/* ===== 公共样式 - 所有页面共享 ===== */

/* CSS变量定义 */
:root {
    --primary: #667eea;
    --primary-light: #764ba2;
    --secondary: #f093fb;
    --accent: #4facfe;
    --success: #00f260;
    --dark: #0f0c29;
    --darker: #0a0a1a;
    --card: rgba(255, 255, 255, 0.05);
    --card-hover: rgba(255, 255, 255, 0.1);
    --text: #ffffff;
    --text-dim: #b8c5d6;
    --border: rgba(255, 255, 255, 0.1);
}

/* 基础重置 */
* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
    font-family: 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
    background: linear-gradient(135deg, var(--darker) 0%, var(--dark) 50%, #1a1a3e 100%);
    color: var(--text);
    line-height: 1.8;
    overflow-x: hidden;
    min-height: 100vh;
}

/* 背景动画 */
.bg-animation {
    position: fixed;
    top: 0; left: 0;
    width: 100%; height: 100%;
    z-index: -1;
    overflow: hidden;
    background: radial-gradient(ellipse at 20% 50%, rgba(102, 126, 234, 0.15) 0%, transparent 50%),
                radial-gradient(ellipse at 80% 20%, rgba(240, 147, 251, 0.1) 0%, transparent 50%),
                radial-gradient(ellipse at 50% 80%, rgba(79, 172, 254, 0.1) 0%, transparent 50%);
    background-size: 200% 200%;
    animation: bgShift 20s ease-in-out infinite alternate;
    will-change: background-position;
}

@keyframes bgShift {
    0% { background-position: 0% 50%; }
    100% { background-position: 100% 50%; }
}

/* 粒子效果 */
.particles {
    position: fixed;
    top: 0; left: 0;
    width: 100%; height: 100%;
    z-index: -1;
    pointer-events: none;
}

.particle {
    position: absolute;
    width: 4px; height: 4px;
    background: radial-gradient(circle, rgba(255,255,255,0.8), rgba(102,126,234,0.3));
    border-radius: 50%;
    animation: particleFloat 15s ease-in-out infinite;
    pointer-events: none;
}

@keyframes particleFloat {
    0%, 100% { transform: translate(0, 0) scale(1); opacity: 0.3; }
    25% { transform: translate(30px, -50px) scale(1.5); opacity: 0.7; }
    50% { transform: translate(-20px, -100px) scale(1); opacity: 0.5; }
    75% { transform: translate(40px, -60px) scale(1.3); opacity: 0.6; }
}

/* 星光效果 */
.stars-container {
    position: fixed;
    top: 0; left: 0;
    width: 100%; height: 100%;
    pointer-events: none;
    z-index: -1;
    overflow: hidden;
}

.star {
    position: absolute;
    width: 3px; height: 3px;
    background: white;
    border-radius: 50%;
    animation: starFloat 12s ease-in-out infinite;
}

.star::before {
    content: '';
    position: absolute;
    top: 50%; left: 50%;
    width: 100%; height: 100%;
    background: inherit;
    border-radius: inherit;
    animation: starPulse 3s ease-in-out infinite;
}

@keyframes starFloat {
    0%, 100% { transform: translateY(0) translateX(0); opacity: 0.4; }
    15% { transform: translateY(-80px) translateX(60px); opacity: 1; }
    35% { transform: translateY(-120px) translateX(-50px); opacity: 0.7; }
    55% { transform: translateY(-180px) translateX(80px); opacity: 0.9; }
    75% { transform: translateY(-140px) translateX(-90px); opacity: 0.6; }
    95% { transform: translateY(-60px) translateX(40px); opacity: 0.8; }
}

@keyframes starPulse {
    0%, 100% { transform: translate(-50%, -50%) scale(1); opacity: 1; }
    50% { transform: translate(-50%, -50%) scale(2.5); opacity: 0; }
}

.star.big { width: 5px; height: 5px; animation-duration: 16s; }
.star.small { width: 2px; height: 2px; animation-duration: 9s; }

/* 导航栏 */
nav {
    position: fixed;
    top: 0; width: 100%;
    background: rgba(15, 12, 41, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    z-index: 1000;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: all 0.3s ease;
}

nav.scrolled {
    padding: 0.75rem 2rem;
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.3);
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--secondary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    display: flex;
    align-items: center;
    gap: .75rem;
    letter-spacing: -0.5px;
}

.logo a {
    color: inherit;
    text-decoration: none;
}

.logo-icon {
    font-size: 2rem;
    animation: pulse 2s ease-in-out infinite;
}

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

.nav-links {
    display: flex;
    gap: 0.5rem;
    list-style: none;
}

.nav-links a {
    color: var(--text-dim);
    text-decoration: none;
    transition: all 0.3s ease;
    font-size: 0.95rem;
    font-weight: 500;
    padding: 0.75rem 1.25rem;
    border-radius: 12px;
    position: relative;
    overflow: hidden;
}

.nav-links a::before {
    content: '';
    position: absolute;
    bottom: 0; left: 50%;
    width: 0; height: 2px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    transition: all 0.3s ease;
    transform: translateX(-50%);
}

.nav-links a:hover, .nav-links a.active {
    color: var(--text);
    background: var(--card);
}

.nav-links a:hover::before, .nav-links a.active::before {
    width: 60%;
}

/* 页面容器 */
.page {
    display: none;
    padding-top: 100px;
    min-height: 100vh;
    animation: fadeInUp 0.5s ease;
}

.page.active { display: block; }

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

/* 进度条 */
.progress-bar {
    position: fixed;
    top: 0; left: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--secondary), var(--accent));
    z-index: 1001;
    transition: width 0.3s ease;
    box-shadow: 0 0 20px var(--primary);
}

/* 跳过链接 */
.skip-link {
    position: absolute;
    top: -100px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--primary);
    color: var(--text);
    padding: 0.75rem 1.5rem;
    border-radius: 0 0 12px 12px;
    z-index: 10000;
    font-weight: 600;
    transition: top 0.3s ease;
    text-decoration: none;
}

.skip-link:focus { top: 0; }

/* 页脚 */
footer {
    text-align: center;
    padding: 4rem 2rem;
    border-top: 1px solid var(--border);
    color: var(--text-dim);
    margin-top: 4rem;
    background: linear-gradient(180deg, transparent, rgba(0, 0, 0, 0.2));
}

footer p:first-child {
    font-size: 1.1rem;
    font-weight: 600;
    background: linear-gradient(135deg, var(--text), var(--primary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

footer p:last-child {
    margin-top: 0.75rem;
    font-size: 0.9rem;
    opacity: 0.7;
}

/* 玻璃拟态效果 */
.card, .chapter-item, .quiz-option, .stat-card, .feature-card, .advanced-card {
    background: rgba(255, 255, 255, 0.05) !important;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

/* 聚焦样式 */
*:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

a:focus-visible, button:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 4px;
    border-radius: 4px;
}

/* 按钮基础样式 */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem 2.5rem;
    border-radius: 14px;
    font-weight: 600;
    font-size: 1.05rem;
    border: none;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    font-family: inherit;
}

.btn--primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
    color: var(--text);
    box-shadow: 0 10px 40px rgba(102, 126, 234, 0.4);
}

.btn--primary:hover {
    transform: translateY(-3px) scale(1.02);
    box-shadow: 0 15px 50px rgba(102, 126, 234, 0.5);
}

.btn--secondary {
    background: var(--card);
    border: 1px solid var(--border);
    color: var(--text);
    box-shadow: none;
}

.btn--secondary:hover {
    background: var(--card-hover);
    border-color: var(--primary);
}

.btn--large {
    padding: 1.2rem 3rem;
    font-size: 1.2rem;
    font-weight: 700;
    border-radius: 50px;
}

.btn--cta {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: var(--text);
    box-shadow: 0 15px 40px rgba(102, 126, 234, 0.4);
}

.btn--cta:hover {
    transform: translateY(-3px);
    box-shadow: 0 20px 50px rgba(102, 126, 234, 0.5);
}

/* 代码块基础样式 */
.code-block, pre.code-block {
    background: #0d0d0d;
    border: 1px solid #1a1a2e;
    border-radius: 12px;
    padding: 0;
    margin: 1.25rem 0;
    font-family: 'Consolas', 'Monaco', 'Fira Code', monospace;
    overflow-x: auto;
    position: relative;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.5), inset 0 1px 0 rgba(255, 255, 255, 0.05);
    display: block;
}

.code-block::before, pre.code-block::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 36px;
    background: linear-gradient(180deg, #1a1a2e 0%, #16213e 100%);
    border-bottom: 1px solid #2a2a4a;
    border-radius: 12px 12px 0 0;
}

.code-block::after, pre.code-block::after {
    content: '';
    position: absolute;
    top: 12px; left: 12px;
    width: 12px; height: 12px;
    background: #ff5f56;
    border-radius: 50%;
    box-shadow: 18px 0 0 #ffbd2e, 36px 0 0 #27ca40;
}

.code-block pre, pre.code-block {
    color: #e2e8f0;
    line-height: 1.7;
    font-size: 0.95rem;
    padding: 48px 1.5rem 1.5rem;
    margin: 0;
    overflow-x: auto;
    white-space: pre;
}

.code-block pre code, pre.code-block code {
    display: block;
}

/* 代码语法高亮 */
.code-keyword { color: #c792ea; font-weight: 600; }
.code-string { color: #c3e88d; }
.code-function { color: #82aaff; }
.code-comment { color: #546e7a; font-style: italic; }
.code-number { color: #f78c6c; }
.code-decorator { color: #ffcb6b; }
.code-builtin { color: #ff79c6; font-weight: 600; }
.code-self { color: #f78c6c; font-style: italic; }
.code-class { color: #ffcb6b; }
.code-operator { color: #89ddff; }
.code-const { color: #82aaff; font-weight: 600; }

/* 代码行号 */
.code-ln {
    color: #4a5568;
    user-select: none;
    pointer-events: none;
    display: inline-block;
    min-width: 2.5em;
    text-align: right;
    margin-right: 1em;
    padding-right: 1em;
    border-right: 1px solid #2a2a4a;
    vertical-align: baseline;
}

/* 代码块复制按钮 */
.code-copy-btn {
    position: absolute;
    top: 8px; right: 12px;
    background: rgba(255,255,255,0.08);
    border: 1px solid rgba(255,255,255,0.12);
    color: #8892b0;
    border-radius: 6px;
    padding: 4px 10px;
    font-size: 11px;
    cursor: pointer;
    transition: all 0.2s;
    z-index: 10;
    font-family: inherit;
}

.code-copy-btn:hover {
    background: rgba(255,255,255,0.15);
    color: #e2e8f0;
}

.code-copy-btn.copied {
    background: rgba(39, 202, 64, 0.2);
    border-color: rgba(39, 202, 64, 0.4);
    color: #27ca40;
}

/* 代码块语言标签 */
.code-lang-tag {
    position: absolute;
    top: 8px; right: 80px;
    background: rgba(66, 102, 245, 0.15);
    border: 1px solid rgba(66, 102, 245, 0.3);
    color: #667eea;
    border-radius: 6px;
    padding: 4px 10px;
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.5px;
    text-transform: uppercase;
}

.code-block:hover, pre.code-block:hover {
    border-color: #2a2a4a;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.5), inset 0 1px 0 rgba(255, 255, 255, 0.05), 0 0 0 1px rgba(102, 126, 234, 0.1);
}

/* 响应式布局 */
@media (max-width: 768px) {
    .nav-links { display: none; }
    .cta-group { flex-direction: column; }
    .cta-btn { width: 100%; justify-content: center; }
}

/* 加载动画 */
.loading {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 200px;
}

.loading::after {
    content: '';
    width: 40px;
    height: 40px;
    border: 3px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}