:root {
  --bg0: #04141e; --bg1: #072a3b; --surface: #f4fafd; --ink: #0a2533;
  --muted: #486575; --line: #d1e5ef; --accent: #179391; --teal: #6ce2d8;
  --green: #10b981; --yellow: #d97706; --red: #ef4444; --radius: 16px;
  --mono: ui-monospace, Cascadia Code, Menlo, Consolas, monospace;
}
* { box-sizing: border-box; }
body {
  margin: 0; color: var(--ink);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, Arial, sans-serif;
  background: linear-gradient(180deg, var(--bg0), var(--bg1));
  min-height: 100vh; display: flex; align-items: center; justify-content: center;
  padding: 16px;
}
.widget-wrap { width: 100%; max-width: 520px; margin: auto; }
.widget {
  background: var(--surface); border-radius: var(--radius);
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.45);
  border: 1px solid rgba(255, 255, 255, 0.2); overflow: hidden;
}
.widget-head {
  display: flex; justify-content: space-between; align-items: center;
  padding: 18px 20px 14px; background: #082d40; color: #eaf7f6; gap: 12px;
}
.title-group h1 { font-size: 1.25rem; margin: 0; font-weight: 700; letter-spacing: -0.01em; }
.title-group .sub { margin: 2px 0 0; font-size: 0.8rem; color: #a8cfdf; }
.units { display: flex; background: rgba(255, 255, 255, 0.14); border-radius: 999px; padding: 3px; }
.units button {
  border: 0; background: transparent; color: #fff; padding: 5px 12px;
  border-radius: 999px; cursor: pointer; font: inherit; font-size: 0.8rem;
  font-weight: 600; transition: background 0.15s, color 0.15s;
}
.units button.on { background: var(--teal); color: var(--bg0); }
.tank-frame { background: #082d40; padding: 0 20px 16px; text-align: center; }
.tank-glass {
  position: relative; height: 150px; border-radius: 0 0 16px 16px; overflow: hidden;
  border: 2px solid rgba(255, 255, 255, 0.45); border-top-width: 4px;
  background: linear-gradient(180deg, rgba(4, 20, 30, 0.6) 0%, rgba(8, 45, 64, 0.4) 100%);
  margin: 0 auto;
}
.water-void {
  position: absolute; left: 0; right: 0; top: 0; height: 25%;
  background: rgba(4, 20, 30, 0.45); border-bottom: 1.5px dashed rgba(255, 255, 255, 0.5);
  display: flex; align-items: center; justify-content: center;
  transition: height 0.18s ease-out; overflow: hidden; z-index: 2;
}
.water-pct {
  color: #cce9f5; font-weight: 700; font-size: 0.85rem; font-family: var(--mono);
  text-shadow: 0 1px 3px rgba(0, 0, 0, 0.8); letter-spacing: 0.02em;
}
.water-body {
  position: absolute; left: 0; right: 0; bottom: 0; height: 75%;
  background: linear-gradient(180deg, #1fa2c2 0%, #0c4d6c 60%, #05293d 100%);
  transition: height 0.18s ease-out; overflow: visible; z-index: 1;
}
.wave {
  position: absolute; top: -12px; left: 0; width: 200%; height: 16px;
  background-repeat: repeat-x; background-size: 80px 16px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 80 16'%3E%3Cpath d='M0 8 Q 20 0 40 8 T 80 8 L 80 16 L 0 16 Z' fill='%236ce2d8' fill-opacity='0.9'/%3E%3C/svg%3E");
  animation: wave-slide 4s linear infinite;
}
.wave.back {
  top: -10px; animation: wave-slide-back 6s linear infinite; opacity: 0.55;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 80 16'%3E%3Cpath d='M0 8 Q 20 16 40 8 T 80 8 L 80 16 L 0 16 Z' fill='%234fbcd4' fill-opacity='0.6'/%3E%3C/svg%3E");
}
@keyframes wave-slide { 0% { transform: translateX(0); } 100% { transform: translateX(-80px); } }
@keyframes wave-slide-back { 0% { transform: translateX(-80px); } 100% { transform: translateX(0); } }
.fish {
  position: absolute; left: 10%; bottom: 20%; font-size: 1.8rem;
  transition: bottom 0.25s ease-out, transform 0.25s ease-out; user-select: none; z-index: 5;
}
.fish.happy { animation: fish-swim 4.5s ease-in-out infinite; }
@keyframes fish-swim {
  0%, 100% { transform: translateX(0) scaleX(-1); } 48% { transform: translateX(180px) scaleX(-1); }
  50% { transform: translateX(180px) scaleX(1); } 98% { transform: translateX(0) scaleX(1); }
}
.fish.alert { animation: fish-dart 2.5s ease-in-out infinite; }
@keyframes fish-dart {
  0%, 100% { transform: translateX(0) scaleX(-1); } 48% { transform: translateX(120px) scaleX(-1); }
  50% { transform: translateX(120px) scaleX(1); } 98% { transform: translateX(0) scaleX(1); }
}
.fish.stressed { animation: fish-panic .5s ease-in-out infinite; filter: drop-shadow(0 0 6px #ef4444); }
@keyframes fish-panic {
  0%, 100% { transform: translateX(20px) rotate(-6deg); }
  50% { transform: translateX(25px) translateY(-4px) rotate(8deg); }
}
.fish.belly-up { top: -12px !important; bottom: auto !important; left: 18% !important; animation: belly-up-surface 2s ease-in-out infinite; filter: grayscale(.5); }
@keyframes belly-up-surface {
  0%, 100% { transform: rotate(180deg) translateY(0); }
  50% { transform: rotate(176deg) translateY(-4px); }
}
.bubbles { position: absolute; inset: 0; overflow: hidden; pointer-events: none; z-index: 1; }
.bubbles i {
  position: absolute; bottom: 4%; width: 6px; height: 6px; border-radius: 50%;
  background: rgba(255, 255, 255, 0.7); box-shadow: 0 0 5px #fff; animation: bubble-rise 2.8s linear infinite;
}
.bubbles i:nth-child(1) { left: 65%; animation-delay: 0s; }
.bubbles i:nth-child(2) { left: 78%; width: 5px; height: 5px; animation-delay: 1.2s; }
.bubbles i:nth-child(3) { left: 88%; width: 8px; height: 8px; animation-delay: 2.1s; }
@keyframes bubble-rise {
  from { transform: translateY(0); opacity: 0; } 10% { opacity: 0.9; } 85% { opacity: 0.9; } to { transform: translateY(-160px); opacity: 0; }
}
.controls { padding: 18px 20px; display: flex; flex-direction: column; gap: 14px; }
.field { display: flex; flex-direction: column; }
.field-head { display: flex; justify-content: space-between; align-items: center; margin-bottom: 6px; }
label { font-weight: 600; font-size: 0.88rem; color: var(--ink); }
.input-row { display: flex; position: relative; align-items: center; }
input[type=number] {
  width: 100%; padding: 8px 64px 8px 12px; border: 1.5px solid var(--line);
  border-radius: 10px; font: inherit; font-family: var(--mono); font-size: 0.95rem;
  color: var(--ink); background: #fff;
}
.unit-badge { position: absolute; right: 12px; font-weight: 700; font-size: 0.82rem; color: var(--muted); pointer-events: none; }
.chips { display: flex; gap: 4px; }
.chips button {
  background: #eaf3f8; border: 1px solid var(--line); border-radius: 999px;
  padding: 2px 7px; font-size: 0.72rem; color: var(--bg1); cursor: pointer;
  font-family: var(--mono); font-weight: 600; transition: background 0.15s, color 0.15s;
}
.chips button:hover { background: var(--bg1); color: #fff; }
input[type=range] { width: 100%; margin: 6px 0 2px; }
#pct.g { accent-color: var(--green); }
#pct.y { accent-color: var(--yellow); }
#pct.r { accent-color: var(--red); }
output { font-family: var(--mono); font-weight: 700; color: var(--bg1); font-size: 0.92rem; }
.slider-bounds { display: flex; justify-content: space-between; font-size: 0.72rem; color: var(--muted); font-weight: 500; }
.grid-two { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.results { background: #eef6fa; border-top: 1px solid var(--line); padding: 18px 20px; text-align: center; }
.volume-display {
  display: flex; justify-content: center; align-items: center; gap: 20px;
  background: #fff; border: 1px solid var(--line); border-radius: 12px;
  padding: 12px 16px; margin-bottom: 12px;
}
.vol-stat { display: flex; flex-direction: column; }
.vol-num { font-size: 1.9rem; font-weight: 800; font-family: var(--mono); color: var(--ink); line-height: 1; }
.vol-label { font-size: 0.75rem; color: var(--muted); margin-top: 4px; font-weight: 600; }
.vol-divider { width: 1px; height: 38px; background: var(--line); }
.bucket-details { margin-bottom: 14px; }
.bucket-math { font-size: 0.95rem; font-weight: 700; color: var(--ink); margin: 0 0 4px; }
.bucket-trips { font-size: 0.82rem; color: var(--muted); margin: 0; }
.health-indicator { margin-top: 10px; }
.badge {
  display: inline-block; padding: 7px 18px; border-radius: 999px;
  color: #fff; font-weight: 700; font-size: 0.88rem; line-height: 1.2;
}
.badge.g { background: var(--green); }
.badge.y { background: var(--yellow); }
.badge.r { background: var(--red); }
.warn-box {
  background: #fef2f2; border: 1.5px solid var(--red); border-radius: 10px;
  padding: 10px 12px; margin: 12px 0 0; font-size: 0.82rem; line-height: 1.4;
  color: #991b1b; text-align: left;
}
.widget-foot {
  padding: 10px 20px; text-align: center; font-size: 0.72rem;
  color: var(--muted); background: #eef6fa; border-top: 1px solid rgba(0, 0, 0, 0.05);
}
input:focus-visible, button:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
@media (prefers-reduced-motion: reduce) {
  .bubbles i, .fish, .water, .wave { animation: none !important; transition: none !important; }
}