/* Minimalist & High-Trust Stylesheet for FahrenheitToCelsius.site */

:root {
    --bg-light: #f8fafc;
    --card-bg: #ffffff;
    --border-color: #e2e8f0;
    --border-focus: #2563eb;
    
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #64748b;
    
    /* Elegant temperature accents */
    --cold-color: #3b82f6;
    --neutral-color: #8b5cf6;
    --hot-color: #ef4444;
    --current-accent: var(--neutral-color);
    
    --font-heading: 'Outfit', sans-serif;
    --font-body: 'Inter', sans-serif;
}

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

body {
    background-color: var(--bg-light);
    color: var(--text-primary);
    font-family: var(--font-body);
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.app-header {
    padding: 2.5rem 1.5rem 1.5rem 1.5rem;
    display: flex;
    justify-content: center;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo .icon {
    font-size: 1.8rem;
}

.logo h1 {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    color: var(--text-primary);
}

/* Main Container */
.main-container {
    max-width: 800px;
    width: 100%;
    margin: 0 auto;
    padding: 0 1.5rem 4rem 1.5rem;
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 2.5rem;
}

/* Clean UI Card */
.app-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 2rem;
    box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.05), 0 1px 2px -1px rgba(0, 0, 0, 0.05);
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.card-header {
    text-align: center;
    margin-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1.25rem;
}

.card-header h2 {
    font-family: var(--font-heading);
    font-size: 1.4rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.card-header p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Inputs Grid */
.converter-grid {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    align-items: center;
    gap: 1.5rem;
    margin-bottom: 2rem;
}

@media (max-width: 640px) {
    .converter-grid {
        grid-template-columns: 1fr;
        gap: 0.75rem;
    }
    .sync-container {
        transform: rotate(90deg);
        margin: 0.25rem 0;
    }
}

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

.input-group label {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

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

.input-wrapper input {
    width: 100%;
    padding: 1rem 3.5rem 1rem 1.25rem;
    font-size: 1.75rem;
    font-family: var(--font-heading);
    font-weight: 600;
    color: var(--text-primary);
    background: #ffffff;
    border: 1.5px solid #cbd5e1;
    border-radius: 12px;
    outline: none;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

/* Hide spin arrows in inputs */
.input-wrapper input::-webkit-outer-spin-button,
.input-wrapper input::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

.input-wrapper input[type=number] {
    -moz-appearance: textfield;
}

.input-wrapper input:focus {
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.unit-badge {
    position: absolute;
    right: 1.25rem;
    font-family: var(--font-heading);
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-muted);
    pointer-events: none;
}

.sync-container {
    display: flex;
    justify-content: center;
    align-items: center;
}

.sync-icon {
    font-size: 1.4rem;
    color: var(--text-muted);
    background: #f1f5f9;
    width: 2.75rem;
    height: 2.75rem;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    border: 1px solid var(--border-color);
    cursor: default;
    transition: transform 0.6s cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* Visual Temperature Slider */
.temp-bar-container {
    margin-bottom: 2rem;
}

.temp-indicator-label {
    display: flex;
    justify-content: space-between;
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

#temp-label-value {
    color: var(--text-primary);
    font-weight: 600;
}

.temp-bar-track {
    height: 8px;
    background: #f1f5f9;
    border-radius: 4px;
    position: relative;
    border: 1px solid var(--border-color);
}

.temp-bar-fill {
    height: 100%;
    width: 50%;
    background: linear-gradient(90deg, var(--cold-color) 0%, var(--neutral-color) 50%, var(--hot-color) 100%);
    border-radius: 4px;
    opacity: 0.9;
    transition: width 0.4s cubic-bezier(0.1, 0.8, 0.25, 1);
}

.temp-bar-pointer {
    width: 18px;
    height: 18px;
    background: #ffffff;
    border: 3px solid var(--current-accent);
    border-radius: 50%;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.15);
    transition: left 0.4s cubic-bezier(0.1, 0.8, 0.25, 1), border-color 0.4s ease;
}

/* Formula Box */
.formula-box {
    background: #f8fafc;
    border-radius: 10px;
    padding: 0.75rem;
    text-align: center;
    border: 1px dashed var(--border-color);
}

.formula-box p {
    font-size: 0.85rem;
    color: var(--text-secondary);
    font-weight: 500;
}

/* Quick Tables */
.section-title {
    text-align: center;
    margin-bottom: 1.5rem;
}

.section-title h3 {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.section-title p {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.tables-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

@media (max-width: 640px) {
    .tables-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
}

.table-card {
    padding: 1.5rem;
}

.table-card h4 {
    font-family: var(--font-heading);
    font-size: 1rem;
    margin-bottom: 1rem;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.5rem;
    color: var(--text-primary);
}

.conversion-table {
    width: 100%;
    border-collapse: collapse;
}

.conversion-table th {
    text-align: left;
    padding: 0.5rem 0.75rem;
    color: var(--text-muted);
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-weight: 600;
    border-bottom: 1px solid var(--border-color);
}

.conversion-table td {
    padding: 0.65rem 0.75rem;
    font-size: 0.85rem;
    border-bottom: 1px solid #f1f5f9;
    color: var(--text-primary);
}

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

.clickable-row {
    cursor: pointer;
    transition: background-color 0.15s ease, transform 0.15s ease;
}

.clickable-row:hover {
    background-color: #f8fafc;
    transform: translateX(2px);
}

/* FAQ & Content */
.info-card h3 {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    text-align: center;
}

.section-subtitle {
    color: var(--text-muted);
    font-size: 0.85rem;
    text-align: center;
    max-width: 600px;
    margin: 0 auto 1.5rem auto;
}

.faq-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    border-top: 1px solid var(--border-color);
    padding-top: 1.5rem;
}

.faq-item {
    padding: 1rem 0;
    border-bottom: 1px solid #f1f5f9;
}

.faq-item:last-child {
    border-bottom: none;
    padding-bottom: 0;
}

.faq-item h5 {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.faq-item p {
    color: var(--text-secondary);
    font-size: 0.85rem;
    margin-bottom: 0.5rem;
}

.faq-item p strong {
    color: var(--text-primary);
}

.math-block {
    background: #f1f5f9;
    border-radius: 8px;
    padding: 0.75rem 1rem;
    font-family: 'Courier New', Courier, monospace;
    font-weight: 600;
    font-size: 1rem;
    text-align: center;
    color: var(--border-focus);
    margin: 0.75rem 0;
    border: 1px solid var(--border-color);
}

/* Footer */
.app-footer {
    padding: 2rem 1.5rem;
    text-align: center;
    border-top: 1px solid var(--border-color);
    background: #ffffff;
    margin-top: auto;
}

.app-footer p {
    color: var(--text-muted);
    font-size: 0.8rem;
}

/* Sync animation */
@keyframes sync-rotate {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(180deg); }
}

.sync-rotate-anim {
    animation: sync-rotate 0.4s ease-out;
}