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

:root {
    --bg-primary: #1a1a2e;
    --bg-secondary: #16213e;
    --bg-card: #0f3460;
    --bg-input: #16213e;
    --text-primary: #e0e0e0;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --accent: #00d4ff;
    --accent-hover: #00b8e6;
    --border: #1f4a6e;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
}

.app {
    display: flex;
    min-height: 100vh;
}

.sidebar {
    width: 260px;
    background: var(--bg-secondary);
    padding: 24px;
    position: fixed;
    height: 100vh;
    border-right: 1px solid var(--border);
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 40px;
}

.logo-icon {
    font-size: 28px;
}

.logo-text {
    font-size: 20px;
    font-weight: 700;
    color: var(--text-primary);
}

.nav-menu {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.nav-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    border-radius: 8px;
    color: var(--text-secondary);
    text-decoration: none;
    transition: all 0.2s;
}

.nav-item:hover {
    background: var(--bg-card);
    color: var(--text-primary);
}

.nav-item.active {
    background: var(--accent);
    color: #1a1a2e;
}

.nav-icon {
    font-size: 18px;
}

.main-content {
    flex: 1;
    margin-left: 260px;
    padding: 24px 40px;
}

.header {
    display: flex;
    justify-content: flex-end;
    margin-bottom: 40px;
}

.search-box input {
    width: 300px;
    padding: 12px 16px;
    border-radius: 8px;
    border: 1px solid var(--border);
    background: var(--bg-card);
    color: var(--text-primary);
    font-size: 14px;
}

.search-box input::placeholder {
    color: var(--text-muted);
}

.search-box input:focus {
    outline: none;
    border-color: var(--accent);
}

.page-title {
    font-size: 32px;
    font-weight: 700;
    margin-bottom: 8px;
}

.page-desc {
    color: var(--text-secondary);
    margin-bottom: 40px;
}

.tool-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 24px;
}

.tool-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 24px;
    text-decoration: none;
    transition: all 0.3s;
}

.tool-card:hover {
    border-color: var(--accent);
    transform: translateY(-4px);
    box-shadow: 0 10px 40px rgba(0,0,0,0.3);
}

.card-icon {
    font-size: 48px;
    margin-bottom: 16px;
}

.card-title {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.card-desc {
    font-size: 14px;
    color: var(--text-secondary);
}

.calculator {
    max-width: 600px;
    background: var(--bg-card);
    border-radius: 12px;
    padding: 32px;
    border: 1px solid var(--border);
}

.calc-form {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 24px;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.input-group label {
    font-size: 14px;
    color: var(--text-secondary);
}

.input-group input,
.input-group select {
    padding: 12px 16px;
    border-radius: 8px;
    border: 1px solid var(--border);
    background: var(--bg-input);
    color: var(--text-primary);
    font-size: 16px;
}

.input-group input:focus,
.input-group select:focus {
    outline: none;
    border-color: var(--accent);
}

.calc-btn {
    width: 100%;
    padding: 14px;
    border-radius: 8px;
    border: none;
    background: var(--accent);
    color: #1a1a2e;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s;
    margin-bottom: 24px;
}

.calc-btn:hover {
    background: var(--accent-hover);
}

.calc-result {
    background: var(--bg-secondary);
    border-radius: 8px;
    padding: 24px;
    text-align: center;
    font-size: 18px;
    color: var(--accent);
    margin-bottom: 24px;
}

.formula-info {
    display: flex;
    justify-content: center;
    gap: 24px;
}

.formula {
    padding: 8px 16px;
    background: var(--bg-secondary);
    border-radius: 6px;
    font-family: 'Courier New', monospace;
    color: var(--text-secondary);
}

.color-bands {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin-bottom: 24px;
}

.band-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.band-group label {
    font-size: 14px;
    color: var(--text-secondary);
}

.color-select {
    padding: 10px 12px;
    border-radius: 6px;
    border: 1px solid var(--border);
    background: var(--bg-input);
    color: var(--text-primary);
    font-size: 14px;
}

.mode-toggle {
    display: flex;
    gap: 8px;
    margin-bottom: 24px;
}

.mode-btn {
    flex: 1;
    padding: 12px;
    border-radius: 8px;
    border: 1px solid var(--border);
    background: var(--bg-card);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s;
}

.mode-btn.active {
    background: var(--accent);
    color: #1a1a2e;
    border-color: var(--accent);
}

.hidden {
    display: none;
}

@media (max-width: 768px) {
    .sidebar {
        width: 100%;
        position: relative;
        height: auto;
        padding: 16px;
    }
    
    .main-content {
        margin-left: 0;
        padding: 24px;
    }
    
    .app {
        flex-direction: column;
    }
    
    .calc-form {
        grid-template-columns: 1fr;
    }
}