* { box-sizing: border-box; }
body {
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, sans-serif;
  margin: 0; min-height: 100vh; display: grid; place-items: center;
  background: #0f172a; color: #e2e8f0;
}
/* Light theme overrides */
body.light { background: #f3f4f6; color: #1f2937; }
.card {
  width: 100%; max-width: 420px; padding: 24px; border-radius: 16px;
  background: #111827; box-shadow: 0 20px 40px rgba(0,0,0,0.4);
  border: 1px solid #1f2937;
}
body.light .card { background: #ffffff; border: 1px solid #d1d5db; box-shadow: 0 20px 40px rgba(0,0,0,0.1); }
h1 { margin: 0 0 8px; font-size: 22px; font-weight: 700; }
.timer {
  font-variant-numeric: tabular-nums;
  font-size: 64px; font-weight: 800; letter-spacing: 2px; text-align: center;
  margin: 16px 0 8px;
}
.mode { text-align: center; opacity: 0.85; margin-bottom: 16px; }
.row { display: flex; gap: 12px; margin: 10px 0; }
.row > label { flex: 1; display: grid; gap: 6px; font-size: 14px; }
input[type="number"] {
  width: 100%; padding: 10px 12px; background: #0b1220; color: #e5e7eb;
  border: 1px solid #334155; border-radius: 10px;
}
body.light input[type="number"] { background: #f9fafb; color: #111827; border: 1px solid #d1d5db; }
.buttons { display: flex; gap: 10px; margin-top: 14px; }
button {
  flex: 1; padding: 12px; border-radius: 12px; border: 1px solid #334155;
  background: #0b1220; color: #e5e7eb; font-weight: 600; cursor: pointer;
}
body.light button { background: #e5e7eb; color: #1f2937; border: 1px solid #d1d5db; }
button.primary { background: #2563eb; border-color: #1d4ed8; color: white; }
button:disabled { opacity: 0.6; cursor: not-allowed; }
.theme-toggle { text-align: right; }
.theme-toggle button { flex: none; padding: 6px 10px; border-radius: 8px; font-size: 14px; }
.hint { margin-top: 12px; font-size: 12px; opacity: 0.75; text-align: center; }