:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --text-color: #1f2937;
    --text-light: #6b7280;
    --background: #ffffff;
    --background-alt: #f9fafb;
    --border-color: #e5e7eb;
    --success-color: #10b981;
    --error-color: #ef4444;
    --radius: 0.5rem;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

.dark-mode {
    --primary-color: #6366f1;
    --primary-hover: #818cf8;
    --text-color: #f9fafb;
    --text-light: #9ca3af;
    --background: #111827;
    --background-alt: #1f2937;
    --border-color: #374151;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--background);
    color: var(--text-color);
    line-height: 1.5;
    transition: background-color 0.3s, color 0.3s;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 0;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 2rem;
}

.logo h1 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
}

.logo p {
    font-size: 0.875rem;
    color: var(--text-light);
}

.theme-toggle button {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: var(--background-alt);
    border: 1px solid var(--border-color);
    padding: 0.5rem 1rem;
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 0.875rem;
    color: var(--text-color);
    transition: all 0.2s;
}

.theme-toggle button:hover {
    background: var(--border-color);
}

main {
    margin-bottom: 2rem;
}

.converter-container {
    background-color: var(--background-alt);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
}

.converter-nav {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    padding: 1rem;
    background-color: var(--background);
    border-bottom: 1px solid var(--border-color);
}

.nav-btn {
    padding: 0.5rem 1rem;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 0.875rem;
    color: var(--text-color);
    transition: all 0.2s;
}

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

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

.converter-content {
    padding: 1.5rem;
}

.converter-section {
    display: none;
}

.converter-section.active {
    display: block;
}

.converter-section h2 {
    margin-bottom: 1.5rem;
    font-size: 1.5rem;
    font-weight: 600;
}

.converter-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.input-group label {
    font-size: 0.875rem;
    font-weight: 500;
}

.input-group input {
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    font-size: 1rem;
    background-color: var(--background);
    color: var(--text-color);
    width: 100%;
}

.select-group {
    display: flex;
    gap: 1rem;
    align-items: flex-end;
}

.from-group, .to-group {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.from-group label, .to-group label {
    font-size: 0.875rem;
    font-weight: 500;
}

.from-group select, .to-group select {
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    font-size: 1rem;
    background-color: var(--background);
    color: var(--text-color);
    width: 100%;
}

.swap-btn button {
    padding: 0.75rem;
    background-color: var(--background);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    cursor: pointer;
    color: var(--text-color);
    transition: all 0.2s;
}

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

.result-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.result-group label {
    font-size: 0.875rem;
    font-weight: 500;
}

.result {
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    font-size: 1rem;
    background-color: var(--background);
    color: var(--text-color);
    min-height: 2.75rem;
    display: flex;
    align-items: center;
}

.note {
    font-size: 0.75rem;
    color: var(--text-light);
    margin-top: 0.5rem;
}

.input-with-unit {
    display: flex;
    gap: 0.5rem;
}

.input-with-unit input {
    flex: 1;
}

.input-with-unit select {
    width: 80px;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    font-size: 1rem;
    background-color: var(--background);
    color: var(--text-color);
}

.calculate-btn {
    padding: 0.75rem;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    transition: all 0.2s;
}

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

.tabs {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.tab-btn {
    padding: 0.5rem 1rem;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 0.875rem;
    color: var(--text-color);
    transition: all 0.2s;
}

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

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

.tab-content {
    display: none;
}

.tab-content.active {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

footer {
    text-align: center;
    padding: 1.5rem 0;
    border-top: 1px solid var(--border-color);
    color: var(--text-light);
    font-size: 0.875rem;
}

/* Responsive styles */
@media (max-width: 768px) {
    .select-group {
        flex-direction: column;
        gap: 1rem;
    }
    
    .swap-btn {
        align-self: center;
    }
    
    .swap-btn button {
        transform: rotate(90deg);
    }
}

@media (max-width: 480px) {
    .converter-nav {
        justify-content: center;
    }
    
    .nav-btn {
        flex: 1 0 calc(33.333% - 0.5rem);
        text-align: center;
    }
}