:root{
  --bg-color: rgba(10,14,20,0.55);
  --card-bg: rgba(255,255,255,0.06);
  --accent: #2196F3;
  --accent-2: #00b894;
  --danger: #ff4757;
  --glass: rgba(255,255,255,0.06);
  --text: #eef2f6;
  --muted: rgba(238,242,246,0.7);
  --glass-border: rgba(255,255,255,0.08);
  --shadow: 0 8px 30px rgba(2,6,23,0.6);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
}

* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; }

/* ------------------------------
   MOBILE-FIRST BASE STYLES
--------------------------------*/

body {
  user-select: none;
  background-image: url('bg2.jpg');
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  color: var(--text);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  padding: 20px;
  padding-top: 100px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  position: relative;
}

header{
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  display:flex;
  align-items:center;
  gap:10px;
  background: linear-gradient(135deg,var(--bg-color), rgba(0,0,0,0.45));
  padding:14px;
  border:1px solid var(--glass-border);
  border-radius:0;
  box-shadow:var(--shadow);
  backdrop-filter: blur(6px) saturate(120%);
}

header h1 {
  margin: 0;
  font-size: 1.15rem;
  letter-spacing: 0.5px;
}

header small { color: var(--muted); }

#volBtn {
  margin-left: auto;
  background: transparent;
  border: 0;
  color: var(--muted);
  cursor: pointer;
  padding: 6px;
  border-radius: 8px;
}
#volBtn:hover {
  background: rgba(255,255,255,0.04);
  color: var(--text);
}

.material-icons { vertical-align: middle; }

/* App container */
.stage{
  width:100%;
  margin:0 auto 40px;
  display:flex;
  justify-content:center;
}

#root{
  width:100%;
  background: linear-gradient(135deg,var(--bg-color), rgba(0,0,0,0.45));
  border-radius:14px;
  padding:16px;
  border:1px solid var(--glass-border);
  box-shadow:var(--shadow);
  backdrop-filter: blur(6px) saturate(120%);
      position: relative;
}

/* Question row */
.top-row{
  display:flex;
  align-items:center;
  gap:10px;
  margin-bottom:12px;
}

#count-down{
  min-width:38px;
  height:38px;
  border-radius:50%;
  display:grid;
  place-items:center;
  background:linear-gradient(180deg,var(--danger), #d63031);
  color:white;
  font-weight:700;
  font-size:0.9rem;
  padding:4px;
  border:2px solid rgba(255,255,255,0.08);
}

.question{
  font-size:1rem;
  padding:10px;
  border-radius:10px;
  background:var(--card-bg);
  border:1px solid var(--glass-border);
}
.question .operand,
.question .operator {
  font-weight:700;
}
.question .operator { margin: 0 8px; }

.answer{
  display:inline-block;
  margin-left:8px;
  padding:6px 10px;
  border-radius:8px;
  background:rgba(0,0,0,0.15);
  font-weight:600;
}

/* Keyboard */
.keyboard{
  display:grid;
  grid-template-columns:repeat(3,1fr);
  gap:10px;
  padding:14px;
  margin-top:14px;
  border-radius:10px;
  background:linear-gradient(180deg, rgba(0,0,0,0.12), rgba(0,0,0,0.08));
}

.key, .enter-btn{
  padding:14px;
  border-radius:8px;
  border:0;
  background:linear-gradient(180deg, rgba(255,255,255,0.06), rgba(255,255,255,0.02));
  color:var(--text);
  font-size:1rem;
  font-weight:600;
  cursor:pointer;
  box-shadow:0 4px 10px rgba(2,6,23,0.35);
}
.key:active{ transform:translateY(1px); }

#kEnter, .enter-btn{
  background:linear-gradient(180deg,var(--accent), #1769aa);
  color:white;
}

#kDel{
  background:linear-gradient(180deg,var(--accent-2), #007f52);
  color:white;
}

/* Micro feedback */
#microfeedback{
  margin-top:12px;
  padding:12px;
  border-radius:8px;
  background:linear-gradient(90deg, rgba(255,255,255,0.04), rgba(255,255,255,0.02));
  border:1px solid rgba(255,255,255,0.04);
  animation:fadeIn .35s ease both;
}

@keyframes fadeIn{
  from{opacity:0; transform:translateY(6px)}
  to{opacity:1; transform:none}
}

/* Footer */
footer{
  margin-top:auto;
  text-align:center;
  color:var(--muted);
  font-size:0.9rem;
  padding:10px 6px;
}

/* ------------------------------
   RESPONSIVE ENHANCEMENTS
--------------------------------*/

/* Medium screens (tablets) */
@media (min-width: 600px){
  body { padding: 40px; padding-top:120px; }
  header h1 { font-size:1.25rem; }
  #root { padding:20px; }
  .question { font-size:1.1rem; }
  #count-down { min-width:42px; height:42px; }
      #microfeedback{ 
            position: absolute;
            top: 0;
        background: darkslategrey;
      }
}

/* Large screens (desktop) */
@media (min-width: 900px){
  body { padding:200px; padding-top:100px; }

  .stage {
    max-width:920px;
    margin-bottom:80px;
  }

  header h1 { font-size:1.35rem; }
  .question { font-size:1.2rem; }
  #count-down { min-width:44px; height:44px; }

  .key, .enter-btn {
    font-size:1.05rem;
  }
}