/* ============================================
   PREMIUM BUTTON SYSTEM - Kids Learning Platform
   ============================================ */

/* Base Button Styles */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    padding: 0.875rem 1.75rem;
    font-weight: 600;
    font-size: 1rem;
    line-height: 1.5;
    text-align: center;
    text-decoration: none;
    border: 2px solid transparent;
    border-radius: var(--border-radius-btn);
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    user-select: none;
    white-space: nowrap;
    position: relative;
    overflow: hidden;
    min-height: var(--touch-target-min);
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    pointer-events: none;
}

/* Button Sizes */
.btn-sm {
    padding: 0.625rem 1.25rem;
    font-size: 0.875rem;
    min-height: 40px;
}

.btn-lg {
    padding: 1.125rem 2.25rem;
    font-size: 1.125rem;
    min-height: 56px;
}

.btn-xl {
    padding: 1.25rem 2.5rem;
    font-size: 1.25rem;
    min-height: 64px;
}

/* Icon-only Buttons */
.btn-icon {
    padding: 0;
    width: var(--touch-target-min);
    height: var(--touch-target-min);
}

.btn-icon.btn-sm {
    width: 40px;
    height: 40px;
}

/* Primary Button (Gradient, Premium Feel) */
.btn-primary {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
    color: white;
    box-shadow: var(--shadow-brand);
}

.btn-primary:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: var(--shadow-brand-lg);
    background: linear-gradient(135deg, var(--color-primary-dark) 0%, var(--color-primary) 100%);
}

.btn-primary:active:not(:disabled) {
    transform: translateY(0);
    box-shadow: var(--shadow-sm);
}

/* Magical Gradient Variant */
.btn-magical {
    background: linear-gradient(135deg, #a78bfa 0%, #60a5fa 50%, #f472b6 100%);
    background-size: 200% 200%;
    color: white;
    box-shadow: var(--shadow-lg);
    animation: gradient-shift 3s ease infinite;
}

@keyframes gradient-shift {
    0%, 100% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
}

.btn-magical:hover:not(:disabled) {
    transform: translateY(-2px) scale(1.02);
    box-shadow: var(--shadow-xl);
}

/* Secondary Button */
.btn-secondary {
    background: white;
    color: var(--color-primary);
    border-color: var(--color-primary);
    box-shadow: var(--shadow-sm);
}

.btn-secondary:hover:not(:disabled) {
    background: rgba(107, 151, 196, 0.05);
    border-color: var(--color-primary-dark);
    box-shadow: var(--shadow-md);
    transform: translateY(-1px);
}

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

.btn-ghost:hover:not(:disabled) {
    background: rgba(107, 151, 196, 0.1);
}

/* Success Button */
.btn-success {
    background: linear-gradient(135deg, var(--color-success) 0%, var(--color-success-light) 100%);
    color: white;
    box-shadow: var(--shadow-success);
}

.btn-success:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(16, 185, 129, 0.3);
}

/* Destructive Button */
.btn-destructive {
    background: linear-gradient(135deg, var(--color-error) 0%, var(--color-error-light) 100%);
    color: white;
    box-shadow: var(--shadow-error);
}

.btn-destructive:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(239, 68, 68, 0.3);
}

/* Warning Button */
.btn-warning {
    background: linear-gradient(135deg, var(--color-warning) 0%, var(--color-warning-light) 100%);
    color: white;
    box-shadow: 0 4px 16px rgba(245, 158, 11, 0.2);
}

.btn-warning:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(245, 158, 11, 0.3);
}

/* Button with Shine Effect */
.btn-shine::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(
        90deg,
        transparent 0%,
        rgba(255, 255, 255, 0.3) 50%,
        transparent 100%
    );
    transition: left 0.5s ease;
}

.btn-shine:hover::before {
    left: 100%;
}

/* Ripple Effect (triggered by JS) */
.btn-ripple {
    position: relative;
    overflow: hidden;
}

.ripple {
    position: absolute;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.6);
    transform: scale(0);
    animation: ripple-animation 0.6s ease-out;
    pointer-events: none;
}

@keyframes ripple-animation {
    to {
        transform: scale(4);
        opacity: 0;
    }
}

/* Loading State */
.btn-loading {
    position: relative;
    color: transparent !important;
    pointer-events: none;
}

.btn-loading::after {
    content: '';
    position: absolute;
    width: 1.25rem;
    height: 1.25rem;
    top: 50%;
    left: 50%;
    margin-left: -0.625rem;
    margin-top: -0.625rem;
    border: 2px solid currentColor;
    border-radius: 50%;
    border-top-color: transparent;
    animation: btn-spinner 0.6s linear infinite;
    color: white;
}

.btn-secondary.btn-loading::after,
.btn-ghost.btn-loading::after {
    color: var(--color-primary);
}

@keyframes btn-spinner {
    to {
        transform: rotate(360deg);
    }
}

/* Button Groups */
.btn-group {
    display: inline-flex;
    border-radius: var(--border-radius-btn);
    box-shadow: var(--shadow-sm);
}

.btn-group .btn {
    border-radius: 0;
    margin-left: -2px;
}

.btn-group .btn:first-child {
    border-top-right-radius: var(--border-radius-btn);
    border-bottom-right-radius: var(--border-radius-btn);
    margin-left: 0;
}

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

.btn-group .btn:only-child {
    border-radius: var(--border-radius-btn);
}

/* Full Width Button */
.btn-block {
    display: flex;
    width: 100%;
}

/* Elevated Button (more shadow) */
.btn-elevated {
    box-shadow: var(--shadow-lg);
}

.btn-elevated:hover:not(:disabled) {
    box-shadow: var(--shadow-xl);
}

/* Outline Buttons */
.btn-outline-primary {
    background: transparent;
    color: var(--color-primary);
    border-color: var(--color-primary);
}

.btn-outline-primary:hover:not(:disabled) {
    background: var(--color-primary);
    color: white;
}

/* Social Login Buttons */
.btn-google {
    background: white;
    color: #5f6368;
    border: 1px solid #dadce0;
    box-shadow: var(--shadow-sm);
}

.btn-google:hover:not(:disabled) {
    box-shadow: var(--shadow-md);
    background: #f8f9fa;
}

.btn-apple {
    background: #000;
    color: white;
}

.btn-apple:hover:not(:disabled) {
    background: #1a1a1a;
}

/* Responsive Adjustments */
@media (hover: none) {
    /* Touch devices - remove hover transforms, use active state */
    .btn:active:not(:disabled) {
        transform: scale(0.97);
    }
    
    .btn-primary:active:not(:disabled),
    .btn-success:active:not(:disabled),
    .btn-destructive:active:not(:disabled),
    .btn-warning:active:not(:disabled) {
        transform: scale(0.97);
        box-shadow: var(--shadow-sm);
    }
}

@media (max-width: 640px) {
    .btn {
        font-size: 0.9375rem;
    }
    
    .btn-lg {
        padding: 1rem 2rem;
    }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
    .btn,
    .btn::before,
    .ripple {
        animation: none;
        transition: none;
    }
    
    .btn:hover:not(:disabled) {
        transform: none;
    }
}