  height: 30px;
  line-height: 30px;
  text-align: center;
  margin: 3px 0;
  font-size: 13px;
  font-weight: bold;
  border-radius: 2px;
  border: 1px solid #333;
  transition: all 0.3s ease;
  flex-shrink: 0;
  color: #121212;
}

/* Pipe Connection Aesthetics */
.pipe-vertical {
  position: absolute;
  background-color: #333;
  width: 40px;
  z-index: 0;
}
#pipe-left {
  left: 110px;
  top: 38%;
  height: 60px;
  transform: translateY(-100%);
}
#pipe-right {
  right: 110px;
  top: 38%;
  height: 60px;
  transform: translateY(-100%);
}

/* --- Packet Status Classes --- */
.packet.acked {
  background-color: #3f72af;
  border-color: #3f72af;
  color: white;
}
.packet.ready {
  background-color: #ffeb3b;
  border-color: #ffeb3b;
}
.packet.sent {
  background-color: #8bc34a;
  border-color: #8bc34a;
}
.packet.buffered {
  background-color: #ff9800;
  border-color: #ff9800;
}
.packet.window-border {
  border: 4px solid blueviolet;
  box-sizing: border-box;
}
.packet.empty-slot {
  background-color: transparent;
  color: rgba(255, 255, 255, 0.4);
  border: 1px dashed rgba(255, 255, 255, 0.4);
  font-style: italic;
}

/* --- ANIMATION PAUSE CLASS --- */
.paused {
  transition: none !important;
  animation-play-state: paused !important;
}

/* --- Controls & Log --- */
/* ADJUSTED Positioning for stacked controls */
.user-controls {
  position: absolute;
  bottom: 110px; /* Place above .controls */
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 20px;
  background: rgba(30, 30, 30, 0.8);
  padding: 10px 20px;
  border-radius: 8px 8px 0 0; /* Rounded top corners */
  border: 5px solid #22445f;
  z-index: 20;
  margin-bottom: 40px;
}
.user-controls label {
  display: block;
  margin-bottom: 5px;
  color: #7b9ed9;
  font-size: 14px;
}
.user-controls input {
  width: 80px;
  padding: 5px;
  border: 1px solid #555;
  background-color: #1a1a1a;
  color: #e0e0e0;
  border-radius: 3px;
}

.controls {
  position: absolute;
  bottom: 50px; /* Lower position */
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  background: rgba(0, 0, 0, 0.4);
  padding: 10px 20px;
  border-radius: 0 0 8px 8px; /* Rounded bottom corners */
  border: 1px solid #333;
  border-top: none;
}
button {
  background: none;
  border: 1px solid #66d9ef;
  cursor: pointer;
  width: 55px;
  height: 55px;
  margin: 0 15px;
  padding: 0;
  border-radius: 4px;
  transition: background-color 0.2s, box-shadow 0.2s, transform 0.1s;
  color: white; /* Button text color is white */
}
button:active {
  transform: scale(0.95);
}
button:hover {
  background-color: rgba(102, 217, 239, 0.1);
  box-shadow: 0 0 8px rgba(102, 217, 239, 0.6);
}
button svg {
  fill: #e0e0e0;
  width: 60%;
  height: 60%;
  margin: 20%;
}
#log-area {
  position: absolute;
  top: 20px;
  right: 20px;
  width: 350px;
  max-height: 200px;
  overflow-y: scroll;
  border: 1px solid #444a57;
  padding: 10px;
  background-color: #1a1a1a;
  color: #8bc34a; /* Green log text */
  font-family: monospace;
  font-size: 12px;
  border-radius: 4px;
  z-index: 10;
}
.log-entry.error {
  color: #ff5252;
}
.log-entry.success {
  color: #66d9ef; /* Cyan for success */
}

/* --- Animated Packet (Simplified for clear, discrete travel) --- */
.animated-packet {
  position: absolute;
  width: 40px;
  height: 30px;
  color: black;
  text-align: center;
  line-height: 30px;
  font-weight: bold;
  border-radius: 3px;
  z-index: 5;
}
.ack-packet {
  background-color: #ff9800;
  border: 2px solid white;
  color: white;
}
.data-packet {
  background-color: #8bc34a;
  color: black;
}