/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #667eea;
    --primary-dark: #5568d3;
    --secondary-color: #764ba2;
    --danger-color: #f56565;
    --danger-dark: #e53e3e;
    --success-color: #48bb78;
    --success-dark: #38a169;
    --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --text-dark: #2d3748;
    --text-light: #718096;
    --white: #ffffff;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1), 0 2px 4px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 20px rgba(0, 0, 0, 0.15), 0 3px 6px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.2), 0 5px 10px rgba(0, 0, 0, 0.12);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--bg-gradient);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    color: var(--text-dark);
}

/* Container */
.container {
    background: var(--white);
    border-radius: 24px;
    box-shadow: var(--shadow-xl);
    max-width: 500px;
    width: 100%;
    padding: 40px 30px;
    animation: fadeInUp 0.6s ease-out;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Header */
header {
    text-align: center;
    margin-bottom: 40px;
}

h1 {
    font-size: 2rem;
    font-weight: 700;
    background: var(--bg-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 8px;
}

.subtitle {
    color: var(--text-light);
    font-size: 0.95rem;
}

/* Counter Display */
.counter-display {
    background: var(--bg-gradient);
    border-radius: 20px;
    padding: 50px 30px;
    text-align: center;
    margin-bottom: 30px;
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
}

.counter-display::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at center, rgba(255, 255, 255, 0.1) 0%, transparent 70%);
    pointer-events: none;
}

#counter-value {
    font-size: 5rem;
    font-weight: 700;
    color: var(--white);
    display: block;
    position: relative;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
    transition: transform 0.3s ease;
}

#counter-value.pulse {
    animation: pulse 0.3s ease;
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.1);
    }
}

/* Button Group */
.button-group {
    display: flex;
    gap: 12px;
    margin-bottom: 30px;
    flex-wrap: wrap;
}

.btn {
    flex: 1;
    min-width: 120px;
    padding: 16px 20px;
    border: none;
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.3);
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
}

.btn:active::before {
    width: 300px;
    height: 300px;
}

.btn svg {
    width: 20px;
    height: 20px;
}

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

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

.btn-increment {
    background: var(--success-color);
    color: var(--white);
}

.btn-increment:hover {
    background: var(--success-dark);
}

.btn-decrement {
    background: var(--danger-color);
    color: var(--white);
}

.btn-decrement:hover {
    background: var(--danger-dark);
}

.btn-reset {
    background: var(--text-light);
    color: var(--white);
}

.btn-reset:hover {
    background: var(--text-dark);
}

/* Stats */
.stats {
    background: #f7fafc;
    border-radius: 12px;
    padding: 20px;
    margin-bottom: 20px;
}

.stat-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.stat-label {
    font-size: 0.9rem;
    color: var(--text-light);
    font-weight: 500;
}

.stat-value {
    font-size: 0.9rem;
    color: var(--text-dark);
    font-weight: 600;
}

/* Footer */
footer {
    text-align: center;
}

footer p {
    font-size: 0.85rem;
    color: var(--text-light);
}

/* Responsive Design */
@media (max-width: 600px) {
    .container {
        padding: 30px 20px;
    }
    
    h1 {
        font-size: 1.75rem;
    }
    
    .subtitle {
        font-size: 0.875rem;
    }
    
    .counter-display {
        padding: 40px 20px;
    }
    
    #counter-value {
        font-size: 4rem;
    }
    
    .button-group {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
        min-width: auto;
    }
}

@media (max-width: 400px) {
    h1 {
        font-size: 1.5rem;
    }
    
    #counter-value {
        font-size: 3.5rem;
    }
    
    .btn {
        padding: 14px 18px;
        font-size: 0.95rem;
    }
}

/* Error notification animations */
@keyframes slideIn {
    from {
        transform: translateX(400px);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

@keyframes slideOut {
    from {
        transform: translateX(0);
        opacity: 1;
    }
    to {
        transform: translateX(400px);
        opacity: 0;
    }
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    :root {
        --text-dark: #e2e8f0;
        --text-light: #a0aec0;
    }
}