:root{--bg:#0d1117;--card:#161b22;--accent:#00d084;--accent-hover:#00b371;--text:#e6edf3;--muted:#8b949e;--border:#30363d}
*{box-sizing:border-box}
body{background:var(--bg);color:var(--text);font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Oxygen,Ubuntu,sans-serif;margin:0;padding-top:56px}
a{color:var(--accent);text-decoration:none}
a:hover{color:var(--accent-hover)}

/* Navbar */
#mainNav{background:rgba(13,17,23,.95);backdrop-filter:blur(10px);border-bottom:1px solid var(--border)}

/* Buttons */
.btn-accent{background:var(--accent);color:#0d1117;font-weight:600;border:none;border-radius:8px;padding:12px 32px;transition:all .2s}
.btn-accent:hover,.btn-accent:focus{background:var(--accent-hover);color:#0d1117;transform:translateY(-1px);box-shadow:0 4px 20px rgba(0,208,132,.3)}
.btn-accent:disabled{opacity:.5;transform:none;box-shadow:none}
.btn-outline-accent{color:var(--accent);border:2px solid var(--accent);background:transparent;border-radius:8px;padding:10px 28px;font-weight:600;transition:all .2s}
.btn-outline-accent:hover{background:var(--accent);color:#0d1117}
.bg-accent{background:var(--accent)!important;color:#0d1117!important;font-weight:600}

/* Hero */
.hero-section{padding:100px 0 80px;background:linear-gradient(180deg,#0d1117 0%,#0a1628 50%,#0d1117 100%);text-align:center}
.hero-title{font-size:clamp(2rem,5vw,3.5rem);font-weight:800;margin-bottom:16px;background:linear-gradient(135deg,#fff 0%,var(--accent) 100%);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.hero-subtitle{font-size:clamp(1.1rem,3vw,1.5rem);color:var(--accent);font-weight:600;margin-bottom:12px}
.hero-desc{color:var(--muted);font-size:1.1rem;max-width:600px;margin:0 auto}

/* Section titles */
.section-title{font-size:1.8rem;font-weight:700;color:var(--text)}
.section-title::after{content:'';display:block;width:60px;height:3px;background:var(--accent);margin:12px auto 0;border-radius:2px}

/* Drop Zone */
.drop-zone{border:2px dashed var(--border);border-radius:16px;padding:60px 20px;text-align:center;cursor:pointer;transition:all .3s;background:var(--card);max-width:700px;margin:0 auto}
.drop-zone:hover,.drop-zone.drag-over{border-color:var(--accent);background:rgba(0,208,132,.05)}
.drop-zone.drag-over{transform:scale(1.01)}
.drop-icon{width:48px;height:48px;margin-bottom:16px}
.drop-text{font-size:1.2rem;font-weight:600;margin-bottom:4px}
.drop-subtext{color:var(--muted);margin-bottom:8px}
.drop-formats{color:var(--muted);font-size:.85rem}

/* Quality */
.quality-control{max-width:600px;margin:0 auto;text-align:center}
.accent-range::-webkit-slider-thumb{background:var(--accent)}
.accent-range::-moz-range-thumb{background:var(--accent)}
.accent-range::-webkit-slider-runnable-track{background:var(--border)}
.accent-range::-moz-range-track{background:var(--border)}

/* File List */
.file-item{background:var(--card);border:1px solid var(--border);border-radius:10px;padding:12px 16px;margin-bottom:8px;display:flex;align-items:center;justify-content:space-between;gap:12px}
.file-item .file-name{font-weight:500;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;flex:1;min-width:0}
.file-item .file-size{color:var(--muted);font-size:.85rem;white-space:nowrap}
.file-item .file-remove{background:none;border:none;color:#f85149;cursor:pointer;font-size:1.2rem;padding:4px 8px;border-radius:4px;transition:background .2s}
.file-item .file-remove:hover{background:rgba(248,81,73,.15)}

/* Results */
.result-card{background:var(--card);border:1px solid var(--border);border-radius:12px;overflow:hidden;transition:transform .2s}
.result-card:hover{transform:translateY(-2px)}
.result-preview{width:100%;height:180px;object-fit:cover;background:#21262d}
.result-body{padding:16px}
.result-name{font-weight:600;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;margin-bottom:8px}
.result-stats{display:flex;justify-content:space-between;margin-bottom:12px;font-size:.9rem}
.result-original{color:var(--muted)}
.result-webp{color:var(--accent);font-weight:600}
.result-savings{text-align:center;margin-bottom:12px}
.savings-badge{display:inline-block;padding:4px 12px;border-radius:20px;font-weight:600;font-size:.85rem}
.savings-good{background:rgba(0,208,132,.15);color:var(--accent)}
.savings-great{background:rgba(0,208,132,.25);color:var(--accent)}
.savings-negative{background:rgba(248,81,73,.15);color:#f85149}
.result-download{width:100%}

/* Steps */
.step-card{background:var(--card);border:1px solid var(--border);border-radius:12px;padding:32px 24px;height:100%}
.step-number{width:48px;height:48px;background:var(--accent);color:#0d1117;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:1.3rem;font-weight:800;margin:0 auto 16px}
.step-card h3{font-size:1.2rem;font-weight:600;margin-bottom:8px}
.step-card p{color:var(--muted);font-size:.95rem;margin:0}

/* Features */
.feature-card{background:var(--card);border:1px solid var(--border);border-radius:12px;padding:28px 20px;text-align:center;height:100%;transition:border-color .2s}
.feature-card:hover{border-color:var(--accent)}
.feature-icon{font-size:2.5rem;margin-bottom:12px}
.feature-card h3{font-size:1.1rem;font-weight:600;margin-bottom:8px}
.feature-card p{color:var(--muted);font-size:.9rem;margin:0}

/* Accordion / FAQ */
.accordion-item{background:var(--card);border:1px solid var(--border)!important;margin-bottom:8px;border-radius:10px!important;overflow:hidden}
.accordion-button{background:var(--card);color:var(--text);font-weight:600;box-shadow:none!important}
.accordion-button:not(.collapsed){background:rgba(0,208,132,.08);color:var(--accent)}
.accordion-button::after{filter:invert(1) brightness(2)}
.accordion-body{color:var(--muted);background:var(--card)}

/* Footer */
footer{border-top:1px solid var(--border);background:var(--card)}
.footer-link{color:var(--muted);transition:color .2s}
.footer-link:hover{color:var(--accent)}

/* Progress */
.progress-bar-accent{background:var(--accent)}

/* Spinner overlay */
.converting-overlay{position:fixed;top:0;left:0;right:0;bottom:0;background:rgba(13,17,23,.85);display:flex;align-items:center;justify-content:center;z-index:9999;flex-direction:column;gap:16px}
.converting-overlay .spinner-border{width:3rem;height:3rem;color:var(--accent)}

/* Toast */
.toast-error{position:fixed;top:80px;right:20px;background:#f85149;color:#fff;padding:12px 24px;border-radius:8px;z-index:10000;font-weight:500;box-shadow:0 4px 20px rgba(0,0,0,.4);animation:slideIn .3s ease}
@keyframes slideIn{from{transform:translateX(100px);opacity:0}to{transform:translateX(0);opacity:1}}

/* Responsive */
@media(max-width:768px){.hero-section{padding:60px 0 50px}.drop-zone{padding:40px 16px}.result-preview{height:140px}}
@media(max-width:480px){.hero-section{padding:40px 0 30px}.file-item{flex-wrap:wrap}.file-item .file-size{order:3;width:100%;text-align:right}}