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

:root {
    --primary-bg: #ffffff;
    --secondary-bg: #f5f5f7;
    --text-primary: #1d1d1f;
    --text-secondary: #86868b;
    --accent: #0071e3;
    --accent-hover: #0077ed;
    --border: #d2d2d7;
    --shadow: rgba(0, 0, 0, 0.1);
    --shadow-hover: rgba(0, 0, 0, 0.15);
    --success: #34c759;
    --spacing-xs: 8px;
    --spacing-sm: 16px;
    --spacing-md: 24px;
    --spacing-lg: 40px;
    --spacing-xl: 64px;
    --border-radius: 12px;
    --border-radius-lg: 18px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    background: var(--primary-bg);
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: var(--spacing-lg) var(--spacing-md);
}

/* Header */
header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    padding-top: var(--spacing-lg);
}

h1 {
    font-size: 48px;
    font-weight: 600;
    letter-spacing: -0.5px;
    margin-bottom: var(--spacing-sm);
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--text-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.subtitle {
    font-size: 20px;
    color: var(--text-secondary);
    font-weight: 400;
}

/* Copy Section */
.copy-section {
    background: var(--secondary-bg);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    box-shadow: 0 2px 8px var(--shadow);
}

.character-display {
    text-align: center;
    margin-bottom: var(--spacing-md);
}

.character-box {
    background: var(--primary-bg);
    border: 2px dashed var(--border);
    border-radius: var(--border-radius);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-sm);
    min-height: 120px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
    position: relative;
}

.character-box:hover {
    border-color: var(--accent);
    box-shadow: 0 4px 12px var(--shadow);
}

.character-box.copy-success {
    border-color: var(--success);
    background: rgba(52, 199, 89, 0.05);
    animation: successPulse 0.6s ease-out;
}

@keyframes successPulse {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.02);
    }
    100% {
        transform: scale(1);
    }
}

#invisibleChar {
    font-size: 24px;
    color: var(--text-secondary);
    user-select: all;
    margin-bottom: var(--spacing-sm);
}

.char-info {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-sm);
    padding-top: var(--spacing-sm);
    border-top: 1px solid var(--border);
    width: 100%;
}

.char-code {
    font-size: 14px;
    font-weight: 600;
    color: var(--accent);
    font-family: 'Monaco', 'Menlo', 'Courier New', monospace;
    letter-spacing: 1px;
}

.char-count {
    font-size: 12px;
    color: var(--text-secondary);
}

.hint {
    font-size: 14px;
    color: var(--text-secondary);
    font-style: italic;
}

.controls {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.character-selector,
.quantity-selector {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

label {
    font-size: 14px;
    font-weight: 500;
    color: var(--text-primary);
}

select,
input[type="number"] {
    padding: 14px 16px;
    border: 1px solid var(--border);
    border-radius: var(--border-radius);
    font-size: 16px;
    font-family: inherit;
    background: var(--primary-bg);
    color: var(--text-primary);
    transition: var(--transition);
    -webkit-appearance: none;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%231d1d1f' d='M6 9L1 4h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 16px center;
    padding-right: 40px;
    min-height: 48px; /* Better touch target for mobile */
    -webkit-tap-highlight-color: rgba(0, 113, 227, 0.1);
    touch-action: manipulation;
}

select:focus,
input[type="number"]:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(0, 113, 227, 0.1);
}

.copy-btn {
    background: var(--accent);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    padding: 16px 32px;
    font-size: 18px;
    font-weight: 500;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    transition: var(--transition);
    box-shadow: 0 4px 12px rgba(0, 113, 227, 0.3);
    min-height: 56px; /* Minimum touch target size for mobile */
    -webkit-tap-highlight-color: rgba(0, 113, 227, 0.2);
    touch-action: manipulation; /* Prevents double-tap zoom on mobile */
}

.copy-btn:hover {
    background: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(0, 113, 227, 0.4);
}

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

.copy-btn.copied {
    background: var(--success);
    box-shadow: 0 4px 12px rgba(52, 199, 89, 0.3);
    animation: buttonSuccess 0.4s ease-out;
}

@keyframes buttonSuccess {
    0% {
        transform: translateY(-2px) scale(1);
    }
    50% {
        transform: translateY(-4px) scale(1.05);
    }
    100% {
        transform: translateY(-2px) scale(1);
    }
}

.btn-icon {
    font-size: 20px;
}

/* Test Section */
.test-section {
    margin-bottom: var(--spacing-lg);
}

h2 {
    font-size: 32px;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    letter-spacing: -0.3px;
}

.section-desc {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    font-size: 16px;
}

.test-box {
    background: var(--secondary-bg);
    border-radius: var(--border-radius);
    padding: var(--spacing-md);
}

#testInput {
    width: 100%;
    padding: 16px;
    border: 1px solid var(--border);
    border-radius: var(--border-radius);
    font-size: 16px;
    font-family: inherit;
    background: var(--primary-bg);
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
    transition: var(--transition);
    min-height: 48px; /* Better touch target for mobile */
    -webkit-tap-highlight-color: rgba(0, 113, 227, 0.1);
    touch-action: manipulation;
}

#testInput:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(0, 113, 227, 0.1);
}

.test-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
}

.test-status {
    font-size: 14px;
    font-weight: 500;
    padding: 4px 8px;
    border-radius: 6px;
    transition: var(--transition);
}

.test-status.success {
    color: var(--success);
    background: rgba(52, 199, 89, 0.1);
}

.test-status.warning {
    color: #ff9500;
    background: rgba(255, 149, 0, 0.1);
}

.test-hint {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm);
    background: rgba(0, 113, 227, 0.05);
    border-radius: var(--border-radius);
    margin-top: var(--spacing-sm);
    font-size: 14px;
    color: var(--text-secondary);
    border-left: 3px solid var(--accent);
}

.hint-icon {
    font-size: 18px;
    flex-shrink: 0;
}

/* Guide Section */
.guide-section {
    margin-bottom: var(--spacing-lg);
}

.guide-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.guide-item {
    background: var(--secondary-bg);
    border-radius: var(--border-radius);
    padding: var(--spacing-md);
    transition: var(--transition);
}

.guide-item:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 16px var(--shadow);
}

.guide-icon {
    font-size: 32px;
    margin-bottom: var(--spacing-sm);
}

.guide-item h3 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.guide-item p {
    color: var(--text-secondary);
    font-size: 14px;
    line-height: 1.5;
}

/* FAQ Section */
.faq-section {
    margin-bottom: var(--spacing-lg);
}

.faq-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.faq-item {
    background: var(--secondary-bg);
    border-radius: var(--border-radius);
    padding: var(--spacing-md);
}

.faq-item h3 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.faq-item p {
    color: var(--text-secondary);
    font-size: 15px;
    line-height: 1.6;
}

/* Footer */
footer {
    text-align: center;
    padding: var(--spacing-lg) 0;
    border-top: 1px solid var(--border);
    margin-top: var(--spacing-xl);
}

footer p {
    color: var(--text-secondary);
    font-size: 14px;
    margin-bottom: var(--spacing-xs);
}

footer a {
    color: var(--accent);
    text-decoration: none;
    transition: var(--transition);
    display: inline-block;
    padding: 4px 8px;
    border-radius: 6px;
}

footer a:hover {
    background: rgba(0, 113, 227, 0.1);
    text-decoration: underline;
}

.footer-links {
    margin: var(--spacing-sm) 0;
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.footer-meta {
    font-size: 12px;
    opacity: 0.7;
}

/* Toast Notification */
.toast {
    position: fixed;
    bottom: var(--spacing-lg);
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: var(--text-primary);
    color: white;
    padding: 18px 28px;
    border-radius: var(--border-radius);
    font-size: 16px;
    font-weight: 500;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.25);
    opacity: 0;
    transition: var(--transition);
    z-index: 1000;
    pointer-events: none;
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    max-width: 90%;
    text-align: center;
}

.toast.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

.toast.pulse {
    animation: toastPulse 0.3s ease-out;
}

@keyframes toastPulse {
    0% {
        transform: translateX(-50%) translateY(0) scale(1);
    }
    50% {
        transform: translateX(-50%) translateY(0) scale(1.05);
    }
    100% {
        transform: translateX(-50%) translateY(0) scale(1);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: var(--spacing-md) var(--spacing-sm);
    }

    h1 {
        font-size: 36px;
    }

    .subtitle {
        font-size: 18px;
    }

    .copy-section {
        padding: var(--spacing-md);
    }

    .guide-grid {
        grid-template-columns: 1fr;
    }

    h2 {
        font-size: 28px;
    }

    .character-box {
        padding: var(--spacing-md);
        min-height: 100px;
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 28px;
    }

    .copy-btn {
        padding: 18px 24px;
        font-size: 18px;
        min-height: 56px; /* Ensure 44px+ touch target on mobile */
        width: 100%; /* Full width on mobile for easier tapping */
    }

    .toast {
        left: var(--spacing-sm);
        right: var(--spacing-sm);
        transform: translateY(100px);
        padding: 16px 20px;
        font-size: 15px;
    }

    .toast.show {
        transform: translateY(0);
    }

    /* Larger touch targets for mobile */
    select,
    input[type="number"] {
        padding: 16px;
        font-size: 16px; /* Prevent zoom on iOS */
        min-height: 48px;
    }

    #testInput {
        padding: 16px;
        font-size: 16px; /* Prevent zoom on iOS */
        min-height: 48px;
    }

    .character-box {
        min-height: 120px;
        padding: var(--spacing-lg);
    }

    /* Better spacing on mobile */
    .controls {
        gap: var(--spacing-md);
    }

    .copy-section {
        padding: var(--spacing-md);
    }

    /* Footer links larger on mobile */
    footer a {
        display: inline-block;
        padding: 8px 12px;
        min-height: 44px;
        line-height: 28px;
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Selection */
::selection {
    background: rgba(0, 113, 227, 0.2);
}