/* Máy tính khoa học — main styles */
[hidden] { display: none !important; }

.mt-container { max-width: 720px; padding-top: 40px; }

.back-link { display: inline-block; font-size: 0.9rem; color: var(--text-muted); margin-bottom: 24px; transition: color 0.2s ease; }
.back-link:hover { color: var(--accent); }

.mt-hero { margin-bottom: 24px; }
.mt-hero h1 { font-size: clamp(1.8rem, 4vw, 2.6rem); }
.mt-hero .tagline { font-size: 0.95rem; }

.mt-calc {
  background: var(--bg-elev); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 18px; margin-bottom: 18px;
}

/* Display */
.mt-display {
  background: var(--bg); border: 1px solid var(--border);
  border-radius: 10px; padding: 14px 16px; margin-bottom: 14px;
  display: flex; flex-direction: column; gap: 6px; min-height: 110px;
}
.mt-display-meta { display: flex; justify-content: space-between; align-items: center; gap: 8px; }
.mt-meta-pill {
  background: transparent; border: 1px solid var(--border); color: var(--text-muted);
  font: inherit; font-size: 0.72rem; font-weight: 700; letter-spacing: 0.06em;
  padding: 4px 12px; border-radius: 999px; cursor: pointer;
  transition: all 0.15s ease;
}
.mt-meta-pill:hover { color: var(--text); border-color: var(--accent); }
.mt-meta-pill.is-on { color: var(--accent); border-color: var(--accent); background: var(--accent-glow); }
.mt-meta-ans { font-size: 0.78rem; color: var(--text-muted); font-family: 'JetBrains Mono', monospace; }
.mt-meta-ans span { color: var(--text); }

.mt-display-expr {
  font-family: 'JetBrains Mono', monospace; font-size: 1.4rem;
  text-align: right; word-break: break-all; line-height: 1.3;
  color: var(--text-muted); flex: 1;
}
.mt-display-result {
  font-family: 'JetBrains Mono', monospace; font-size: 1.6rem; font-weight: 700;
  text-align: right; color: var(--accent); min-height: 1.6em;
}
.mt-error { color: var(--danger); font-size: 1.1rem; }

/* Keypad */
.mt-keypad {
  display: grid; grid-template-columns: repeat(5, 1fr); gap: 6px;
}
.mt-key {
  font: inherit; font-weight: 600; font-size: 0.95rem;
  background: var(--bg); border: 1px solid var(--border); color: var(--text);
  padding: 14px 8px; border-radius: 8px; cursor: pointer;
  transition: transform 0.1s ease, background 0.15s ease, border-color 0.15s ease;
  user-select: none;
}
.mt-key:hover { border-color: var(--accent); background: var(--bg-elev-hover); }
.mt-key:active { transform: translateY(1px); }
.mt-key.mt-num { background: var(--bg-elev); font-size: 1.1rem; }
.mt-key.mt-fn { color: var(--accent); font-size: 0.9rem; }
.mt-key.mt-op { color: var(--warn); font-size: 1.2rem; font-weight: 700; }
.mt-key.mt-clear { color: var(--danger); border-color: rgba(248,113,113,0.4); }
.mt-key.mt-back { color: var(--text-muted); }
.mt-key.mt-eq {
  background: var(--accent); color: #0b0d12; border-color: var(--accent);
  font-size: 1.3rem; font-weight: 700;
}
.mt-key.mt-eq:hover { background: var(--accent); transform: translateY(-1px); }

/* History */
.mt-history {
  background: var(--bg-elev); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 16px; margin-bottom: 16px;
}
.mt-history-head { display: flex; justify-content: space-between; align-items: center; margin-bottom: 8px; }
.mt-section-tag {
  font-family: 'JetBrains Mono', monospace; font-size: 0.72rem; font-weight: 700;
  color: var(--accent); letter-spacing: 0.08em;
}
.mt-history-empty { color: var(--text-muted); font-size: 0.85rem; text-align: center; padding: 12px 0; margin: 0; }
.mt-history-row {
  display: grid; grid-template-columns: 1fr auto auto; gap: 12px; align-items: baseline;
  background: var(--bg); border: 1px solid var(--border); border-radius: 6px;
  padding: 8px 12px; margin-bottom: 4px; cursor: pointer;
  font-family: 'JetBrains Mono', monospace; font-size: 0.85rem;
  transition: border-color 0.15s ease;
}
.mt-history-row:hover { border-color: var(--accent); }
.mt-history-expr { color: var(--text-muted); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.mt-history-eq { color: var(--text-muted); }
.mt-history-result { color: var(--accent); font-weight: 700; text-align: right; }