#tool-wrapper { max-width: 500px; margin: 80px auto 40px; padding: 30px; background: #fff; border-radius: 16px; box-shadow: 0 10px 25px rgba(0,0,0,0.1); }
.dark-mode #tool-wrapper { background: #2c3e50; }
#tool-wrapper h1 { text-align: center; color: #2c3e50; margin-bottom: 30px; }
.dark-mode #tool-wrapper h1 { color: #ecf0f1; }
.calculator { background: #2c3e50; padding: 20px; border-radius: 15px; }
.display input { width: 100%; padding: 15px; font-size: 28px; text-align: right; border: none; border-radius: 10px; background: #34495e; color: white; font-family: monospace; }
.buttons { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; margin-top: 15px; }
.btn { padding: 18px; font-size: 20px; border: none; border-radius: 10px; cursor: pointer; background: #ecf0f1; color: #2c3e50; transition: all 0.2s; }
.btn:hover { background: #d5dbdb; }
.btn.function { background: #95a5a6; color: white; }
.btn.operator { background: #3498db; color: white; }
.btn.operator:hover { background: #2980b9; }
.btn.equals { background: #2ecc71; color: white; }
.btn.equals:hover { background: #27ae60; }
.history { margin-top: 25px; }
.history h3 { color: #2c3e50; margin-bottom: 10px; }
.dark-mode .history h3 { color: #ecf0f1; }
#history-list { max-height: 150px; overflow-y: auto; background: #f8f9fa; padding: 10px; border-radius: 8px; margin-bottom: 10px; }
.dark-mode #history-list { background: #1a252f; }
.history-item { padding: 8px; border-bottom: 1px solid #eee; font-family: monospace; font-size: 14px; }
.dark-mode .history-item { border-color: #34495e; }
#clear-history { padding: 8px 15px; background: #e74c3c; color: white; border: none; border-radius: 5px; cursor: pointer; }