:root {
  color-scheme: dark;
  font-family: Inter, "Noto Sans JP", system-ui, sans-serif;
  background: #0d1020;
  color: #f7f8ff;
}

* { box-sizing: border-box; }

body {
  min-height: 100vh;
  margin: 0;
  display: grid;
  place-items: center;
  padding: 24px;
  background:
    radial-gradient(circle at 20% 20%, #6136c955, transparent 35%),
    radial-gradient(circle at 80% 80%, #15b8a655, transparent 35%),
    #0d1020;
}

.timer-card {
  width: min(100%, 520px);
  padding: 42px;
  text-align: center;
  border: 1px solid #ffffff1f;
  border-radius: 28px;
  background: #171a2ccc;
  box-shadow: 0 24px 70px #00000066;
  backdrop-filter: blur(16px);
}

.eyebrow {
  margin: 0;
  color: #8cecdf;
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0.22em;
}

h1 { margin: 8px 0 26px; font-size: clamp(1.5rem, 5vw, 2rem); }

.display {
  margin-bottom: 28px;
  font-variant-numeric: tabular-nums;
  font-size: clamp(4rem, 18vw, 7rem);
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.06em;
}

.time-inputs {
  display: flex;
  justify-content: center;
  gap: 14px;
  margin-bottom: 24px;
}

label { display: grid; gap: 7px; color: #b9bed2; font-size: 0.85rem; }

input {
  width: 90px;
  padding: 10px 12px;
  border: 1px solid #ffffff25;
  border-radius: 12px;
  background: #0c0f1dcc;
  color: inherit;
  font: inherit;
  text-align: center;
}

.controls { display: flex; justify-content: center; flex-wrap: wrap; gap: 10px; }

button {
  min-width: 112px;
  padding: 12px 18px;
  border: 1px solid #ffffff25;
  border-radius: 999px;
  background: #24283d;
  color: inherit;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
  transition: transform 0.15s, background 0.15s;
}

button:hover { transform: translateY(-2px); background: #303650; }
button:focus-visible { outline: 3px solid #8cecdf; outline-offset: 3px; }
button.primary { border: 0; background: #8cecdf; color: #09221f; }
button.primary:hover { background: #b0f7ed; }

.message { min-height: 1.5em; margin: 20px 0 0; color: #ffd479; font-weight: 700; }

@media (max-width: 500px) {
  .timer-card { padding: 34px 20px; }
  button { flex: 1 1 100%; }
}