* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

.calculator-container {
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    max-width: 600px;
    width: 100%;
    overflow: hidden;
}

.header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 30px;
    text-align: center;
}

.header h1 {
    font-size: 2.5em;
    margin-bottom: 10px;
    font-weight: 600;
}

.subtitle {
    font-size: 0.95em;
    opacity: 0.9;
}

.mode-selector {
    display: flex;
    background: #f5f5f5;
    padding: 10px;
    gap: 5px;
    overflow-x: auto;
}

.mode-btn {
    flex: 1;
    padding: 12px 15px;
    background: white;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.9em;
    font-weight: 600;
    color: #666;
    transition: all 0.3s ease;
    white-space: nowrap;
}

.mode-btn:hover {
    background: #f0f0f0;
    border-color: #667eea;
}

.mode-btn.active {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

.calculator-content {
    padding: 30px;
}

.calculator-mode {
    display: none;
}

.calculator-mode.active {
    display: block;
}

/* Basic Calculator Styles */
.display-container {
    margin-bottom: 20px;
}

.display-history {
    min-height: 30px;
    padding: 5px 15px;
    text-align: right;
    color: #999;
    font-size: 0.9em;
}

.display {
    width: 100%;
    padding: 20px;
    font-size: 2em;
    text-align: right;
    border: 2px solid #e0e0e0;
    border-radius: 10px;
    background: #f9f9f9;
    color: #333;
    font-family: 'Courier New', monospace;
    outline: none;
    color-scheme: light;
}

.button-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    margin-top: 20px;
}

.btn {
    padding: 20px;
    font-size: 1.2em;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.2s ease;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

.btn:active {
    transform: translateY(0);
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

.btn.number {
    background: #ffffff;
    color: #333;
    border: 2px solid #e0e0e0;
}

.btn.operator {
    background: #f0f0f0;
    color: #667eea;
    border: 2px solid #667eea;
}

.btn.function {
    background: #764ba2;
    color: white;
}

.btn.equals {
    background: #667eea;
    color: white;
    font-size: 1.5em;
}

/* Equation Solver Styles */
.input-section {
    background: #f9f9f9;
    padding: 25px;
    border-radius: 10px;
    border: 2px solid #e0e0e0;
}

.input-section label {
    display: block;
    margin-bottom: 10px;
    color: #333;
    font-weight: 600;
}

.equation-input {
    width: 100%;
    padding: 15px;
    font-size: 1.1em;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    margin-bottom: 15px;
    font-family: 'Courier New', monospace;
    outline: none;
    transition: border-color 0.3s ease;
    background: #ffffff;
    color: #333;
    color-scheme: light;
}

.equation-input:focus {
    border-color: #667eea;
}

.solve-btn {
    width: 100%;
    padding: 15px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1.1em;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 10px rgba(102, 126, 234, 0.3);
}

.solve-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 15px rgba(102, 126, 234, 0.4);
}

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

.solution-display {
    margin-top: 25px;
    padding: 20px;
    background: #f0f7ff;
    border-left: 4px solid #667eea;
    border-radius: 8px;
    min-height: 50px;
    display: none;
}

.solution-display.show {
    display: block;
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.solution-display h3 {
    color: #667eea;
    margin-bottom: 15px;
    font-size: 1.3em;
}

.solution-display .result {
    font-size: 1.5em;
    color: #333;
    font-weight: 600;
    margin: 15px 0;
    padding: 15px;
    background: white;
    border-radius: 8px;
    font-family: 'Courier New', monospace;
}

.steps {
    margin-top: 20px;
}

.steps h4 {
    color: #764ba2;
    margin-bottom: 10px;
    font-size: 1.1em;
}

.step {
    padding: 12px;
    margin: 8px 0;
    background: white;
    border-radius: 6px;
    border-left: 3px solid #764ba2;
    font-family: 'Courier New', monospace;
    color: #333;
}

/* Quadratic Inputs */
.quadratic-inputs {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 15px;
    margin-bottom: 15px;
}

.input-group {
    display: flex;
    flex-direction: column;
}

.input-group label {
    margin-bottom: 5px;
    font-size: 0.9em;
}

.input-group input {
    padding: 12px;
    font-size: 1.1em;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-family: 'Courier New', monospace;
    outline: none;
    background: #ffffff;
    color: #333;
    color-scheme: light;
}

.input-group input:focus {
    border-color: #667eea;
}

.hint {
    color: #666;
    font-size: 0.9em;
    margin: 10px 0 5px 0;
    font-style: italic;
}

.footer {
    background: #f5f5f5;
    padding: 15px;
    text-align: center;
    color: #666;
    font-size: 0.85em;
    border-top: 1px solid #e0e0e0;
}

.error {
    color: #e74c3c;
    background: #ffeaea;
    border-left-color: #e74c3c;
}

/* Responsive Design */
@media (max-width: 600px) {
    .header h1 {
        font-size: 2em;
    }

    .button-grid {
        gap: 8px;
    }

    .btn {
        padding: 15px;
        font-size: 1em;
    }

    .mode-selector {
        flex-wrap: nowrap;
        overflow-x: auto;
    }

    .quadratic-inputs {
        grid-template-columns: 1fr;
    }
}