/* Glass Liquid (Apple) Design System */
:root {
    --glass-bg: rgba(255, 255, 255, 0.1);
    --glass-bg-strong: rgba(255, 255, 255, 0.2);
    --glass-border: rgba(255, 255, 255, 0.3);
    --glass-shadow: 0 8px 32px rgba(0, 0, 0, 0.12);
    --glass-shadow-strong: 0 16px 64px rgba(0, 0, 0, 0.15);
    
    --primary-gradient: linear-gradient(135deg, #007AFF 0%, #5856D6 100%);
    --secondary-gradient: linear-gradient(135deg, #32D74B 0%, #30D158 100%);
    --background-gradient: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
    
    --text-primary: rgba(255, 255, 255, 0.95);
    --text-secondary: rgba(255, 255, 255, 0.7);
    --text-tertiary: rgba(255, 255, 255, 0.5);
    --text-dark: rgba(0, 0, 0, 0.85);
    --text-dark-secondary: rgba(0, 0, 0, 0.6);
    
    --border-radius: 16px;
    --border-radius-large: 24px;
    --border-radius-small: 12px;
    
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 3rem;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'Noto Sans SC', system-ui, sans-serif;
    background: var(--background-gradient);
    min-height: 100vh;
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    position: relative;
    padding-top: 70px; /* 为固定的 nav 留出空间 */
    padding-bottom: 70px; /* 为固定的 footer 留出空间 */
}

body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        radial-gradient(circle at 20% 80%, rgba(120, 119, 198, 0.3) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(255, 119, 198, 0.3) 0%, transparent 50%),
        radial-gradient(circle at 40% 40%, rgba(120, 200, 255, 0.2) 0%, transparent 50%);
    pointer-events: none;
    z-index: -1;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-xl);
}

/* --- 顶部固定导航栏 --- */
.sticky-nav {
    background: var(--glass-bg);
    backdrop-filter: blur(30px);
    -webkit-backdrop-filter: blur(30px);
    border-bottom: 1px solid var(--glass-border);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    height: 70px;
    box-shadow: var(--glass-shadow);
}

.nav-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-xl);
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.nav-logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
    letter-spacing: -0.02em;
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

/* 导航栏分隔线 */
.nav-divider {
    width: 1px;
    height: 24px;
    background: var(--glass-border);
    margin: 0 var(--spacing-sm);
}

/* 导航栏模式切换按钮 */
.mode-container-nav {
    background: var(--primary-gradient);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--border-radius);
    padding: var(--spacing-sm) var(--spacing-md);
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 0.9rem;
    color: white;
    font-weight: 600;
    box-shadow: 0 2px 8px rgba(0, 122, 255, 0.3);
}

.mode-container-nav:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 16px rgba(0, 122, 255, 0.4);
    border-color: rgba(255, 255, 255, 0.3);
}

.mode-container-nav .mode-text {
    font-weight: 700;
    min-width: 16px;
    text-align: center;
    color: white;
}

.mode-container-nav .mode-switch {
    font-size: 1rem;
    color: rgba(255, 255, 255, 0.9);
    transition: all 0.3s ease;
    font-weight: 400;
}

.mode-container-nav:hover .mode-switch {
    color: white;
    transform: scale(1.1);
}

/* --- 示例文本下拉菜单 --- */
.dropdown {
    position: relative;
}

.dropdown-content {
    display: none;
    position: absolute;
    top: calc(100% + 10px);
    right: 0;
    background: rgba(255, 255, 255, 0.4);
    backdrop-filter: blur(30px);
    -webkit-backdrop-filter: blur(30px);
    border: 1px solid var(--glass-border);
    border-radius: var(--border-radius);
    box-shadow: var(--glass-shadow-strong);
    padding: var(--spacing-md);
    min-width: 320px;
    z-index: 1001;
}

.dropdown-content.show {
    display: block;
    animation: fadeInDown 0.3s ease-out;
}

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

.refresh-btn {
    width: 100%;
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-radius: var(--border-radius);
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--text-dark);
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-sm);
}

.refresh-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    border-color: rgba(255, 255, 255, 0.4);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

/* --- 主要内容区域 --- */
.content-area {
    padding-top: var(--spacing-lg);
}

/* Main Converter Section */
.converter-section {
    background: var(--glass-bg);
    backdrop-filter: blur(30px);
    -webkit-backdrop-filter: blur(30px);
    border: 1px solid var(--glass-border);
    border-radius: var(--border-radius-large);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    box-shadow: var(--glass-shadow-strong);
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    align-items: start;
    position: relative;
}

.converter-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.05) 0%, rgba(255, 255, 255, 0.02) 100%);
    border-radius: var(--border-radius-large);
    pointer-events: none;
}

/* Input and Output Sections */
.input-section, .output-section {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.input-header, .output-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.input-header h2, .output-header h2 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    letter-spacing: -0.01em;
}

/* Highlight Toggle */
.highlight-toggle-container {
    display: flex;
    align-items: center;
}

.highlight-toggle {
    display: flex;
    align-items: center;
    cursor: pointer;
    user-select: none;
    gap: var(--spacing-xs);
}

.highlight-toggle input[type="checkbox"] {
    display: none;
}

.toggle-slider-small {
    position: relative;
    width: 40px;
    height: 20px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 20px;
    transition: all 0.3s ease;
    border: 1px solid rgba(255, 255, 255, 0.3);
}

.toggle-slider-small:before {
    content: "";
    position: absolute;
    top: 2px;
    left: 2px;
    width: 14px;
    height: 14px;
    background: white;
    border-radius: 50%;
    transition: all 0.3s ease;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.highlight-toggle input:checked + .toggle-slider-small {
    background: var(--primary-gradient);
    border-color: rgba(0, 122, 255, 0.5);
}

.highlight-toggle input:checked + .toggle-slider-small:before {
    transform: translateX(20px);
}

.toggle-label-small {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
}

/* Highlight Styles */
.highlight-different {
    background: linear-gradient(135deg, #FF6B6B 0%, #FF8E53 100%);
    color: white;
    padding: 2px 6px;
    border-radius: 6px;
    font-weight: 600;
    box-shadow: 0 2px 8px rgba(255, 107, 107, 0.3);
    display: inline-block;
    margin: 0 1px;
    animation: highlightPulse 0.6s ease-out;
}

@keyframes highlightPulse {
    0% { transform: scale(1); box-shadow: 0 2px 8px rgba(255, 107, 107, 0.3); }
    50% { transform: scale(1.05); box-shadow: 0 4px 16px rgba(255, 107, 107, 0.5); }
    100% { transform: scale(1); box-shadow: 0 2px 8px rgba(255, 107, 107, 0.3); }
}

.highlight-character {
    background: linear-gradient(135deg, rgba(255, 193, 7, 0.3) 0%, rgba(255, 235, 59, 0.3) 100%);
    border-bottom: 2px dotted rgba(255, 193, 7, 0.8);
    border-radius: 3px;
    padding: 1px 2px;
    margin: 0 1px;
    display: inline-block;
    transition: all 0.3s ease;
}

.highlight-character:hover {
    background: linear-gradient(135deg, rgba(255, 193, 7, 0.5) 0%, rgba(255, 235, 59, 0.5) 100%);
    transform: translateY(-1px);
    box-shadow: 0 2px 8px rgba(255, 193, 7, 0.3);
}

/* Text Areas */
#input-text {
    width: 100%;
    min-height: 200px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--glass-border);
    border-radius: var(--border-radius);
    padding: var(--spacing-lg);
    color: var(--text-primary);
    font-size: 1rem;
    line-height: 1.6;
    resize: vertical;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    transition: all 0.3s ease;
    font-family: inherit;
}

#input-text::placeholder {
    color: var(--text-tertiary);
}

#input-text:focus {
    outline: none;
    border-color: rgba(0, 122, 255, 0.5);
    background: rgba(255, 255, 255, 0.08);
    box-shadow: 
        0 0 0 3px rgba(0, 122, 255, 0.1),
        var(--glass-shadow);
    transform: translateY(-2px);
}

.output-content {
    width: 100%;
    min-height: 200px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--glass-border);
    border-radius: var(--border-radius);
    padding: var(--spacing-lg);
    color: var(--text-primary);
    font-size: 1rem;
    line-height: 1.6;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    overflow-wrap: break-word;
    word-wrap: break-word;
    white-space: pre-wrap;
}

/* Action Buttons */
.action-btn {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: var(--border-radius);
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--text-primary);
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 0.9rem;
    box-shadow: var(--glass-shadow);
}

.action-btn:hover {
    background: var(--glass-bg-strong);
    transform: translateY(-2px);
    box-shadow: var(--glass-shadow-strong);
}

.action-btn svg {
    width: 16px;
    height: 16px;
    stroke: currentColor;
    fill: none;
    stroke-width: 2;
}

/* Mode Selector */
.control-section {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: var(--spacing-md) 0;
}

.mode-selector {
    display: flex;
    justify-content: center;
}

.mode-container {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: var(--border-radius-large);
    padding: var(--spacing-md) var(--spacing-xl);
    cursor: pointer;
    transition: all 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
    box-shadow: var(--glass-shadow);
}

.mode-container:hover {
    background: var(--glass-bg-strong);
    transform: translateY(-3px) scale(1.02);
    box-shadow: var(--glass-shadow-strong);
}

.mode-text {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    min-width: 24px;
    text-align: center;
    transition: all 0.3s ease;
}

.mode-switch {
    font-size: 1.5rem;
    color: var(--text-secondary);
    transition: all 0.3s ease;
    font-weight: 300;
}

.mode-container:hover .mode-switch {
    color: var(--text-primary);
    transform: scale(1.1);
}

/* Examples Grid */
.examples-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
}

.example-btn {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-radius: var(--border-radius-small);
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--text-dark);
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.875rem;
    text-align: left;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    font-weight: 500;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.example-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    border-color: rgba(255, 255, 255, 0.4);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

/* Toast Messages */
.toast {
    position: fixed;
    top: 90px;
    right: 20px;
    background: var(--glass-bg-strong);
    backdrop-filter: blur(30px);
    -webkit-backdrop-filter: blur(30px);
    border: 1px solid var(--glass-border);
    color: var(--text-primary);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--border-radius);
    box-shadow: var(--glass-shadow-strong);
    transform: translateX(400px);
    opacity: 0;
    transition: all 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    z-index: 10000;
    font-weight: 500;
    max-width: 300px;
}

.toast.show {
    transform: translateX(0);
    opacity: 1;
}

.toast.success {
    border-left: 4px solid #32D74B;
}

.toast.error {
    border-left: 4px solid #FF453A;
}

.toast.info {
    border-left: 4px solid #007AFF;
}

/* Character Count */
.char-count {
    font-size: 0.875rem;
    color: var(--text-secondary);
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--border-radius-small);
    border: 1px solid rgba(255, 255, 255, 0.2);
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

/* --- 底部固定工具栏 --- */
.fixed-footer {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--glass-bg);
    backdrop-filter: blur(30px);
    -webkit-backdrop-filter: blur(30px);
    border-top: 1px solid var(--glass-border);
    height: 70px;
    z-index: 1000;
    box-shadow: 0 -8px 32px rgba(0, 0, 0, 0.12);
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-xl);
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

/* --- 响应式设计 --- */
@media (max-width: 968px) {
    .converter-section {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }
}

@media (max-width: 768px) {
    body {
        padding-top: 60px;
        padding-bottom: 60px;
    }

    .sticky-nav, .fixed-footer {
        height: 60px;
    }

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

    .nav-content, .footer-content {
        padding: 0 var(--spacing-md);
    }

    .nav-actions .action-btn span {
        display: none; /* 在小屏幕上隐藏按钮文字 */
    }
    
    .dropdown .action-btn span {
        display: block; /* 但保留下拉菜单的文字 */
    }
    
    .mode-container-nav {
        padding: var(--spacing-xs) var(--spacing-sm);
        font-size: 0.8rem;
        gap: var(--spacing-xs);
    }
    
    .nav-divider {
        height: 20px;
        margin: 0 var(--spacing-xs);
    }

    .nav-logo {
        font-size: 1.2rem;
    }

    .dropdown-content {
        min-width: 250px;
        right: -20px;
    }

    .converter-section {
        padding: var(--spacing-lg);
    }

    #input-text, .output-content {
        min-height: 150px;
        font-size: 0.9rem;
    }

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

    .char-count {
        font-size: 0.8rem;
    }

    .toggle-label-small {
        font-size: 0.8rem;
    }
}