/* ===================================
   VARIABLES & RESET
   =================================== */
:root {
  --primary: #4f46e5;
  --primary-dark: #3730a3;
  --primary-light: #818cf8;
  --accent: #7c3aed;
  --bg: #f8fafc;
  --bg-card: #ffffff;
  --text: #0f172a;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --success: #10b981;
  --error: #ef4444;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.07), 0 2px 4px -2px rgb(0 0 0 / 0.07);
  --shadow-lg: 0 10px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
}

/* ===================================
   HEADER
   =================================== */
header {
  background: linear-gradient(135deg, var(--primary) 0%, var(--accent) 100%);
  color: #fff;
  padding: 14px 0;
  box-shadow: 0 2px 8px rgb(79 70 229 / 0.3);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

header nav a {
  color: rgb(255 255 255 / 0.85);
  text-decoration: none;
  font-size: 0.875rem;
  transition: color 0.2s;
}

header nav a:hover { color: #fff; }

/* ===================================
   ADS
   =================================== */
.ad-container { text-align: center; }
.ad-label {
  font-size: 0.65rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 4px;
}
.ad-top {
  padding: 16px 0 8px;
  background: #f1f5f9;
  border-bottom: 1px solid var(--border);
}
.ad-below-result {
  margin-top: 24px;
  padding: 16px;
  background: #f8fafc;
  border-radius: var(--radius-sm);
  border: 1px dashed var(--border);
}
.ad-sidebar {
  background: #f8fafc;
  border-radius: var(--radius-sm);
  border: 1px dashed var(--border);
  padding: 12px;
}
.sticky-ad { position: sticky; top: 20px; }

/* ===================================
   MAIN
   =================================== */
main { padding: 32px 16px 48px; }

.hero { text-align: center; margin-bottom: 28px; }
.hero h1 {
  font-size: clamp(1.5rem, 4vw, 2.25rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  color: var(--text);
  line-height: 1.2;
  margin-bottom: 10px;
}
.hero-desc {
  color: var(--text-muted);
  font-size: 1rem;
  max-width: 580px;
  margin: 0 auto;
}

/* ===================================
   TOOL LAYOUT
   =================================== */
.tool-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
  margin-bottom: 48px;
}
@media (min-width: 1024px) {
  .tool-layout {
    grid-template-columns: 1fr 320px;
    align-items: start;
  }
}

.tool-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  padding: 28px;
  border: 1px solid var(--border);
}

/* ===================================
   UPLOAD ZONE
   =================================== */
.upload-zone {
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  padding: 40px 20px;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
  background: var(--bg);
}
.upload-zone:hover,
.upload-zone.drag-over {
  border-color: var(--primary);
  background: rgb(79 70 229 / 0.04);
}
.upload-zone.drag-over { border-style: solid; }

.upload-inner { display: flex; flex-direction: column; align-items: center; gap: 10px; }
.upload-title { font-size: 1rem; font-weight: 600; color: var(--text); }
.upload-sub { font-size: 0.875rem; color: var(--text-muted); }
.upload-hint { font-size: 0.8rem; color: var(--text-muted); }

.btn-upload {
  padding: 10px 24px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.9375rem;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.15s;
  box-shadow: 0 4px 12px rgb(79 70 229 / 0.3);
}
.btn-upload:hover { transform: translateY(-1px); box-shadow: 0 6px 16px rgb(79 70 229 / 0.4); }

/* ===================================
   FILE INFO
   =================================== */
.file-info {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  background: #f1f5f9;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  font-size: 0.875rem;
  color: var(--text);
  margin-bottom: 16px;
}
.file-info svg { flex-shrink: 0; }

/* ===================================
   CONTROLS
   =================================== */
.controls { margin-top: 20px; }

.options-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
  margin-bottom: 16px;
}
@media (min-width: 540px) {
  .options-grid { grid-template-columns: 1fr 1fr; }
}

.field { display: flex; flex-direction: column; gap: 6px; }
.field label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text);
}

/* Range slider */
input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  border-radius: 3px;
  background: linear-gradient(
    to right,
    var(--primary) 0%,
    var(--primary) var(--fill, 73.3%),
    var(--border) var(--fill, 73.3%),
    var(--border) 100%
  );
  outline: none;
  cursor: pointer;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--primary);
  box-shadow: 0 0 0 3px rgb(79 70 229 / 0.2);
  cursor: pointer;
  transition: box-shadow 0.15s;
}
input[type="range"]::-webkit-slider-thumb:hover {
  box-shadow: 0 0 0 5px rgb(79 70 229 / 0.2);
}
input[type="range"]::-moz-range-thumb {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--primary);
  border: none;
  cursor: pointer;
}

.range-hints {
  display: flex;
  justify-content: space-between;
  font-size: 0.72rem;
  color: var(--text-muted);
}

select {
  padding: 10px 14px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-family: inherit;
  color: var(--text);
  background: var(--bg);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2.5'%3E%3Cpolyline points='6 9 12 15 18 9'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 36px;
  appearance: none;
  cursor: pointer;
  transition: border-color 0.2s;
}
select:focus { outline: none; border-color: var(--primary); }

/* ===================================
   BUTTONS
   =================================== */
.btn-compress {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 14px 24px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.15s, opacity 0.15s;
  box-shadow: 0 4px 12px rgb(79 70 229 / 0.35);
  margin-bottom: 10px;
}
.btn-compress:hover { transform: translateY(-1px); box-shadow: 0 6px 20px rgb(79 70 229 / 0.45); }
.btn-compress:disabled { opacity: 0.7; cursor: not-allowed; transform: none; }

.btn-reset {
  width: 100%;
  padding: 10px;
  background: none;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  color: var(--text-muted);
  cursor: pointer;
  transition: border-color 0.2s, color 0.2s;
}
.btn-reset:hover { border-color: var(--primary); color: var(--primary); }

.btn-download {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 28px;
  background: var(--success);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.15s;
  box-shadow: 0 4px 12px rgb(16 185 129 / 0.3);
  margin-top: 16px;
}
.btn-download:hover { transform: translateY(-1px); box-shadow: 0 6px 16px rgb(16 185 129 / 0.4); }

/* ===================================
   RESULTS
   =================================== */
.results { margin-top: 24px; }

/* Stats bar */
.stats-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  background: #f0fdf4;
  border: 1px solid #bbf7d0;
  border-radius: var(--radius-sm);
  padding: 16px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}
.stat { text-align: center; }
.stat-label { display: block; font-size: 0.72rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.06em; margin-bottom: 2px; }
.stat-value { display: block; font-size: 1.1rem; font-weight: 700; color: var(--text); }
.stat-value.saving { color: var(--success); font-size: 1.25rem; }
.stat-arrow { color: var(--success); }
.stat-saving { background: rgb(16 185 129 / 0.08); padding: 8px 16px; border-radius: var(--radius-sm); }

/* Image previews */
.preview-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-bottom: 4px;
}
.preview-box {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.preview-label {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.preview-box img {
  width: 100%;
  aspect-ratio: 4/3;
  object-fit: cover;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--bg);
}
.preview-size {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-align: center;
}

/* ===================================
   SIDEBAR
   =================================== */
.sidebar { display: none; }
@media (min-width: 1024px) { .sidebar { display: block; } }

/* ===================================
   CONTENT SECTIONS
   =================================== */
.content-section { margin-bottom: 48px; }
.content-section h2 {
  font-size: 1.375rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text);
  margin-bottom: 20px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--border);
}

.steps-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}
@media (min-width: 640px) { .steps-grid { grid-template-columns: repeat(3, 1fr); } }

.step {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 24px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
}
.step-number {
  width: 40px; height: 40px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff;
  font-size: 1rem;
  font-weight: 800;
  display: flex; align-items: center; justify-content: center;
  margin-bottom: 12px;
}
.step h3 { font-size: 1rem; font-weight: 700; color: var(--text); margin-bottom: 8px; }
.step p { font-size: 0.875rem; color: var(--text-muted); line-height: 1.6; }

.benefits-list { list-style: none; display: flex; flex-direction: column; gap: 14px; }
.benefits-list li {
  display: flex; align-items: flex-start; gap: 12px;
  font-size: 0.9375rem; color: var(--text-muted);
  background: var(--bg-card); padding: 16px;
  border-radius: var(--radius-sm); border: 1px solid var(--border);
}
.benefits-list li svg { flex-shrink: 0; margin-top: 2px; }
.benefits-list li strong { color: var(--text); }

.faq-list { display: flex; flex-direction: column; gap: 10px; }
.faq-list details {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius-sm); overflow: hidden; transition: box-shadow 0.2s;
}
.faq-list details[open] { box-shadow: var(--shadow); }
.faq-list summary {
  padding: 16px 20px; font-size: 0.9375rem; font-weight: 600;
  color: var(--text); cursor: pointer; list-style: none;
  display: flex; justify-content: space-between; align-items: center;
  user-select: none;
}
.faq-list summary::-webkit-details-marker { display: none; }
.faq-list summary::after { content: '+'; font-size: 1.25rem; color: var(--primary); font-weight: 300; transition: transform 0.2s; }
.faq-list details[open] summary::after { transform: rotate(45deg); }
.faq-list details p {
  padding: 14px 20px 16px; font-size: 0.875rem; color: var(--text-muted);
  line-height: 1.7; border-top: 1px solid var(--border);
}
.faq-list details strong { color: var(--text); }

/* ===================================
   FOOTER
   =================================== */
footer {
  background: var(--text); color: rgb(255 255 255 / 0.7);
  padding: 24px 0; text-align: center;
}
.footer-inner { display: flex; flex-direction: column; gap: 6px; }
footer a { color: var(--primary-light); text-decoration: none; }
footer a:hover { text-decoration: underline; }
.footer-disclaimer { font-size: 0.8rem; opacity: 0.6; }

@media (max-width: 639px) {
  .tool-card { padding: 18px; }
  main { padding: 20px 0 40px; }
}