/* ===== CSS Custom Properties — Light / Dark ===== */
:root {
  --bg: #f8fafc;
  --bg-card: #ffffff;
  --text: #1e293b;
  --text-muted: #64748b;
  --text-faint: #94a3b8;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-shadow: rgba(37, 99, 235, 0.20);
  --error-bg: #fef2f2;
  --error-border: #fecaca;
  --error-text: #b91c1c;
  --success-bg: #f0fdf4;
  --border: #e2e8f0;
  --toggle-bg: #e2e8f0;
  --toggle-text: #334155;
}

[data-theme="dark"] {
  --bg: #0f172a;
  --bg-card: #1e293b;
  --text: #f1f5f9;
  --text-muted: #94a3b8;
  --text-faint: #64748b;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --accent-shadow: rgba(59, 130, 246, 0.25);
  --error-bg: #1c1017;
  --error-border: #7f1d1d;
  --error-text: #fca5a5;
  --success-bg: #052e16;
  --border: #334155;
  --toggle-bg: #334155;
  --toggle-text: #e2e8f0;
}

/* ===== Reset & Base ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  transition: background 0.3s, color 0.3s;
}

/* ===== Theme Toggle ===== */
.theme-toggle {
  position: fixed;
  top: 1rem;
  right: 1rem;
  background: var(--toggle-bg);
  color: var(--toggle-text);
  border: none;
  border-radius: 9999px;
  width: 2.5rem;
  height: 2.5rem;
  font-size: 1.2rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s;
  z-index: 50;
}
.theme-toggle:hover { opacity: 0.8; }

/* ===== Screens ===== */
.screen { display: none; text-align: center; padding: 0 1.5rem; width: 100%; max-width: 24rem; margin: auto; }
.screen.active { display: block; }

/* ===== Typography ===== */
.heading { font-size: 1.5rem; font-weight: 700; color: var(--text); margin-bottom: 0.25rem; }
.subtext { font-size: 0.875rem; color: var(--text-faint); word-break: break-all; }
.icon-big { font-size: 3.5rem; margin-bottom: 1rem; }

/* ===== Status Spinner ===== */
.status-area { display: none; margin-bottom: 1.5rem; }
.status-area.visible { display: flex; align-items: center; justify-content: center; gap: 0.5rem; }
.status-area .spinner {
  width: 1.25rem; height: 1.25rem;
  border: 3px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
.status-text { font-size: 0.875rem; font-weight: 500; color: var(--text-muted); }

/* ===== Error Box ===== */
.error-box {
  display: none;
  margin-bottom: 1.5rem;
  background: var(--error-bg);
  border: 1px solid var(--error-border);
  border-radius: 0.75rem;
  padding: 0.75rem 1rem;
  font-size: 0.875rem;
  color: var(--error-text);
}
.error-box.visible { display: block; }

/* ===== Buttons ===== */
.btn-primary {
  width: 100%;
  background: var(--accent);
  color: #fff;
  font-weight: 600;
  font-size: 1.125rem;
  border: none;
  border-radius: 1rem;
  padding: 1rem 1.5rem;
  box-shadow: 0 4px 14px var(--accent-shadow);
  cursor: pointer;
  transition: background 0.15s, transform 0.1s;
}
.btn-primary:hover { background: var(--accent-hover); }
.btn-primary:active { transform: scale(0.98); }
.btn-primary:disabled { opacity: 0.5; cursor: not-allowed; transform: none; }

/* ===== Button Group (action select) ===== */
.btn-group { display: flex; flex-direction: column; gap: 0.75rem; }
.btn-select { font-size: 1rem; padding: 0.875rem 1.5rem; }
.btn-secondary {
  background: transparent;
  color: var(--text);
  border: 2px solid var(--border);
  box-shadow: none;
}
.btn-secondary:hover { background: var(--toggle-bg); }

/* ===== Utilities ===== */
.hidden { display: none !important; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-6 { margin-bottom: 1.5rem; }
.mb-8 { margin-bottom: 2rem; }