/* Modern String Calculator Styles */

:root {
    --primary-color: #2c1810;
    --secondary-color: #5d4e37;
    --accent-color: #8B4513;
    --background-color: #f9f7f4;
    --card-background: #fefcf9;
    --text-color: #2c1810;
    --border-color: #d4c4a8;
    --success-color: #4a5c2a;
    --warning-color: #a0522d;
    --table-header: #e8dcc0;
    --form-background: #f4f0e8;
    --shadow: 0 1px 3px rgba(44,24,16,0.15);
    --border-radius: 3px;
    --transition: all 0.2s ease;
}

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

body {
    font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.5;
    font-size: 14px;
}

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

/* Header */
.app-header {
    background: var(--background-color);
    color: var(--primary-color);
    padding: 2rem 0;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
}

.app-header h1 {
    font-size: 2.2rem;
    margin-bottom: 0.5rem;
    font-weight: 400;
    letter-spacing: -0.5px;
}

.app-header p {
    font-size: 1rem;
    color: var(--secondary-color);
    font-weight: 400;
}

/* Navigation */
.instrument-nav {
    background: var(--background-color);
    border-bottom: 1px solid var(--border-color);
    padding: 0 2rem;
}

.nav-tabs {
    display: flex;
    gap: 0;
    max-width: 1400px;
    margin: 0 auto;
}

.nav-tab {
    background: none;
    border: none;
    padding: 1rem 1.5rem;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 400;
    color: var(--secondary-color);
    border-bottom: 2px solid transparent;
    transition: var(--transition);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.nav-tab:hover {
    color: var(--primary-color);
}

.nav-tab.active {
    color: var(--primary-color);
    border-bottom-color: var(--accent-color);
    font-weight: 500;
}

/* Main Content */
.main-content {
    display: flex;
    flex: 1;
    max-width: 1400px;
    margin: 0 auto;
    padding: 1.5rem;
    gap: 1.5rem;
}

/* Sidebar */
.instrument-sidebar {
    flex: 0 0 280px;
    background: var(--card-background);
    height: fit-content;
    border-right: 1px solid var(--border-color);
}

.instrument-list {
    padding: 1.5rem;
}

.instrument-list h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.5rem;
}

.instrument-item {
    display: block;
    width: 100%;
    padding: 0.75rem 0;
    margin-bottom: 0.25rem;
    background: none;
    border: none;
    cursor: pointer;
    text-align: left;
    color: var(--secondary-color);
    transition: var(--transition);
    font-size: 0.9rem;
    font-weight: 400;
    border-bottom: 1px solid transparent;
}

.instrument-item:hover {
    color: var(--primary-color);
}

.instrument-item.active {
    color: var(--primary-color);
    font-weight: 500;
    border-bottom-color: var(--accent-color);
}

/* Calculator Section */
.calculator-section {
    flex: 1;
    background: var(--card-background);
}

.calculator-container {
    padding: 2rem 2rem 2rem 1rem;
}

/* Welcome Message */
.welcome-message {
    text-align: left;
    padding: 2rem 0;
}

.welcome-message h2 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.8rem;
    font-weight: 400;
    letter-spacing: -0.3px;
}

.welcome-message > p {
    font-size: 1rem;
    color: var(--secondary-color);
    margin-bottom: 2rem;
    max-width: 600px;
    line-height: 1.6;
}

.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.feature {
    text-align: left;
    padding: 1.5rem;
    background: var(--form-background);
    border: 1px solid var(--border-color);
}

.feature h3 {
    color: var(--primary-color);
    margin-bottom: 0.75rem;
    font-size: 1.1rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.feature p {
    color: var(--secondary-color);
    line-height: 1.5;
    font-size: 0.9rem;
}

/* Calculator Form */
.calculator-form {
    max-width: 900px;
}

.calculator-header {
    text-align: left;
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.calculator-header h2 {
    color: var(--primary-color);
    font-size: 1.6rem;
    margin-bottom: 0.5rem;
    font-weight: 400;
    letter-spacing: -0.3px;
}

.calculator-header p {
    color: var(--secondary-color);
    font-size: 0.9rem;
    margin: 0;
    font-weight: 400;
}

.calculator-controls {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
    padding: 1.5rem;
    background: var(--form-background);
    border: 1px solid var(--border-color);
}

.control-group {
    display: flex;
    flex-direction: column;
}

.control-group label {
    font-weight: 500;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.control-group select,
.control-group input {
    padding: 0.6rem;
    border: 1px solid var(--border-color);
    font-size: 0.9rem;
    transition: var(--transition);
    background: var(--card-background);
    font-weight: 400;
}

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

.control-group small {
    margin-top: 0.3rem;
    color: var(--secondary-color);
    font-size: 0.75rem;
    font-weight: 400;
}

/* Results Table */
.results-container {
    margin-top: 1.5rem;
}

.results-table {
    width: 100%;
    border-collapse: collapse;
    border: 1px solid var(--border-color);
}

.results-table th {
    background: var(--table-header);
    color: var(--primary-color);
    padding: 0.75rem;
    text-align: left;
    font-weight: 500;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    border-bottom: 1px solid var(--border-color);
}

.results-table td {
    padding: 0.75rem;
    border-bottom: 1px solid var(--border-color);
    background: var(--card-background);
    vertical-align: middle;
}

.results-table tr:hover td {
    background: var(--form-background);
}

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

.results-table .string-name {
    font-weight: 500;
    color: var(--primary-color);
    font-size: 0.9rem;
}

.results-table .frequency {
    font-family: Georgia, 'Times New Roman', serif;
    color: var(--secondary-color);
    font-weight: 400;
    font-size: 0.9rem;
}

.results-table .tension-input {
    width: 70px;
    padding: 0.4rem;
    border: 1px solid var(--border-color);
    text-align: center;
    font-weight: 400;
    background: var(--card-background);
    transition: var(--transition);
    font-size: 0.85rem;
}

.results-table .tension-input:focus {
    outline: none;
    border-color: var(--accent-color);
}

.results-table .diameter {
    font-weight: 500;
    color: var(--accent-color);
    font-family: Georgia, 'Times New Roman', serif;
    font-size: 0.9rem;
}

.results-table .diameter.calculated {
    background: #f0f4e8;
    padding: 0.3rem 0.5rem;
    color: var(--success-color);
    font-weight: 600;
}

.results-placeholder {
    color: #6c757d;
    font-style: italic;
    font-size: 0.85rem;
    font-weight: 500;
}

.results-table .diameter .results-placeholder {
    padding: 0.3rem 0.5rem;
    background: var(--form-background);
    border-radius: 4px;
    border: 1px dashed var(--border-color);
}

/* Action Buttons */
.calculator-actions {
    display: flex;
    gap: 1rem;
    justify-content: flex-start;
    margin-top: 2rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.btn {
    padding: 0.7rem 1.5rem;
    border: 1px solid var(--border-color);
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    display: inline-block;
    text-align: center;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    background: var(--card-background);
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

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

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

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

/* Error Messages */
.error-message {
    background: #fee;
    color: var(--accent-color);
    padding: 1rem;
    border-radius: var(--border-radius);
    border: 1px solid #fcc;
    margin: 1rem 0;
    text-align: center;
}

/* Responsive Design */
@media (max-width: 768px) {
    .main-content {
        flex-direction: column;
        padding: 1rem;
    }
    
    .instrument-sidebar {
        flex: none;
        margin-bottom: 1rem;
    }
    
    .nav-tabs {
        flex-wrap: wrap;
    }
    
    .nav-tab {
        flex: 1;
        min-width: 120px;
    }
    
    .calculator-controls {
        grid-template-columns: 1fr;
    }
    
    .app-header h1 {
        font-size: 2rem;
    }
    
    .features {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .main-content {
        padding: 0.5rem;
    }
    
    .calculator-container {
        padding: 1rem;
    }
    
    .app-header {
        padding: 1rem 0;
    }
    
    .app-header h1 {
        font-size: 1.5rem;
    }
    
    .results-table {
        font-size: 0.9rem;
    }
    
    .results-table th,
    .results-table td {
        padding: 0.5rem;
    }
}