body {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

[data-theme="dark"] {
    --bs-body-bg: #121212;
    --bs-body-color: #f8f9fa;
}

[data-theme="dark"] .calculator-card,
[data-theme="dark"] .history-panel {
    background-color: #1e1e1e;
    color: #f8f9fa;
}

[data-theme="dark"] .btn-light {
    background-color: #2d2d2d;
    border-color: #444;
    color: #f8f9fa;
}

[data-theme="dark"] .btn-light:hover {
    background-color: #3d3d3d;
}

[data-theme="dark"] .form-control {
    background-color: #2d2d2d;
    border-color: #444;
    color: #f8f9fa;
}

[data-theme="dark"] .list-group-item {
    background-color: #1e1e1e;
    border-color: #333;
}

.calculator-card {
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

.display-text {
    min-height: 80px;
    font-size: 2.5rem;
    font-weight: 600;
    border-radius: 10px;
    background: linear-gradient(120deg, #f6f8f9 0%, #e5ebee 100%);
    border: none;
    box-shadow: inset 0 2px 5px rgba(0,0,0,0.1);
}

[data-theme="dark"] .display-text {
    background: linear-gradient(120deg, #2a2a2a 0%, #1a1a1a 100%);
    color: #fff;
}

.keypad .btn {
    border-radius: 12px;
    font-weight: 600;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    transition: all 0.2s ease;
}

.keypad .btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 8px rgba(0,0,0,0.15);
}

.keypad .btn:active {
    transform: translateY(0);
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border: none;
}

.btn-success {
    background: linear-gradient(135deg, #11998e 0%, #38ef7d 100%);
    border: none;
}

.btn-danger {
    background: linear-gradient(135deg, #ff416c 0%, #ff4b2b 100%);
    border: none;
}

.history-panel {
    max-height: 500px;
    overflow-y: auto;
    border-radius: 15px;
}

.history-panel .list-group-item {
    border-left: none;
    border-right: none;
    padding: 15px;
}

.history-panel .list-group-item:first-child {
    border-top: none;
}

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

.previous-expression {
    min-height: 25px;
    font-size: 1.2rem;
}

@media (max-width: 992px) {
    .calculator-card {
        margin-bottom: 2rem;
    }
    
    .display-text {
        font-size: 2rem;
    }
}

@media (max-width: 576px) {
    .display-text {
        font-size: 1.5rem;
        min-height: 60px;
    }
    
    .keypad .btn {
        padding: 15px 5px;
        font-size: 1.2rem !important;
    }
}