/* ===== CSS Custom Properties ===== */
:root {
    --color-bg: #faf7f2;
    --color-surface: #ffffff;
    --color-text: #2e241b;
    --color-text-secondary: #6b5e53;
    --color-accent: #b5835a;
    --color-accent-hover: #9c6f48;
    --color-border: #e5dbcf;
    --color-tab-bg: #f0e8dc;
    --color-tab-active-bg: #ffffff;
    --color-input-bg: #fdfbf7;
    --color-result-bg: #f6f0e6;
    --shadow-sm: 0 1px 3px rgba(46, 36, 27, 0.06);
    --shadow-md: 0 4px 12px rgba(46, 36, 27, 0.08);
    --shadow-lg: 0 8px 24px rgba(46, 36, 27, 0.1);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --font-sans: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif;
    --font-mono: 'SF Mono', 'Cascadia Code', 'Fira Code', monospace;
    --transition: 0.2s ease;
}

/* ===== Reset & Base ===== */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 100%;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img, svg {
    display: block;
    max-width: 100%;
}

a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color var(--transition);
}

a:hover {
    color: var(--color-accent-hover);
    text-decoration: underline;
}

button {
    cursor: pointer;
    border: none;
    background: none;
    font-family: inherit;
    font-size: inherit;
}

input, select {
    font-family: inherit;
    font-size: inherit;
}

/* ===== Container ===== */
.container {
    width: 100%;
    max-width: 720px;
    margin-left: auto;
    margin-right: auto;
    padding-left: 1.25rem;
    padding-right: 1.25rem;
}

/* ===== Header ===== */
.site-header {
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    padding: 0.75rem 0;
    position: sticky;
    top: 0;
    z-index: 10;
    box-shadow: var(--shadow-sm);
}

.logo {
    display: inline-flex;
    align-items: center;
    gap: 0.625rem;
    font-weight: 700;
    font-size: 1.15rem;
    color: var(--color-text);
    text-decoration: none;
    letter-spacing: -0.01em;
}

.logo:hover {
    text-decoration: none;
    color: var(--color-accent);
}

.logo svg {
    flex-shrink: 0;
}

/* ===== Hero ===== */
.hero {
    padding: 2.5rem 0 1.5rem;
    text-align: center;
}

.hero h1 {
    font-size: clamp(1.8rem, 5vw, 2.5rem);
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.2;
    color: var(--color-text);
    margin-bottom: 0.5rem;
}

.hero-sub {
    font-size: 1.1rem;
    color: var(--color-text-secondary);
    max-width: 400px;
    margin: 0 auto;
}

/* ===== Converter Card ===== */
.converter-section {
    padding: 0 0 2rem;
}

.converter-card {
    background: var(--color-surface);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    overflow: hidden;
    border: 1px solid var(--color-border);
}

/* Tabs */
.category-tabs {
    display: flex;
    background: var(--color-tab-bg);
    border-bottom: 1px solid var(--color-border);
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

.tab {
    flex: 1 0 auto;
    padding: 0.85rem 1rem;
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--color-text-secondary);
    border-bottom: 3px solid transparent;
    transition: all var(--transition);
    white-space: nowrap;
    background: transparent;
}

.tab:hover {
    color: var(--color-text);
    background: rgba(181, 131, 90, 0.06);
}

.tab.active {
    color: var(--color-accent);
    border-bottom-color: var(--color-accent);
    background: var(--color-tab-active-bg);
}

/* Body */
.converter-body {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
}

.input-label,
.unit-label {
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--color-text-secondary);
}

.value-input {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1.5px solid var(--color-border);
    border-radius: var(--radius-sm);
    background: var(--color-input-bg);
    font-size: 1.3rem;
    font-weight: 500;
    color: var(--color-text);
    transition: border-color var(--transition), box-shadow var(--transition);
    -moz-appearance: textfield;
}

.value-input::-webkit-outer-spin-button,
.value-input::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

.value-input:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(181, 131, 90, 0.15);
}

/* Unit selectors */
.unit-selectors {
    display: flex;
    align-items: flex-end;
    gap: 0.75rem;
}

.unit-group {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
}

.unit-select {
    width: 100%;
    padding: 0.7rem 0.75rem;
    border: 1.5px solid var(--color-border);
    border-radius: var(--radius-sm);
    background: var(--color-input-bg);
    font-weight: 500;
    color: var(--color-text);
    cursor: pointer;
    transition: border-color var(--transition);
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg width='10' height='6' viewBox='0 0 10 6' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M1 1l4 4 4-4' stroke='%236b5e53' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.75rem center;
    padding-right: 2.2rem;
}

.unit-select:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(181, 131, 90, 0.15);
}

/* Swap button */
.swap-btn {
    flex-shrink: 0;
    width: 42px;
    height: 42px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    background: var(--color-tab-bg);
    color: var(--color-accent);
    border: 1.5px solid var(--color-border);
    transition: all var(--transition);
    margin-bottom: 0;
    align-self: flex-end;
}

.swap-btn:hover {
    background: var(--color-accent);
    color: #fff;
    border-color: var(--color-accent);
    transform: rotate(180deg);
}

/* Result */
.result-box {
    background: var(--color-result-bg);
    border-radius: var(--radius-md);
    padding: 1.25rem 1.5rem;
    display: flex;
    align-items: baseline;
    gap: 0.5rem;
    flex-wrap: wrap;
    border: 1px solid var(--color-border);
}

.result-label {
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--color-text-secondary);
    margin-right: 0.25rem;
}

.result-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--color-text);
    font-family: var(--font-mono);
    letter-spacing: -0.02em;
    word-break: break-word;
}

.result-unit {
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--color-text-secondary);
}

/* ===== Features ===== */
.info-section {
    padding: 2rem 0;
}

.info-section h2 {
    text-align: center;
    font-size: 1.6rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    letter-spacing: -0.01em;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.25rem;
}

.feature-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: 1.25rem;
    box-shadow: var(--shadow-sm);
    transition: box-shadow var(--transition), transform var(--transition);
}

.feature-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.feature-icon {
    margin-bottom: 0.75rem;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-tab-bg);
    border-radius: var(--radius-sm);
}

.feature-card h3 {
    font-size: 1.05rem;
    font-weight: 650;
    margin-bottom: 0.35rem;
}

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

/* ===== Common Table ===== */
.usage-section {
    padding: 1.5rem 0 2.5rem;
}

.usage-section h2 {
    text-align: center;
    font-size: 1.6rem;
    font-weight: 700;
    margin-bottom: 1.25rem;
    letter-spacing: -0.01em;
}

.table-wrapper {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    border-radius: var(--radius-md);
    border: 1px solid var(--color-border);
    background: var(--color-surface);
    box-shadow: var(--shadow-sm);
}

.common-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.9rem;
    min-width: 400px;
}

.common-table th {
    background: var(--color-tab-bg);
    padding: 0.75rem 1rem;
    text-align: left;
    font-weight: 650;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--color-text-secondary);
    border-bottom: 1px solid var(--color-border);
}

.common-table td {
    padding: 0.7rem 1rem;
    border-bottom: 1px solid var(--color-border);
    color: var(--color-text);
}

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

.common-table tbody tr:hover {
    background: rgba(181, 131, 90, 0.04);
}

.table-note {
    text-align: center;
    font-size: 0.85rem;
    color: var(--color-text-secondary);
    margin-top: 0.75rem;
}

/* ===== Footer ===== */
.site-footer {
    margin-top: auto;
    background: var(--color-surface);
    border-top: 1px solid var(--color-border);
    padding: 1.25rem 0;
}

.site-footer .container {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem;
}

.footer-text {
    font-size: 0.85rem;
    color: var(--color-text-secondary);
}

.footer-nav {
    display: flex;
    gap: 1.25rem;
}

.footer-nav a {
    font-size: 0.85rem;
    font-weight: 500;
}

/* ===== Responsive ===== */
@media (max-width: 600px) {
    .converter-body {
        padding: 1.25rem 1rem;
        gap: 1rem;
    }

    .unit-selectors {
        flex-wrap: wrap;
    }

    .swap-btn {
        align-self: center;
        margin-top: 0.5rem;
    }

    .result-value {
        font-size: 1.6rem;
    }

    .hero {
        padding: 2rem 0 1rem;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .category-tabs {
        gap: 0;
    }

    .tab {
        padding: 0.75rem 0.85rem;
        font-size: 0.85rem;
    }
}

@media (min-width: 601px) and (max-width: 900px) {
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Legal pages */
.legal-page {
    padding: 3rem 0;
    max-width: 680px;
    margin: 0 auto;
}

.legal-page h1 {
    font-size: 1.8rem;
    margin-bottom: 1.5rem;
}

.legal-content {
    font-size: 0.95rem;
    line-height: 1.7;
    color: var(--color-text-secondary);
}

.legal-content a {
    text-decoration: underline;
}

/* Ad slot placeholder styling – hidden by default, shown when real ad is inserted */
#ad-slot-placeholder {
    display: none;
}



/* Factory-injected deployment helpers. The AI owns the site design above this block. */
.ad-unit {
  width: min(100%, 720px);
  min-height: 120px;
  margin: 24px auto;
  display: block;
}

.legal-page {
  width: min(900px, calc(100% - 32px));
  margin: 40px auto;
}