:root {
    --bg-color: #0d1117;
    --card-bg: #161b22;
    --border-color: #30363d;
    --text-primary: #e6edf3;
    --text-secondary: #8b949e;
    --accent-color: #2f81f7;
    --accent-hover: #388bfd;
    --success-color: #238636;
    --success-hover: #2ea043;
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP", Roboto, Helvetica, Arial, sans-serif;
    --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: var(--font-sans);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.site-header {
    background-color: var(--card-bg);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}
.header-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0.8rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}
.logo a {
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 700;
    font-size: 1.25rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.logo-icon { color: #f1e05a; font-size: 1.4rem; }
.badge {
    background: #1f6feb;
    color: white;
    font-size: 0.75rem;
    padding: 0.15rem 0.45rem;
    border-radius: 4px;
    margin-left: 0.3rem;
}
.main-nav {
    display: flex;
    gap: 1.2rem;
    flex-wrap: wrap;
}
.nav-item {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.95rem;
    transition: color 0.2s;
}
.nav-item:hover, .nav-item.active {
    color: var(--accent-color);
    font-weight: 500;
}
.header-badge {
    font-size: 0.8rem;
    color: #3fb950;
    background: rgba(63, 185, 80, 0.1);
    border: 1px solid rgba(63, 185, 80, 0.3);
    padding: 0.2rem 0.6rem;
    border-radius: 20px;
    display: flex;
    align-items: center;
    gap: 0.4rem;
}
.status-indicator {
    width: 8px;
    height: 8px;
    background: #3fb950;
    border-radius: 50%;
    display: inline-block;
}

main.main-content {
    flex: 1;
    max-width: 1100px;
    width: 100%;
    margin: 2rem auto;
    padding: 0 1.5rem;
}

.hero-section {
    text-align: center;
    padding: 3rem 1rem;
    background: linear-gradient(180deg, rgba(31, 111, 235, 0.08) 0%, transparent 100%);
    border-radius: 12px;
    border: 1px solid var(--border-color);
    margin-bottom: 2.5rem;
}
.hero-title {
    font-size: 2.2rem;
    margin-bottom: 0.8rem;
    font-weight: 800;
    letter-spacing: -0.5px;
}
.hero-desc {
    color: var(--text-secondary);
    font-size: 1.1rem;
    max-width: 700px;
    margin: 0 auto;
}

.grid-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin-bottom: 3rem;
}
.card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    text-decoration: none;
    color: inherit;
    transition: transform 0.2s, border-color 0.2s;
    display: flex;
    flex-direction: column;
}
.card:hover {
    transform: translateY(-3px);
    border-color: var(--accent-color);
}
.card-icon {
    font-size: 2rem;
    margin-bottom: 0.8rem;
}
.card-title {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}
.card-desc {
    color: var(--text-secondary);
    font-size: 0.9rem;
    flex: 1;
}
.card-tag {
    margin-top: 1rem;
    font-size: 0.75rem;
    color: var(--accent-color);
    align-self: flex-start;
    background: rgba(47, 129, 247, 0.1);
    padding: 0.1rem 0.5rem;
    border-radius: 4px;
}

.tool-container {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 2rem;
    margin-bottom: 2rem;
}
.tool-header {
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1rem;
    margin-bottom: 1.5rem;
}
.tool-header h1 { font-size: 1.8rem; margin-bottom: 0.4rem; }
.tool-header p { color: var(--text-secondary); font-size: 0.95rem; }

.form-group { margin-bottom: 1.2rem; }
label { display: block; margin-bottom: 0.4rem; font-size: 0.9rem; font-weight: 600; }
textarea, input[type="text"], input[type="number"], select {
    width: 100%;
    background: #0d1117;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    padding: 0.75rem;
    font-family: var(--font-mono);
    font-size: 0.9rem;
    resize: vertical;
}
textarea:focus, input:focus, select:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(47, 129, 247, 0.2);
}

.btn-group {
    display: flex;
    gap: 0.8rem;
    flex-wrap: wrap;
    margin: 1rem 0;
}
button, .btn {
    background: #21262d;
    color: #c9d1d9;
    border: 1px solid var(--border-color);
    padding: 0.5rem 1rem;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 500;
    font-size: 0.9rem;
    transition: all 0.2s;
}
button:hover, .btn:hover {
    background: #30363d;
    border-color: #8b949e;
}
button.btn-primary {
    background: var(--success-color);
    color: white;
    border-color: rgba(240, 246, 252, 0.1);
}
button.btn-primary:hover {
    background: var(--success-hover);
}
button.btn-accent {
    background: var(--accent-color);
    color: white;
}
button.btn-accent:hover {
    background: var(--accent-hover);
}

.result-box {
    background: #090d13;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 1rem;
    font-family: var(--font-mono);
    font-size: 0.9rem;
    white-space: pre-wrap;
    word-break: break-all;
    min-height: 80px;
    position: relative;
}

.toast {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background: #238636;
    color: white;
    padding: 0.6rem 1.2rem;
    border-radius: 6px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.4);
    opacity: 0;
    transition: opacity 0.3s;
    pointer-events: none;
    z-index: 1000;
}
.toast.show { opacity: 1; }

.site-footer {
    background-color: var(--card-bg);
    border-top: 1px solid var(--border-color);
    margin-top: auto;
    padding: 3rem 1.5rem 1.5rem;
}
.footer-container {
    max-width: 1100px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 2.5rem;
    margin-bottom: 2rem;
}
@media (max-width: 768px) {
    .footer-container { grid-template-columns: 1fr; }
}
.footer-col h3, .footer-col h4 {
    margin-bottom: 1rem;
    color: var(--text-primary);
}
.footer-col p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
}
.footer-col ul { list-style: none; }
.footer-col li { margin-bottom: 0.5rem; }
.footer-col a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    transition: color 0.2s;
}
.footer-col a:hover { color: var(--accent-color); }
.footer-bottom {
    max-width: 1100px;
    margin: 0 auto;
    border-top: 1px solid var(--border-color);
    padding-top: 1.5rem;
    text-align: center;
    color: #6e7681;
    font-size: 0.85rem;
}