/* Global Resets, Typography, and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Color Palette - Technical Professional */
    --bg-color: #f8fafc;

    /* Very light cool gray */

    /* Clean white for headers */
    --bg-header: rgb(255 255 255 / 90%);

    /* Pure white for cards */
    --bg-card: #fff;

    /* Text Colors - High Contrast */
    --text-main: #334155;

    /* Slate 700 */

    /* Muted text */
    --text-secondary: #64748b;

    /* Slate 500 */

    /* Sharp headings */
    --text-heading: #0f172a;

    /* Slate 900 */

    /* Traffic Hotspot specific (legacy) */
    --traffic-hotspot-text-color: #334155;

    /* Accent Colors - Tech Blue/Indigo */
    --accent: #0284c7;

    /* Sky 600 */

    /* Hover state */
    --accent-hover: #0369a1;

    /* Sky 700 */
    --accent-light: #e0f2fe;

    /* Sky 100 */

    /* Button specific */
    --accent-button: #0284c7;
    --accent-button-hover: #0369a1;

    /* Borders & Shadows */
    --border-color: #cbd5e1;

    /* Slate 300 */
    --border-secondary: #e2e8f0;

    /* Slate 200 */
    --shadow-sm: 0 1px 3px 0 rgb(0 0 0 / 10%), 0 1px 2px -1px rgb(0 0 0 / 10%);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 10%), 0 2px 4px -2px rgb(0 0 0 / 10%);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 10%), 0 4px 6px -4px rgb(0 0 0 / 10%);

    /* Typography */
    --font-main: 'Inter', system-ui, -apple-system, sans-serif;
    --font-heading: 'Noto Sans TC', 'Inter', sans-serif;

    /* Tool wrapper themes (kept for compatibility) */
    --tool-dark-page-bg: #020617;
    --tool-dark-text: #e2e8f0;
    --tool-dark-paragraph: #cbd5f5;
    --tool-dark-frame-bg: #030712;
    --tool-dark-frame-border: #1f2937;
    --tool-light-page-bg: #f7f5f2;
    --tool-light-text: #0f172a;
    --tool-light-paragraph: #4b5563;
    --tool-light-frame-border: #d4d4d8;
    --airplane-alert-bg: var(--tool-dark-frame-bg);
    --airplane-alert-heading: #f8fafc;
    --airplane-alert-paragraph: #94a3b8;

    /* Tool embed base palettes (kept for compatibility) */
    --tool-embed-idle-rgb: 148, 163, 184;
    --tool-embed-monitor-rgb: 59, 130, 246;
    --tool-embed-monitor-border-rgb: 96, 165, 250;
    --tool-embed-monitor-strong-rgb: 37, 99, 235;
    --tool-embed-warning-rgb: 234, 179, 8;
    --tool-embed-warning-soft-rgb: 250, 204, 21;
    --tool-embed-warning-strong-rgb: 217, 119, 6;
    --tool-embed-critical-rgb: 248, 113, 113;
    --tool-embed-critical-strong-rgb: 220, 38, 38;
    --tool-embed-pass-accent-rgb: 252, 165, 165;
    --tool-embed-card-bg-dark: #ffffff0a;
    --tool-embed-card-border-dark: rgb(255 255 255 / 10%);
    --tool-embed-card-shadow-dark: #0f172a40;
    --tool-embed-pass-divider-dark: rgb(255 255 255 / 8%);
    --tool-embed-pass-meta-dark: #ffffffb8;
    --tool-embed-pill-bg: #6366f133;
    --tool-embed-pill-text: #a5b4fc;
    --tool-embed-alert-text-dark: #e2e8f0d9;
    --tool-embed-alert-idle-bg: rgb(var(--tool-embed-idle-rgb) / 14%);
    --tool-embed-alert-idle-border: rgb(var(--tool-embed-idle-rgb) / 28%);
    --tool-embed-alert-monitor-bg: rgb(var(--tool-embed-monitor-rgb) / 16%);
    --tool-embed-alert-monitor-border: rgb(var(--tool-embed-monitor-border-rgb) / 45%);
    --tool-embed-alert-warning-bg: rgb(var(--tool-embed-warning-rgb) / 22%);
    --tool-embed-alert-warning-border: rgb(var(--tool-embed-warning-rgb) / 50%);
    --tool-embed-alert-warning-shadow: rgb(var(--tool-embed-warning-rgb) / 20%);
    --tool-embed-alert-critical-bg: rgb(var(--tool-embed-critical-rgb) / 25%);
    --tool-embed-alert-critical-border: rgb(var(--tool-embed-critical-rgb) / 60%);
    --tool-embed-alert-critical-shadow: rgb(var(--tool-embed-critical-rgb) / 28%);
    --tool-embed-alert-active-outline: rgb(var(--tool-embed-critical-rgb) / 30%);
    --tool-embed-alert-active-shadow: rgb(var(--tool-embed-critical-rgb) / 35%);
    --tool-embed-pass-primary-border: rgb(var(--tool-embed-monitor-border-rgb) / 40%);
    --tool-embed-pass-primary-bg-start: rgb(var(--tool-embed-monitor-rgb) / 16%);
    --tool-embed-pass-primary-bg-end: rgb(var(--tool-embed-monitor-rgb) / 5%);
    --tool-embed-pass-active-border: rgb(var(--tool-embed-critical-rgb) / 60%);
    --tool-embed-pass-active-bg-start: rgb(var(--tool-embed-critical-rgb) / 18%);
    --tool-embed-pass-active-bg-end: rgb(var(--tool-embed-pass-accent-rgb) / 10%);
    --tool-embed-link: #646cff;
    --tool-embed-link-hover: #535bf2;
    --tool-embed-button-bg: #1a1a1a;
    --tool-embed-button-hover-border: #646cff;
    --tool-embed-card-bg-light: #ffffffe6;
    --tool-embed-card-border-light: #0f172a14;
    --tool-embed-card-text-light: #0f172a;
    --tool-embed-pass-meta-light: #0f172ab3;
    --tool-embed-alert-text-light: #0f172ab8;
    --tool-embed-alert-idle-bg-light: rgb(var(--tool-embed-idle-rgb) / 20%);
    --tool-embed-alert-idle-border-light: rgb(var(--tool-embed-idle-rgb) / 45%);
    --tool-embed-alert-monitor-bg-light: rgb(var(--tool-embed-monitor-rgb) / 18%);
    --tool-embed-alert-monitor-border-light: rgb(var(--tool-embed-monitor-strong-rgb) / 45%);
    --tool-embed-alert-warning-bg-light: rgb(var(--tool-embed-warning-soft-rgb) / 28%);
    --tool-embed-alert-warning-border-light: rgb(var(--tool-embed-warning-strong-rgb) / 50%);
    --tool-embed-alert-warning-shadow-light: rgb(var(--tool-embed-warning-strong-rgb) / 20%);
    --tool-embed-alert-critical-bg-light: rgb(var(--tool-embed-critical-rgb) / 28%);
    --tool-embed-alert-critical-border-light: rgb(var(--tool-embed-critical-strong-rgb) / 55%);
    --tool-embed-alert-critical-shadow-light: rgb(var(--tool-embed-critical-strong-rgb) / 28%);
    --tool-embed-alert-active-outline-light: rgb(var(--tool-embed-critical-strong-rgb) / 25%);
    --tool-embed-alert-active-shadow-light: rgb(var(--tool-embed-critical-strong-rgb) / 32%);
    --tool-embed-button-bg-light: #f9f9f9;
    --tool-embed-link-hover-light: #747bff;

    /* Hero Gradients */
    --hero-bg-start: #f8fafc;
    --hero-bg-end: #e2e8f0;
    --hero-overlay-start: rgb(2 132 199 / 3%);
    --hero-overlay-end: rgb(255 255 255 / 0%);
}

/* Theme Toggle Button */
.theme-btn {
    background: none;
    border: 1px solid var(--border-color);
    border-radius: 50%;
    cursor: pointer;
    font-size: 1.2rem;
    padding: 0.5rem;
    line-height: 1;
    color: var(--text-main);
    transition: all 0.2s ease;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-btn:hover {
    background-color: var(--border-secondary);
    transform: rotate(15deg);
}

/* Dark Theme Mixin */
:root[data-theme="dark"] {
    /* Dark Mode Palette - Deep Space/Slate */
    --bg-color: #0f172a;
    --bg-header: rgb(15 23 42 / 90%);
    --bg-card: #1e293b;
    --text-main: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-heading: #f8fafc;
    --traffic-hotspot-text-color: #f1f5f9;
    --border-color: #334155;
    --border-secondary: #475569;
    --shadow-sm: 0 1px 3px 0 rgb(0 0 0 / 30%), 0 1px 2px -1px rgb(0 0 0 / 20%);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 30%), 0 2px 4px -2px rgb(0 0 0 / 20%);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 30%), 0 4px 6px -4px rgb(0 0 0 / 20%);
    --hero-bg-start: #0f172a;
    --hero-bg-end: #1e293b;
    --hero-overlay-start: rgb(56 189 248 / 5%);
    --hero-overlay-end: rgb(15 23 42 / 0%);
}





/* Layout & Global Styles */
body {
    font-family: var(--font-main);
    line-height: 1.7;
    color: var(--text-main);
    background-color: var(--bg-color);
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3,
h4,
h5,
h6 {
    font-family: var(--font-heading);
    color: var(--text-heading);
    font-weight: 700;
    line-height: 1.3;
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: color 0.2s ease;
    font-weight: 500;
}

a:hover {
    color: var(--accent-hover);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
    max-width: 1200px;
    margin: 0 auto;
}

.menu-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text-main);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
}

.logo {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--text-heading);
    letter-spacing: -0.02em;
}

/* Hidden but accessible headings */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    margin: -1px;
    padding: 0;
    overflow: hidden;
    clip: rect(0 0 0 0);
    white-space: nowrap;
    border: 0;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2.5rem;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    transition: color 0.2s ease;
}

.nav-links a:hover {
    color: var(--accent);
}

/* Hero Section */
.hero {
    text-align: center;
    padding: 6rem 1rem;
    background: linear-gradient(135deg, var(--hero-bg-start) 0%, var(--hero-bg-end) 100%);
    border-radius: 24px;
    margin-bottom: 4rem;
    border: 1px solid var(--border-color);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, var(--hero-overlay-start) 0%, var(--hero-overlay-end) 70%);
    pointer-events: none;
}

.hero h1 {
    font-size: 3rem;
    color: var(--text-heading);
    margin-bottom: 1.5rem;
    letter-spacing: -0.03em;
}

.hero p {
    font-size: 1.25rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* Section Styling */
section {
    margin-bottom: 5rem;
    animation: fade-in 0.8s ease-out forwards;
    opacity: 0;
}

section:nth-child(1) {
    animation-delay: 0.1s;
}

section:nth-child(2) {
    animation-delay: 0.2s;
}

section:nth-child(3) {
    animation-delay: 0.3s;
}

@keyframes fade-in {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

section h2 {
    font-size: 1.75rem;
    margin-bottom: 2rem;
    position: relative;
    padding-left: 1rem;
    border-left: 4px solid var(--accent);
}

/* Topics Grid */
.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.topic-card {
    display: flex;
    flex-direction: column;
    background: var(--bg-card);
    padding: 2rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);

    --card-accent-color: var(--accent);

    border-left: 4px solid var(--card-accent-color);
    box-shadow: var(--shadow-sm);
    transition: all 0.2s ease-in-out;
    text-decoration: none;
    color: inherit;
    cursor: pointer;
    height: 100%;
}

.topic-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--accent);
    background-color: var(--bg-color);
}

.topic-card-amber {
    --card-accent-color: #f59e0b;

    /* Override default accent */
}

.topic-card-emerald {
    --card-accent-color: #10b981;
}

.topic-card-slate {
    --card-accent-color: #64748b;
}

.topic-card h2,
.topic-card h3 {
    font-size: 1.25rem;
    color: var(--text-heading);
    margin-bottom: 0.75rem;
    border: none;
    padding: 0;
}

.topic-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
}

/* Coming-soon idea cards */
.topic-card-soon {
    cursor: default;
    border-left-style: dashed;
}

.topic-card-soon:hover {
    transform: none;
    box-shadow: var(--shadow-sm);
    border-color: var(--border-color);
    border-left-color: var(--card-accent-color);
    background-color: var(--bg-card);
}

.topic-card-status {
    margin-top: auto;
    padding-top: 1rem;
    font-size: 0.8rem;
    font-weight: 600;
    letter-spacing: 0.03em;
    color: var(--text-secondary);
}

/* Priority "build first" coming-soon cards */
.topic-card-priority {
    border-left-style: solid;
    border-left-color: var(--accent);
}

.topic-card-priority:hover {
    border-left-color: var(--accent);
}

.topic-card-priority-badge {
    display: inline-block;
    align-self: flex-start;
    margin-bottom: 0.75rem;
    padding: 0.2rem 0.65rem;
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.03em;
    color: #fff;
    background-color: var(--accent);
    border-radius: 999px;
}

.coming-soon-section h2 {
    margin-bottom: 0.5rem;
}

.coming-soon-section > p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

/* Knowledge Highlight */
.knowledge-highlight {
    background: var(--bg-card);
    padding: 3rem;
    border-radius: 16px;
    text-align: center;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.knowledge-highlight .topic-card {
    max-width: 400px;
    margin: 0 auto;
    box-shadow: none;
    border: 1px solid var(--border-secondary);
}

/* Chart container */
.chart-container {
    position: relative;
    height: 400px;
    width: 100%;
    max-width: 800px;
    margin: auto;
}

/* Article Page Styling */
.article {
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem;
}

.article h1 {
    font-size: 2.5rem;
    margin-bottom: 2rem;
    color: var(--text-heading);
}

.article h2 {
    font-size: 1.75rem;
    margin: 2.5rem 0 1.5rem;
    color: var(--text-heading);
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.5rem;
}

.article p {
    margin: 1.25rem 0;
    color: var(--text-secondary);
    font-size: 1.05rem;
}

/* Quiz form */
.quiz-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.quiz-question {
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1.25rem;
    background: var(--bg-card);
    box-shadow: var(--shadow-sm);
}

.quiz-question legend {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
}

.quiz-option {
    display: flex;
    align-items: flex-start;
    gap: 0.85rem;
    padding: 1rem 1.25rem;
    border: 1px solid var(--border-secondary);
    border-radius: 12px;
    background-color: #f9f7f4;
    cursor: pointer;
    transition: border-color 0.2s ease, box-shadow 0.2s ease, background-color 0.2s ease;
}

.quiz-option+.quiz-option {
    margin-top: 0.75rem;
}

.quiz-option:hover,
.quiz-option:focus-within {
    border-color: var(--accent);
    background-color: #fff7f1;
    box-shadow: 0 6px 18px rgb(194 121 77 / 12%);
}

.quiz-option input[type="radio"] {
    width: 1.25rem;
    height: 1.25rem;
    margin-top: 0.2rem;
    flex-shrink: 0;
    accent-color: var(--accent);
}

.option-text {
    font-size: 1rem;
    color: var(--text-main);
    line-height: 1.6;
}

.quiz-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
}

.quiz-actions .button {
    flex: 1 1 240px;
    padding: 0.9rem 1.5rem;
    font-size: 1rem;
}

.quiz-actions .secondary {
    background: transparent;
}

@media (width <= 600px) {
    .quiz-question {
        padding: 1rem;
    }

    .quiz-option {
        padding: 0.9rem 1rem;
    }

    .quiz-option input[type="radio"] {
        margin-top: 0.15rem;
    }
}

/* Tech news cards */
.cards img {
    width: 100%;
    aspect-ratio: 16 / 9;
    object-fit: cover;
    border-radius: 12px;
}

.pre-line-text {
    white-space: pre-line;
}

/* Footer */
footer {
    text-align: center;
    padding: 3rem 0;
    margin-top: 6rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Responsive Design */
@media (width <=768px) {
    .menu-toggle {
        display: block;
    }

    nav {
        flex-direction: column;
        align-items: flex-start;
        padding: 1rem;
    }

    .nav-links {
        display: none;
        flex-direction: column;
        width: 100%;
        gap: 1rem;
        margin-top: 1.5rem;
        padding-top: 1rem;
        border-top: 1px solid var(--border-color);
    }

    nav.nav-open .nav-links {
        display: flex;
    }

    .hero {
        padding: 4rem 1rem;
    }

    .hero h1 {
        font-size: 2.25rem;
    }

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

    .article {
        padding: 1rem 0;
    }
}

@media (width <=600px) {
    body {
        padding: 0 16px;
    }
}

/* Utilities */
.image-gallery {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    justify-content: center;
    margin: 2rem 0;
}

.image-gallery img {
    max-width: 100%;
    height: auto;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.rates-table {
    width: 100%;
    max-width: 500px;
    margin: 2rem auto;
    border-collapse: separate;
    border-spacing: 0;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    overflow: hidden;
}

.rates-table th,
.rates-table td {
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.rates-table th {
    background-color: #f9f7f4;
    font-weight: 600;
    text-align: left;
}

.rates-table td:last-child {
    text-align: right;
    font-variant-numeric: tabular-nums;
    font-weight: 500;
}

.rates-table tr:last-child td {
    border-bottom: none;
}

/* Image opacity in dark mode (Moved to end for specificity) */
:root[data-theme="dark"] img {
    opacity: 0.9;
    transition: opacity 0.3s ease;
}

:root[data-theme="dark"] img:hover {
    opacity: 1;
}