/* ── VUNA Calculator — styles.css ── */
:root {
  --primary-color: #0d6efd;
  --card-bg: rgba(255, 255, 255, 0.92);
  --btn-shadow: 0 4px 6px rgba(0,0,0,0.05);
  --btn-hover-shadow: 0 6px 12px rgba(0,0,0,0.12);
}

body {
  background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  min-height: 100vh;
  display: flex;
  align-items: center;
  font-family: 'Segoe UI', Roboto, Arial, sans-serif;
}

/* Theme toggle fixed position */
.theme-toggle-btn {
  position: fixed;
  top: 16px;
  right: 16px;
  z-index: 1000;
}

/* Card */
.calculator-card {
  background: var(--card-bg);
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255,255,255,0.35);
  border-radius: 24px;
  box-shadow: 0 20px 40px rgba(0,0,0,0.10);
  overflow: hidden;
}

/* Display */
.display-container {
  background: #f8f9fa;
  padding: 16px;
  border-radius: 16px;
  margin-bottom: 20px;
  box-shadow: inset 0 2px 4px rgba(0,0,0,0.06);
}

#result {
  font-size: 2rem;
  font-weight: 600;
  text-align: right;
  border: none;
  background: transparent;
  color: #212529;
  box-shadow: none;
  width: 100%;
}

/* Button grid */
.btn-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

.calculator .btn {
  height: 58px;
  border-radius: 14px;
  font-size: 1.1rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  box-shadow: var(--btn-shadow);
  transition: all 0.18s ease;
  cursor: pointer;
}

.calculator .btn:hover  { transform: translateY(-2px); box-shadow: var(--btn-hover-shadow); }
.calculator .btn:active { transform: translateY(0); }

.btn-light    { background: #fff;     color: #495057; }
.btn-light:hover { background: #f1f3f5; color: #212529; }

.btn-operator { background: #e7f1ff; color: var(--primary-color); }
.btn-operator:hover { background: #cfe2ff; }

.btn-action   { background: #fff5f5; color: #fa5252; }
.btn-action:hover { background: #ffe3e3; }

.btn-equals   { background: var(--primary-color); color: #fff; }
.btn-equals:hover { background: #0b5ed7; color: #fff; }

.btn-special  { background: #e7f6ed; color: #198754; font-size: 0.95rem; }
.btn-special:hover { background: #d1f0dd; }

.group-header { font-weight: 700; letter-spacing: 1px; }

/* ── Dark Mode ── */
body.dark-mode { background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%); color: #e0e0e0; }
body.dark-mode .calculator-card { background: rgba(30,30,50,0.95); border-color: rgba(255,255,255,0.08); }
body.dark-mode .display-container { background: #12122a; }
body.dark-mode #result { color: #e0e0e0; }
body.dark-mode .btn-light { background: #2a2a4a; color: #e0e0e0; }
body.dark-mode .btn-light:hover { background: #3a3a5a; }
body.dark-mode .border { border-color: rgba(255,255,255,0.15) !important; }
body.dark-mode .bg-white { background: rgba(255,255,255,0.05) !important; }
body.dark-mode .text-muted { color: #aaa !important; }