/* ===== Common Styles for Multi-Page Site ===== */
@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@300;400;500;700;900&display=swap');

:root {
    --primary: #ff6b6b;
    --secondary: #4ecdc4;
    --accent: #ffe66d;
    --dark: #2c3e50;
    --light: #f8f9fa;
    --text: #333;
    --text-light: #666;
    --shadow: 0 10px 30px rgba(0,0,0,0.1);
    --shadow-lg: 0 20px 60px rgba(0,0,0,0.15);
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    color: var(--text);
    line-height: 1.8;
    background-color: var(--light);
    overflow-x: hidden;
}

.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

/* ===== Navbar ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: 0 2px 20px rgba(0,0,0,0.1);
    transition: var(--transition);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.nav-logo {
    display: flex;
    align-items: center;
    text-decoration: none;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
}

.logo-icon { margin-right: 10px; font-size: 1.8rem; }

.nav-menu {
    display: flex;
    list-style: none;
    gap: 15px;
}

.nav-link {
    text-decoration: none;
    color: var(--text);
    font-weight: 500;
    font-size: 0.95rem;
    position: relative;
    padding: 5px 0;
    transition: var(--transition);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary);
    transition: var(--transition);
}

.nav-link:hover::after, .nav-link.active::after { width: 100%; }
.nav-link:hover, .nav-link.active { color: var(--primary); }

.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 5px;
}

.nav-toggle span {
    display: block;
    width: 25px;
    height: 3px;
    background-color: var(--text);
    margin: 5px 0;
    transition: var(--transition);
}

/* ===== Page Header ===== */
.page-header {
    padding: 120px 0 60px;
    background: linear-gradient(135deg, #fff5f5 0%, #f0fdfa 100%);
    text-align: center;
}

.page-header h1 {
    font-size: 3rem;
    margin-bottom: 15px;
    line-height: 1.3;
}

.page-header .subtitle {
    font-size: 1.2rem;
    color: var(--text-light);
    max-width: 600px;
    margin: 0 auto;
}

.breadcrumb {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-bottom: 20px;
    font-size: 0.9rem;
    color: var(--text-light);
}

.breadcrumb a {
    color: var(--primary);
    text-decoration: none;
}

.breadcrumb a:hover { text-decoration: underline; }

/* ===== Section Styles ===== */
.section { padding: 80px 0; }
.section-alt { background: white; }
.section-header { text-align: center; margin-bottom: 50px; }

.section-title {
    font-size: 2rem;
    margin-bottom: 15px;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: 2px;
}

.section-subtitle {
    font-size: 1.05rem;
    color: var(--text-light);
    margin-top: 20px;
}

/* ===== Cards ===== */
.card {
    background: white;
    border-radius: 20px;
    padding: 30px;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

/* ===== Buttons ===== */
.btn {
    padding: 12px 28px;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.btn-primary {
    background: var(--primary);
    color: white;
    box-shadow: 0 5px 15px rgba(255, 107, 107, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(255, 107, 107, 0.4);
}

.btn-secondary {
    background: white;
    color: var(--text);
    border: 2px solid #eee;
}

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

/* ===== Grid Layouts ===== */
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 30px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 30px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 25px; }

/* ===== Tip/Info Boxes ===== */
.tip-box {
    background: linear-gradient(135deg, #e8f5e9, #c8e6c9);
    border-left: 4px solid #4caf50;
    padding: 20px;
    border-radius: 0 12px 12px 0;
    margin: 20px 0;
}

.tip-box.warning {
    background: linear-gradient(135deg, #fff3e0, #ffe0b2);
    border-left-color: #ff9800;
}

.tip-box.info {
    background: linear-gradient(135deg, #e3f2fd, #bbdefb);
    border-left-color: #2196f3;
}

.tip-box h4 { margin-bottom: 8px; }

/* ===== Tags ===== */
.tag {
    display: inline-block;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}

.tag-easy { background: #e8f5e9; color: #2e7d32; }
.tag-medium { background: #fff3e0; color: #ef6c00; }
.tag-hard { background: #ffebee; color: #c62828; }

/* ===== Back to Top ===== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 999;
    box-shadow: 0 5px 15px rgba(255, 107, 107, 0.3);
}

.back-to-top.visible { opacity: 1; visibility: visible; }
.back-to-top:hover { transform: translateY(-5px); }

/* ===== Footer ===== */
.footer {
    background: var(--dark);
    color: white;
    padding: 60px 0 25px;
    position: relative;
}

.footer-wave {
    position: absolute;
    top: -1px;
    left: 0;
    width: 100%;
    overflow: hidden;
    line-height: 0;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 40px;
}

.footer-col h4 { font-size: 1.1rem; margin-bottom: 20px; }
.footer-col p { color: #bdc3c7; font-size: 0.95rem; }
.footer-col ul { list-style: none; }
.footer-col ul li { margin-bottom: 10px; }
.footer-col ul li a { color: #bdc3c7; text-decoration: none; transition: var(--transition); font-size: 0.95rem; }
.footer-col ul li a:hover { color: white; }

.footer-bottom {
    text-align: center;
    padding-top: 25px;
    border-top: 1px solid rgba(255,255,255,0.1);
    color: #95a5a6;
    font-size: 0.85rem;
}

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

.animate-in { animation: fadeInUp 0.6s ease forwards; }

/* ===== Responsive ===== */
@media (max-width: 992px) {
    .nav-menu { display: none; position: absolute; top: 70px; left: 0; width: 100%; background: white; flex-direction: column; padding: 20px; box-shadow: 0 10px 30px rgba(0,0,0,0.1); }
    .nav-menu.active { display: flex; }
    .nav-toggle { display: block; }
    .page-header h1 { font-size: 2.2rem; }
    .grid-3 { grid-template-columns: repeat(2, 1fr); }
    .grid-4 { grid-template-columns: repeat(2, 1fr); }
    .footer-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
    .page-header h1 { font-size: 1.8rem; }
    .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
    .footer-grid { grid-template-columns: 1fr; }
    .section { padding: 50px 0; }
}