:root { color-scheme: light dark; }
* { box-sizing: border-box; }
body { margin: 0; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", "PingFang SC", "Microsoft YaHei", sans-serif; }
.container { max-width: 720px; margin: 0 auto; padding: 16px; }
h1 { font-size: 22px; margin: 12px 0 16px; }
form { background: rgba(0,0,0,0.03); padding: 12px; border-radius: 8px; }
.field { margin-bottom: 12px; display: flex; flex-direction: column; gap: 6px; }
label { font-size: 14px; }
input[type="file"], input[type="number"] { padding: 10px; border: 1px solid rgba(0,0,0,0.15); border-radius: 6px; font-size: 16px; }
button { width: 100%; padding: 12px; font-size: 16px; border: none; border-radius: 8px; background: #2f80ed; color: #fff; }
button:disabled { opacity: 0.6; }
.grid { display: grid; grid-template-columns: 1fr; gap: 12px; }
@media (min-width: 640px) { .grid { grid-template-columns: repeat(2, 1fr); } }
.status { margin: 12px 0; min-height: 24px; font-size: 14px; }
.progress { position: relative; width: 100%; height: 12px; background: rgba(0,0,0,0.1); border-radius: 6px; overflow: hidden; margin: 8px 0 12px; }
.progress .bar { height: 100%; background: #27ae60; width: 0%; transition: width 0.2s ease; }
.progress .progress-text { position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); font-size: 12px; color: #000; }
.result { margin-top: 12px; }
.actions { display: flex; align-items: center; gap: 12px; margin-bottom: 8px; }
#download { display: inline-block; padding: 8px 12px; background: #27ae60; color: #fff; border-radius: 6px; text-decoration: none; }
#preview { width: 100%; height: auto; border-radius: 8px; border: 1px solid rgba(0,0,0,0.1); }
.hidden { display: none; }
.note { font-size: 12px; color: rgba(0,0,0,0.7); margin-top: 6px; }
.file-input-hidden { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0; }
.file-actions { display: flex; gap: 10px; }
.btn { display: inline-block; padding: 10px 14px; font-size: 15px; border-radius: 8px; border: none; cursor: pointer; }
.btn-primary { background: linear-gradient(135deg, #2f80ed, #56ccf2); color: #fff; }
.btn-danger { background: #eb5757; color: #fff; }
.btn:disabled { opacity: 0.6; cursor: not-allowed; }
.video-preview { width: 100%; max-height: 320px; border-radius: 8px; border: 1px solid rgba(0,0,0,0.1); background: #000; }