@import url('https://fonts.googleapis.com/css2?family=Montserrat:wght@400;600;700;900&family=Roboto:wght@400;500;700&display=swap');

:root {
    --primary-color: #1a3c5e;
    --primary-light: #2b5585;
    --secondary-color: #3cb4b0;
    --accent-color: #ff7e3d;
    --accent-hover: #e56a30;
    --bg-color: #f0f4f8;
    --card-bg: #ffffff;
    --text-color: #2c3e50;
    --text-muted: #546e7a;
    --border-color: #dbe4f0;
    --border-radius: 12px;
    --shadow-sm: 0 2px 8px rgba(26, 60, 94, 0.05);
    --shadow-md: 0 4px 16px rgba(26, 60, 94, 0.08);
    --shadow-lg: 0 8px 24px rgba(26, 60, 94, 0.12);
}

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

body {
    font-family: 'Roboto', sans-serif;
    background: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}

h1, h2, h3, h4, h5, h6 {
    font-family: 'Montserrat', sans-serif;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.container {
    width: 100%;
    max-width: 960px;
    margin: 0 auto;
    padding: 0 24px;
}

header {
    background: #ffffff;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    position: sticky;
    top: 0;
    z-index: 100;
}

header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.logo-text {
    font-family: 'Montserrat', sans-serif;
    font-weight: 900;
    font-size: 2.2rem;
    color: var(--primary-color);
    letter-spacing: -1px;
}

.accent {
    color: var(--accent-color);
}

header h1 {
    margin: 0;
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-color);
    display: none;
}

@media (min-width: 600px) {
    header h1 { display: block; }
}

main {
    padding: 30px 0 60px;
}

.breadcrumb {
    margin-bottom: 24px;
    font-size: 0.95rem;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    gap: 8px;
}

.breadcrumb a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 4px;
    transition: color 0.2s;
}

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

.bc-active {
    color: var(--text-muted);
    font-weight: 400;
}

.card {
    background: var(--card-bg);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    padding: 32px;
    margin-bottom: 30px;
    border: 1px solid rgba(255,255,255,0.7);
}

.calculator-card {
    border-top: 4px solid var(--accent-color);
}

.calculator-card h2 {
    font-size: 1.8rem;
    margin-bottom: 24px;
    text-align: center;
    color: var(--primary-color);
}

.unit-selectors {
    display: flex;
    align-items: flex-end;
    gap: 16px;
    margin-bottom: 24px;
    background: #f8fafc;
    padding: 16px;
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
}

.selector-group {
    flex: 1;
}

.selector-group label {
    display: block;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-muted);
    margin-bottom: 8px;
    font-weight: 700;
}

select {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    font-family: inherit;
    color: var(--text-color);
    background-color: #fff;
    cursor: pointer;
    appearance: none;
    box-shadow: var(--shadow-sm);
    transition: border-color 0.2s;
}

select:focus {
    outline: none;
    border-color: var(--secondary-color);
}

.swap-btn-container {
    padding-bottom: 2px;
}

.btn-tertiary {
    background: #eaeff5;
    color: var(--primary-color);
    border: none;
    padding: 12px;
    border-radius: 8px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

.btn-tertiary:hover {
    background: var(--primary-color);
    color: #fff;
}

.input-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    margin-bottom: 24px;
}

.input-group {
    flex: 1;
    min-width: 200px;
}

.input-group label {
    display: block;
    margin-bottom: 8px;
    color: var(--primary-color);
    font-weight: 600;
    font-size: 0.95rem;
}

.input-wrap {
    position: relative;
    display: flex;
    align-items: center;
}

input[type="number"] {
    width: 100%;
    padding: 14px 60px 14px 16px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1.1rem;
    font-family: inherit;
    transition: border-color 0.2s;
    background: #fff;
    box-shadow: inset 0 1px 3px rgba(0,0,0,0.02);
}

input[type="number"]:focus {
    outline: none;
    border-color: var(--secondary-color);
}

.unit {
    position: absolute;
    right: 16px;
    color: var(--text-muted);
    font-weight: 600;
    font-size: 0.95rem;
}

.btn-row {
    display: flex;
    gap: 16px;
    margin-bottom: 30px;
}

.btn {
    border: none;
    border-radius: 8px;
    padding: 14px 24px;
    font-family: 'Montserrat', sans-serif;
    font-weight: 700;
    font-size: 1rem;
    cursor: pointer;
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: all 0.2s;
}

.btn-primary {
    background: var(--primary-color);
    color: #fff;
    box-shadow: 0 4px 6px rgba(26, 60, 94, 0.2);
}

.btn-primary:hover {
    background: var(--primary-light);
    transform: translateY(-1px);
}

.btn-secondary {
    background: #eef2f6;
    color: var(--primary-color);
    border: 2px solid #dce4ee;
}

.btn-secondary:hover {
    background: #e2eaf2;
    border-color: #cbd5e1;
}

.output-panel {
    background: #f8fafc;
    border-radius: 12px;
    padding: 24px;
    border: 1px solid var(--border-color);
}

.output-group {
    margin-bottom: 20px;
}

.output-group:last-child {
    margin-bottom: 0;
}

.output-group label {
    display: block;
    margin-bottom: 8px;
    color: var(--text-muted);
    font-size: 0.9rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.output-box {
    background: #fff;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    padding: 16px;
    font-size: 1.4rem;
    color: var(--primary-color);
    font-weight: 700;
    min-height: 60px;
    display: flex;
    align-items: center;
    box-shadow: inset 0 1px 2px rgba(0,0,0,0.02);
    word-break: break-all;
}

.steps-box {
    width: 100%;
    min-height: 100px;
    padding: 16px;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    font-family: 'Roboto Mono', monospace;
    font-size: 0.95rem;
    color: #334155;
    background: #fff;
    resize: vertical;
    line-height: 1.5;
}

.steps-box:focus {
    outline: none;
    border-color: var(--secondary-color);
}

.seo-content h2 {
    font-size: 1.5rem;
    border-bottom: 2px solid #f0f4f8;
    padding-bottom: 12px;
    margin-bottom: 20px;
}

.seo-content p {
    margin-bottom: 16px;
    font-size: 1.05rem;
    color: #475569;
}

.seo-content code {
    background: #f1f5f9;
    padding: 6px 12px;
    border-radius: 6px;
    color: var(--primary-color);
    font-family: 'Roboto Mono', monospace;
    font-size: 0.95rem;
    display: inline-block;
    border: 1px solid #e2e8f0;
}

.definition-block {
    margin-bottom: 24px;
    padding: 20px;
    background: #f8fafc;
    border-radius: 8px;
    border-left: 4px solid var(--secondary-color);
}

.definition-block h3 {
    margin-bottom: 8px;
    font-size: 1.2rem;
    color: var(--primary-color);
}

.definition-block p {
    margin: 0;
}

.table-responsive {
    overflow-x: auto;
}

.content-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 16px;
    background: #fff;
}

.content-table th,
.content-table td {
    padding: 14px 16px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.content-table th {
    background: var(--primary-color);
    color: #fff;
    font-weight: 600;
    text-transform: uppercase;
    font-size: 0.85rem;
    letter-spacing: 0.5px;
}

.content-table tr:hover td {
    background: #f8fafc;
}

footer {
    background: var(--primary-color);
    color: #cbd5e1;
    padding: 40px 0;
    text-align: center;
    margin-top: auto;
}

footer a {
    color: #fff;
    text-decoration: none;
    transition: color 0.2s;
    font-weight: 500;
}

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

footer p {
    margin: 0;
    font-size: 0.95rem;
}

@media (max-width: 768px) {
    .unit-selectors {
        flex-direction: column;
        align-items: stretch;
    }
    
    .swap-btn-container {
        display: flex;
        justify-content: center;
        padding: 8px 0;
    }
    
    .btn-row {
        flex-direction: column;
    }
    
    .input-grid {
        flex-direction: column;
        gap: 16px;
    }
}