:root {
  --bg-top: #16353a;
  --bg-bottom: #0b1519;
  --panel: rgba(12, 25, 29, 0.72);
  --line: rgba(193, 242, 210, 0.22);
  --text-main: #eaf7ec;
  --text-sub: #b8d8c0;
  --accent: #6de2af;
  --accent-2: #f8be6f;
  --danger: #ff8d8d;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  min-height: 100%;
  color: var(--text-main);
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  background:
    radial-gradient(1200px 800px at 10% -20%, rgba(109, 226, 175, 0.22), transparent 55%),
    radial-gradient(900px 700px at 95% 0%, rgba(248, 190, 111, 0.15), transparent 55%),
    linear-gradient(170deg, var(--bg-top), var(--bg-bottom));
}

body {
  min-height: 100dvh;
}

.app-shell {
  max-width: 980px;
  margin: 0 auto;
  padding: max(14px, env(safe-area-inset-top)) 14px max(16px, env(safe-area-inset-bottom));
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 14px;
}

.topbar h1 {
  margin: 0;
  letter-spacing: 0.06em;
  font-size: clamp(1.1rem, 2.8vw, 1.45rem);
  font-weight: 800;
}

.main-layout {
  display: grid;
  grid-template-columns: 1.25fr 1fr;
  gap: 14px;
}

.camera-stage {
  position: relative;
  width: 100%;
  aspect-ratio: 9 / 16;
  overflow: hidden;
  border-radius: 20px;
  border: 1px solid var(--line);
  box-shadow:
    0 10px 24px rgba(0, 0, 0, 0.3),
    inset 0 0 0 1px rgba(255, 255, 255, 0.05);
  background: rgba(0, 0, 0, 0.48);
}

#cameraVideo,
#overlayImage,
.landscape-mask {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

#cameraVideo {
  object-fit: cover;
  background: #000;
  transform: translateZ(0);
}

#overlayImage {
  object-fit: cover;
  pointer-events: none;
  opacity: 0.55;
  display: none;
}

.landscape-mask {
  display: grid;
  place-items: center;
  background: rgba(0, 0, 0, 0.8);
  text-align: center;
  padding: 20px;
}

.landscape-mask p {
  margin: 0;
  color: #fff;
  font-size: 1.05rem;
  line-height: 1.5;
}

.control-panel {
  border: 1px solid var(--line);
  border-radius: 20px;
  background: var(--panel);
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  box-shadow: 0 8px 18px rgba(0, 0, 0, 0.16);
}

.row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.btn {
  border: 1px solid transparent;
  border-radius: 999px;
  padding: 10px 14px;
  font-size: 0.95rem;
  cursor: pointer;
  transition: transform 0.18s ease, border-color 0.18s ease;
}

.btn:active {
  transform: translateY(1px) scale(0.995);
}

.primary {
  color: #0d1f22;
  background: linear-gradient(135deg, var(--accent), #8af6c5);
  box-shadow: 0 8px 20px rgba(109, 226, 175, 0.24);
}

.secondary {
  color: var(--text-main);
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.14);
}

.ghost {
  color: var(--text-sub);
  background: transparent;
  border-color: rgba(255, 255, 255, 0.22);
}

.file-label {
  display: inline-flex;
  align-items: center;
}

#overlayInput {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
}

.slider-wrap {
  display: grid;
  gap: 6px;
}

.slider-wrap label {
  color: var(--text-sub);
  font-size: 0.92rem;
}

#opacityRange {
  width: 100%;
  accent-color: var(--accent-2);
}

#opacityValue {
  justify-self: end;
  color: var(--accent-2);
  font-variant-numeric: tabular-nums;
}

.status {
  margin: 0;
  min-height: 1.4em;
  color: var(--text-sub);
  line-height: 1.5;
}

.status.error {
  color: var(--danger);
}

.status.success {
  color: var(--accent);
}

@media (max-width: 860px) {
  .main-layout {
    grid-template-columns: 1fr;
  }

  .camera-stage {
    aspect-ratio: 3 / 5;
  }
}

@media (orientation: landscape) and (max-width: 1024px) {
  .app-shell {
    padding-top: 8px;
  }

  .topbar {
    margin-bottom: 8px;
  }
}