/* Button Base */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--border-radius);
    font-weight: var(--font-weight-medium);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-fast);
    border: 2px solid transparent;
    gap: var(--spacing-sm);
    position: relative;
    overflow: hidden;
}

/* Button Sizes */
.btn-sm {
    padding: var(--spacing-xs) var(--spacing-md);
    font-size: var(--font-size-sm);
}

.btn-lg {
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: var(--font-size-lg);
}

.btn-block {
    display: flex;
    width: 100%;
}

/* Button Variants */
.btn-primary {
    background: var(--primary-500);
    color: white;
}

.btn-primary:hover {
    background: var(--primary-600);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-primary:active {
    background: var(--primary-700);
    transform: translateY(0);
    box-shadow: var(--shadow-sm);
}

.btn-outline {
    background: transparent;
    border-color: var(--primary-500);
    color: var(--primary-500);
}

.btn-outline:hover {
    background: var(--primary-500);
    color: white;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-outline:active {
    background: var(--primary-600);
    border-color: var(--primary-600);
    transform: translateY(0);
    box-shadow: var(--shadow-sm);
}

/* Ghost Button */
.btn-ghost {
    background: transparent;
    color: var(--text-primary);
}

.btn-ghost:hover {
    background: var(--bg-secondary);
    transform: translateY(-1px);
}

.btn-ghost:active {
    background: var(--bg-elevated);
    transform: translateY(0);
}

/* Icon Button */
.btn-icon {
    padding: var(--spacing-sm);
    border-radius: var(--border-radius);
}

.btn-icon .icon {
    width: 1.5em;
    height: 1.5em;
}

/* Loading State */
.btn.loading {
    cursor: wait;
    opacity: 0.8;
}

.btn.loading .button-text {
    visibility: hidden;
}

.btn.loading .button-loader {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    display: block;
    width: 1.5em;
    height: 1.5em;
    border: 2px solid currentColor;
    border-radius: 50%;
    border-right-color: transparent;
    animation: button-spin 0.75s linear infinite;
}

@keyframes button-spin {
    from {
        transform: translate(-50%, -50%) rotate(0deg);
    }
    to {
        transform: translate(-50%, -50%) rotate(360deg);
    }
}

/* Disabled State */
.btn:disabled,
.btn[disabled] {
    opacity: 0.5;
    cursor: not-allowed;
    pointer-events: none;
}

/* Button Groups */
.btn-group {
    display: inline-flex;
    gap: var(--spacing-xs);
}

.btn-group .btn {
    border-radius: 0;
}

.btn-group .btn:first-child {
    border-top-left-radius: var(--border-radius);
    border-bottom-left-radius: var(--border-radius);
}

.btn-group .btn:last-child {
    border-top-right-radius: var(--border-radius);
    border-bottom-right-radius: var(--border-radius);
}

/* High Contrast Mode */
@media (forced-colors: active) {
    .btn {
        border: 2px solid ButtonText;
    }
    
    .btn-primary {
        background: Highlight;
        color: HighlightText;
    }
    
    .btn:hover {
        background: Highlight;
        color: HighlightText;
    }
}

/* Responsive Adjustments */
@media (max-width: 768px) {
    .btn-block-mobile {
        width: 100%;
    }
    
    .btn-group {
        flex-direction: column;
    }
    
    .btn-group .btn {
        border-radius: var(--border-radius);
    }
}