/* ============================================================
   ConvertBG — Main Stylesheet
   Production-ready, mobile-first, no external CSS frameworks
   ============================================================ */

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

:root {
    /* Colour palette */
    --c-primary:      #4F46E5;
    --c-primary-dark: #3730A3;
    --c-primary-light:#EEF2FF;
    --c-success:      #059669;
    --c-danger:       #DC2626;
    --c-warning:      #D97706;
    --c-text:         #111827;
    --c-text-muted:   #6B7280;
    --c-border:       #E5E7EB;
    --c-bg:           #F9FAFB;
    --c-white:        #FFFFFF;

    /* Spacing */
    --space-xs:  0.25rem;
    --space-sm:  0.5rem;
    --space-md:  1rem;
    --space-lg:  1.5rem;
    --space-xl:  2.5rem;
    --space-xxl: 4rem;

    /* Typography */
    --font-base: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --radius:    0.5rem;
    --shadow-sm: 0 1px 3px rgba(0,0,0,.08);
    --shadow-md: 0 4px 16px rgba(0,0,0,.10);
    --shadow-lg: 0 8px 32px rgba(0,0,0,.12);

    /* Transitions */
    --trans: 0.2s ease;
}

html { font-size: 16px; scroll-behavior: smooth; }

body {
    font-family: var(--font-base);
    color: var(--c-text);
    background: var(--c-bg);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

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

a { color: var(--c-primary); text-decoration: none; transition: color var(--trans); }
a:hover { color: var(--c-primary-dark); }

h1, h2, h3, h4 { line-height: 1.25; font-weight: 700; }

/* ── Layout ──────────────────────────────────────────────── */
.container {
    width: 100%;
    max-width: 1140px;
    margin-inline: auto;
    padding-inline: var(--space-lg);
}

.main-content { flex: 1; }

/* ── Buttons ─────────────────────────────────────────────── */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-family: var(--font-base);
    font-size: 0.9375rem;
    font-weight: 600;
    padding: 0.625rem 1.25rem;
    border-radius: var(--radius);
    border: 2px solid transparent;
    cursor: pointer;
    transition: background var(--trans), color var(--trans), border-color var(--trans), box-shadow var(--trans);
    white-space: nowrap;
    text-decoration: none;
}

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

.btn-success {
    background: var(--c-success);
    color: var(--c-white);
    border-color: var(--c-success);
}
.btn-success:hover { filter: brightness(1.1); color: var(--c-white); }

.btn-outline {
    background: transparent;
    color: var(--c-primary);
    border-color: var(--c-primary);
}
.btn-outline:hover {
    background: var(--c-primary-light);
}

.btn-lg { font-size: 1.0625rem; padding: 0.75rem 1.75rem; border-radius: 0.625rem; }
.btn-sm { font-size: 0.875rem;  padding: 0.4rem 0.9rem; }

.btn:disabled { opacity: 0.55; cursor: not-allowed; pointer-events: none; }

/* ── Header ──────────────────────────────────────────────── */
.site-header {
    background: var(--c-white);
    border-bottom: 1px solid var(--c-border);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-block: 0.875rem;
    gap: var(--space-lg);
}

.logo {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--c-text);
    text-decoration: none;
}
.logo:hover { color: var(--c-primary); }
.logo strong { color: var(--c-primary); }

.main-nav ul {
    list-style: none;
    display: flex;
    gap: var(--space-lg);
    flex-wrap: wrap;
}

.main-nav a {
    color: var(--c-text-muted);
    font-size: 0.9rem;
    font-weight: 500;
    padding: 0.25rem 0;
    border-bottom: 2px solid transparent;
    transition: color var(--trans), border-color var(--trans);
}
.main-nav a:hover,
.main-nav a.active {
    color: var(--c-primary);
    border-bottom-color: var(--c-primary);
}

/* Mobile hamburger */
.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}
.nav-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--c-text);
    border-radius: 2px;
    transition: transform var(--trans), opacity var(--trans);
}

/* ── Hero ────────────────────────────────────────────────── */
.hero {
    background: linear-gradient(135deg, var(--c-primary) 0%, var(--c-primary-dark) 100%);
    color: var(--c-white);
    padding: var(--space-xxl) 0;
    text-align: center;
}

.hero-title {
    font-size: clamp(1.75rem, 5vw, 3rem);
    font-weight: 800;
    margin-bottom: var(--space-md);
    line-height: 1.15;
}

.hero-subtitle {
    font-size: clamp(1rem, 2vw, 1.2rem);
    opacity: 0.9;
    max-width: 560px;
    margin-inline: auto;
    margin-bottom: var(--space-lg);
}

.hero-stats {
    display: inline-block;
    background: rgba(255,255,255,.15);
    backdrop-filter: blur(4px);
    border-radius: 9999px;
    padding: 0.4rem 1.2rem;
    font-size: 0.9rem;
}

/* ── Tool Cards (Homepage) ───────────────────────────────── */
.tools-section {
    padding: var(--space-xxl) 0;
}

.section-title {
    font-size: clamp(1.4rem, 3vw, 1.875rem);
    margin-bottom: var(--space-xl);
    text-align: center;
}

.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: var(--space-lg);
}

.tool-card {
    background: var(--c-white);
    border: 1px solid var(--c-border);
    border-radius: calc(var(--radius) * 2);
    padding: var(--space-xl) var(--space-lg);
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
    transition: box-shadow var(--trans), transform var(--trans), border-color var(--trans);
    color: var(--c-text);
    text-decoration: none;
}
.tool-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-3px);
    border-color: var(--c-primary);
    color: var(--c-text);
}

.tool-icon {
    width: 48px;
    height: 48px;
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--space-sm);
}
.tool-icon svg { width: 24px; height: 24px; }
.tool-icon--image { background: #EEF2FF; color: var(--c-primary); }
.tool-icon--pdf   { background: #FEF2F2; color: #DC2626; }
.tool-icon--merge { background: #F0FDF4; color: #059669; }

.tool-card h3 { font-size: 1.0625rem; }
.tool-card p   { font-size: 0.875rem; color: var(--c-text-muted); line-height: 1.55; flex: 1; }

.tool-card-cta { font-size: 0.875rem; font-weight: 600; color: var(--c-primary); }

/* ── Features ────────────────────────────────────────────── */
.features-section {
    background: var(--c-white);
    padding: var(--space-xxl) 0;
    border-top: 1px solid var(--c-border);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: var(--space-xl);
    text-align: center;
}

.feature-item { display: flex; flex-direction: column; align-items: center; gap: var(--space-md); }
.feature-icon { width: 44px; height: 44px; color: var(--c-primary); }
.feature-item h3 { font-size: 1rem; }
.feature-item p  { font-size: 0.875rem; color: var(--c-text-muted); max-width: 260px; }

/* ── Tool Hero ───────────────────────────────────────────── */
.tool-hero {
    background: linear-gradient(135deg, var(--c-primary) 0%, var(--c-primary-dark) 100%);
    color: var(--c-white);
    padding: var(--space-xl) 0 var(--space-xxl);
}

.breadcrumb ol {
    list-style: none;
    display: flex;
    gap: 0.35rem;
    font-size: 0.85rem;
    margin-bottom: var(--space-md);
    opacity: 0.85;
}
.breadcrumb li + li::before { content: '/'; margin-right: 0.35rem; }
.breadcrumb a { color: rgba(255,255,255,.75); }
.breadcrumb a:hover { color: #fff; }

.tool-hero-title {
    font-size: clamp(1.5rem, 4vw, 2.5rem);
    line-height: 1.15;
    font-weight: 800;
}

/* ── Upload Section ──────────────────────────────────────── */
.upload-section {
    padding: var(--space-xxl) 0;
    margin-top: -2rem;
}

.upload-wrapper {
    background: var(--c-white);
    border-radius: calc(var(--radius) * 2);
    box-shadow: var(--shadow-lg);
    padding: var(--space-xl);
    max-width: 680px;
    margin-inline: auto;
}

/* Drop Zone */
.drop-zone {
    border: 2.5px dashed var(--c-border);
    border-radius: var(--radius);
    background: var(--c-bg);
    padding: var(--space-xl);
    text-align: center;
    cursor: pointer;
    transition: border-color var(--trans), background var(--trans);
    position: relative;
    outline: none;
}
.drop-zone:hover,
.drop-zone.dragover {
    border-color: var(--c-primary);
    background: var(--c-primary-light);
}
.drop-zone:focus-visible { outline: 3px solid var(--c-primary); outline-offset: 2px; }

.file-input {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    cursor: pointer;
    z-index: 1;
}

.drop-zone-inner {
    pointer-events: none;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-md);
}
.drop-zone-inner .btn { pointer-events: all; }

.upload-icon { width: 52px; height: 52px; color: var(--c-primary); opacity: .6; }
.drop-label  { font-size: 1rem; font-weight: 600; color: var(--c-text); }
.drop-hint   { font-size: 0.8125rem; color: var(--c-text-muted); }

/* File Preview */
.file-preview-list {
    text-align: left;
    padding: var(--space-md);
}
.file-preview-item {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-sm) 0;
    border-bottom: 1px solid var(--c-border);
    font-size: 0.875rem;
}
.file-preview-item:last-child { border-bottom: none; }
.file-preview-name { flex: 1; font-weight: 500; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.file-preview-size { color: var(--c-text-muted); white-space: nowrap; }
.file-preview-remove {
    background: none;
    border: none;
    cursor: pointer;
    color: var(--c-danger);
    padding: 2px;
    line-height: 1;
    font-size: 1.1rem;
}

/* Convert area */
.convert-area {
    margin-top: var(--space-lg);
    display: flex;
    justify-content: center;
}

/* Progress */
.progress-area { margin-top: var(--space-lg); }
.progress-bar-wrap {
    background: var(--c-border);
    border-radius: 9999px;
    height: 10px;
    overflow: hidden;
}
.progress-bar-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--c-primary), var(--c-primary-dark));
    border-radius: 9999px;
    width: 0%;
    transition: width 0.3s ease;
}
.progress-label {
    text-align: center;
    margin-top: var(--space-sm);
    font-size: 0.875rem;
    color: var(--c-text-muted);
}

/* Result */
.result-area { margin-top: var(--space-lg); }

.result-success,
.result-error {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    gap: var(--space-md);
    padding: var(--space-xl);
}

.result-icon { width: 56px; height: 56px; }
.result-icon--ok  { color: var(--c-success); }
.result-icon--err { color: var(--c-danger); }

.result-success h2 { color: var(--c-success); }
.result-error  h2  { color: var(--c-danger);  }

#resultFilename { font-size: 0.875rem; color: var(--c-text-muted); }

/* ── SEO Content Section ─────────────────────────────────── */
.seo-section {
    background: var(--c-white);
    border-top: 1px solid var(--c-border);
    padding: var(--space-xxl) 0;
}

.seo-content {
    max-width: 760px;
    margin-inline: auto;
}

.seo-content h2 {
    font-size: 1.5rem;
    margin-bottom: var(--space-lg);
    color: var(--c-text);
}

.seo-content p {
    margin-bottom: var(--space-md);
    color: #374151;
    line-height: 1.75;
    font-size: 0.9625rem;
}

/* ── Related Tools ───────────────────────────────────────── */
.related-tools-section {
    padding: var(--space-xxl) 0;
}

.related-tools-grid {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-md);
}

.related-tool-card {
    background: var(--c-white);
    border: 1px solid var(--c-border);
    border-radius: var(--radius);
    padding: var(--space-sm) var(--space-lg);
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--c-primary);
    transition: background var(--trans), border-color var(--trans);
}
.related-tool-card:hover {
    background: var(--c-primary-light);
    border-color: var(--c-primary);
    color: var(--c-primary);
}

/* ── Footer ──────────────────────────────────────────────── */
.site-footer {
    background: #1F2937;
    color: #D1D5DB;
    margin-top: auto;
}

.footer-inner {
    display: grid;
    grid-template-columns: 1fr auto auto 1fr;
    gap: var(--space-xl);
    padding-block: var(--space-xxl);
    align-items: start;
}

.footer-brand .logo { color: #F9FAFB; margin-bottom: var(--space-sm); }
.footer-brand .logo strong { color: #818CF8; }
.footer-brand .logo:hover { color: #fff; }
.footer-tagline { font-size: 0.875rem; color: #9CA3AF; }

.footer-nav h3 { font-size: 0.8125rem; text-transform: uppercase; letter-spacing: .06em; color: #9CA3AF; margin-bottom: var(--space-md); }
.footer-nav ul { list-style: none; display: flex; flex-direction: column; gap: var(--space-xs); }
.footer-nav a  { color: #D1D5DB; font-size: 0.9rem; transition: color var(--trans); }
.footer-nav a:hover { color: #fff; }

.footer-info { display: flex; flex-direction: column; gap: var(--space-md); }
.footer-info p { font-size: 0.8125rem; color: #9CA3AF; }
.footer-info strong { color: #D1D5DB; }

.footer-bottom {
    border-top: 1px solid #374151;
    padding-block: var(--space-md);
    text-align: center;
    font-size: 0.8125rem;
    color: #6B7280;
}

/* ── Responsive ──────────────────────────────────────────── */
@media (max-width: 860px) {
    .footer-inner { grid-template-columns: 1fr; }
}

@media (max-width: 700px) {
    .nav-toggle { display: flex; }

    .main-nav {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--c-white);
        border-bottom: 1px solid var(--c-border);
        box-shadow: var(--shadow-md);
        padding: var(--space-md) var(--space-lg);
        z-index: 99;
    }
    .main-nav.open { display: block; }
    .main-nav ul { flex-direction: column; gap: var(--space-sm); }
    .main-nav a { font-size: 1rem; padding: 0.4rem 0; }

    .header-inner { position: relative; }
}

@media (max-width: 520px) {
    .upload-wrapper { padding: var(--space-lg); }
    .drop-zone { padding: var(--space-lg); }
    .hero { padding: var(--space-xl) 0; }
    .tools-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 380px) {
    .tools-grid { grid-template-columns: 1fr; }
}

/* ── Utility ─────────────────────────────────────────────── */
.visually-hidden {
    position: absolute;
    width: 1px; height: 1px;
    padding: 0; margin: -1px;
    overflow: hidden; clip: rect(0,0,0,0);
    white-space: nowrap; border: 0;
}

/* Spinning loader (used in progress state) */
@keyframes spin { to { transform: rotate(360deg); } }
.spinner {
    display: inline-block;
    width: 18px; height: 18px;
    border: 2.5px solid rgba(255,255,255,.4);
    border-top-color: #fff;
    border-radius: 50%;
    animation: spin .6s linear infinite;
}