:root {
  --bg-1: #f5f7fb;
  --bg-2: #e7edf6;
  --card: #ffffff;
  --ink: #0c1729;
  --muted: #49607e;
  --accent: #0e7490;
  --accent-2: #0f766e;
  --border: #cfdaea;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  height: 100%;
  color: var(--ink);
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background:
    radial-gradient(1000px 600px at 10% -10%, #dbeafe 0%, transparent 65%),
    radial-gradient(1000px 600px at 90% 110%, #dcfce7 0%, transparent 60%),
    linear-gradient(160deg, var(--bg-1), var(--bg-2));
}

.layout {
  min-height: 100%;
  display: grid;
  grid-template-rows: auto 1fr auto;
  max-width: 1400px;
  margin: 0 auto;
  padding: 18px;
  gap: 14px;
}

.topbar {
  background: rgba(255, 255, 255, 0.9);
  border: 1px solid var(--border);
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 14px;
  backdrop-filter: blur(6px);
}

.brand {
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: 0.3px;
}

.controls {
  display: flex;
  align-items: center;
  gap: 10px;
}

.indicator {
  color: var(--muted);
  min-width: 120px;
  text-align: center;
}

.btn {
  border: 1px solid transparent;
  border-radius: 10px;
  padding: 8px 12px;
  color: #fff;
  background: linear-gradient(120deg, var(--accent), var(--accent-2));
  cursor: pointer;
  font-weight: 600;
}

.btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.btn-secondary {
  background: #fff;
  color: var(--ink);
  border-color: var(--border);
}

.viewer-wrap {
  position: relative;
  border-radius: 18px;
  border: 1px solid var(--border);
  background: var(--card);
  padding: 12px;
  display: grid;
  place-items: center;
  min-height: 60vh;
}

.slide-image {
  width: 100%;
  height: 100%;
  max-height: calc(100vh - 220px);
  object-fit: contain;
  border-radius: 12px;
  box-shadow: 0 16px 30px rgba(15, 23, 42, 0.14);
  background: #f9fbff;
}

.status {
  position: absolute;
  bottom: 18px;
  left: 50%;
  transform: translateX(-50%);
  background: rgba(12, 23, 41, 0.85);
  color: #fff;
  padding: 8px 12px;
  border-radius: 10px;
  font-size: 0.95rem;
}

.error {
  background: #c2410c;
}

.hidden {
  display: none;
}

.footer {
  background: rgba(255, 255, 255, 0.9);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 10px 14px;
  display: flex;
  align-items: center;
  gap: 14px;
}

.range {
  width: 100%;
}

.hint {
  color: var(--muted);
  white-space: nowrap;
}

@media (max-width: 800px) {
  .topbar {
    flex-wrap: wrap;
    gap: 10px;
  }

  .controls {
    order: 3;
    width: 100%;
    justify-content: center;
  }

  .indicator {
    min-width: 110px;
  }

  .hint {
    display: none;
  }
}