/* Modern Calculator Styles */
:root {
  --primary-color: #667eea;
  --secondary-color: #764ba2;
  --accent-color: #f093fb;
  --dark-color: #2c3e50;
  --light-color: #ecf0f1;
  --success-color: #2ecc71;
  --warning-color: #f39c12;
  --danger-color: #e74c3c;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
  --shadow-hover: 0 15px 40px rgba(0, 0, 0, 0.3);
}

body {
  background: linear-gradient(
    135deg,
    var(--primary-color) 0%,
    var(--secondary-color) 100%
  );
  min-height: 100vh;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  padding: 20px 0;
}

.calculator-container {
  max-width: 400px;
  margin: 0 auto;
}

.calculator-title {
  color: white;
  text-align: center;
  margin-bottom: 30px;
  font-weight: 300;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
  font-size: 2.5rem;
}

.calculator-card {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-radius: 20px;
  box-shadow: var(--shadow);
  border: none;
  overflow: hidden;
  transition:
    transform 0.3s ease,
    box-shadow 0.3s ease;
}

.calculator-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-hover);
}

.calculator-body {
  padding: 30px;
}

/* Display Styles */
#result {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  border: none;
  border-radius: 15px;
  color: white;
  font-size: 1.8rem;
  font-weight: 500;
  text-align: right;
  padding: 20px;
  margin-bottom: 20px;
  box-shadow: inset 0 2px 10px rgba(0, 0, 0, 0.2);
  min-height: 60px;
}

#result:disabled {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  opacity: 1;
}

#word-result {
  background: linear-gradient(
    135deg,
    var(--accent-color) 0%,
    var(--primary-color) 100%
  );
  border: none;
  border-radius: 12px;
  color: white;
  font-weight: 600;
  text-transform: capitalize;
  padding: 15px 20px;
  margin-bottom: 25px;
  min-height: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  box-shadow: 0 4px 15px rgba(240, 147, 251, 0.3);
  font-size: 1rem;
  line-height: 1.4;
  transition: opacity 0.3s ease;
}

/* Button Styles */
.calc-btn {
  border: none;
  border-radius: 12px;
  font-size: 1.2rem;
  font-weight: 600;
  height: 60px;
  margin: 5px;
  transition: all 0.2s ease;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
  cursor: pointer;
  position: relative;
  overflow: hidden;
}

.calc-btn:before {
  content: "";
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(
    90deg,
    transparent,
    rgba(255, 255, 255, 0.2),
    transparent
  );
  transition: left 0.5s;
}

.calc-btn:hover:before {
  left: 100%;
}

.calc-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.2);
}

.calc-btn:active {
  transform: translateY(0);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
}

/* Number buttons */
.btn-number {
  background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
  color: var(--dark-color);
  border: 1px solid rgba(0, 0, 0, 0.1);
}

.btn-number:hover {
  background: linear-gradient(135deg, #e9ecef 0%, #dee2e6 100%);
  color: var(--dark-color);
}

/* Operator buttons */
.btn-operator {
  background: linear-gradient(
    135deg,
    var(--primary-color) 0%,
    var(--secondary-color) 100%
  );
  color: white;
}

.btn-operator:hover {
  background: linear-gradient(
    135deg,
    var(--secondary-color) 0%,
    var(--primary-color) 100%
  );
  color: white;
}

/* Special buttons */
.btn-clear {
  background: linear-gradient(135deg, var(--danger-color) 0%, #c0392b 100%);
  color: white;
}

.btn-clear:hover {
  background: linear-gradient(135deg, #c0392b 0%, var(--danger-color) 100%);
  color: white;
}

.btn-equals {
  background: linear-gradient(135deg, var(--success-color) 0%, #27ae60 100%);
  color: white;
}

.btn-equals:hover {
  background: linear-gradient(135deg, #27ae60 0%, var(--success-color) 100%);
  color: white;
}

.btn-function {
  background: linear-gradient(135deg, var(--warning-color) 0%, #e67e22 100%);
  color: white;
}

.btn-function:hover {
  background: linear-gradient(135deg, #e67e22 0%, var(--warning-color) 100%);
  color: white;
}

/* Row spacing */
.calc-row {
  margin-bottom: 10px;
}

.calc-row:last-child {
  margin-bottom: 0;
}

/* Responsive design */
@media (max-width: 768px) {
  .calculator-container {
    max-width: 350px;
    margin: 0 15px;
  }

  .calculator-title {
    font-size: 2rem;
  }

  .calc-btn {
    height: 55px;
    font-size: 1.1rem;
  }

  #result {
    font-size: 1.5rem;
    padding: 15px;
  }

  #word-result {
    font-size: 0.9rem;
    padding: 12px 15px;
  }
}

@media (max-width: 480px) {
  .calculator-container {
    max-width: 320px;
  }

  .calc-btn {
    height: 50px;
    font-size: 1rem;
    margin: 3px;
  }

  .calculator-body {
    padding: 20px;
  }
}

/* Animation for button press */
@keyframes buttonPress {
  0% {
    transform: scale(1);
  }
  50% {
    transform: scale(0.95);
  }
  100% {
    transform: scale(1);
  }
}

.calc-btn:active {
  animation: buttonPress 0.1s ease;
}

/* Glow effect for active operations */
.operator-active {
  box-shadow: 0 0 20px var(--accent-color);
}
.math-insight-box {
  margin-top: 10px;
  padding: 10px;
  border-radius: 10px;
  background: rgba(0,0,0,0.05);
  font-size: 0.9rem;
  line-height: 1.5;
}

.dark-mode .math-insight-box {
  background: rgba(255,255,255,0.08);
}
/* ==============================
   📜 CALCULATION HISTORY STYLES
   ============================== */

/* Override opacity:0 set by styles.css on .history-item */
.history-panel .history-item {
  opacity: 1 !important;
  flex-direction: row !important;
  align-items: center !important;
}

.history-panel {
  background: rgba(255, 255, 255, 0.92);
  border-radius: 16px;
  padding: 14px 16px;
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.12);
  backdrop-filter: blur(8px);
  transition: background 0.3s ease;
}

.history-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 700;
  font-size: 0.95rem;
  color: #764ba2;
  margin-bottom: 10px;
  border-bottom: 1px solid rgba(102, 126, 234, 0.2);
  padding-bottom: 8px;
}

.history-clear-btn {
  font-size: 0.75rem;
  padding: 2px 10px;
  border-radius: 20px;
  background: transparent;
  border: 1.5px solid #e74c3c;
  color: #e74c3c;
  cursor: pointer;
  transition: all 0.2s;
}

.history-clear-btn:hover {
  background: #e74c3c;
  color: white;
}

.history-empty-msg {
  font-size: 0.85rem;
  color: #aaa;
  text-align: center;
  margin: 8px 0 4px;
}

.history-list {
  list-style: none;
  padding: 0;
  margin: 0;
  max-height: 220px;
  overflow-y: auto;
}

.history-list::-webkit-scrollbar {
  width: 4px;
}

.history-list::-webkit-scrollbar-thumb {
  background: rgba(102, 126, 234, 0.4);
  border-radius: 4px;
}

.history-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 10px;
  border-radius: 10px;
  font-size: 0.9rem;
  cursor: pointer;
  transition: background 0.18s ease, transform 0.1s ease;
  border-bottom: 1px solid rgba(0,0,0,0.05);
}

.history-item:last-child {
  border-bottom: none;
}

.history-item:hover {
  background: linear-gradient(135deg, rgba(102, 126, 234, 0.12), rgba(118, 75, 162, 0.1));
  transform: translateX(3px);
}

.history-expr {
  color: #555;
  font-size: 0.85rem;
  max-width: 55%;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.history-eq {
  color: #764ba2;
  font-size: 0.92rem;
  text-align: right;
}

/* Flash effect when reusing a history result */
@keyframes reuseFlash {
  0%   { background: linear-gradient(135deg, #f093fb 0%, #667eea 100%); }
  100% { background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); }
}

.reuse-flash {
  animation: reuseFlash 0.4s ease;
}

/* Dark mode support */
.dark-mode .history-panel {
  background: rgba(30, 30, 50, 0.9);
}

.dark-mode .history-header {
  color: #c084fc;
  border-bottom-color: rgba(192, 132, 252, 0.2);
}

.dark-mode .history-item {
  border-bottom-color: rgba(255,255,255,0.06);
}

.dark-mode .history-item:hover {
  background: rgba(192, 132, 252, 0.1);
}

.dark-mode .history-expr {
  color: #bbb;
}

.dark-mode .history-eq {
  color: #c084fc;
}

.dark-mode .history-empty-msg {
  color: #666;
}