*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
body{font-family:Arial,"PingFang SC","Microsoft YaHei",sans-serif;background:#f3f4f6;color:#111827;min-height:100vh}
a{color:inherit;text-decoration:none}
button{font-family:inherit;cursor:pointer}

/* hero */
.hero{background:#fff;border-bottom:1px solid #e5e7eb}
.hero-inner{max-width:1280px;margin:0 auto;padding:32px 16px;text-align:center}
.hero h1{font-size:clamp(24px,4vw,36px);font-weight:700;color:#111827;margin-bottom:10px}
.hero p{color:#6b7280;font-size:15px}

/* tool box */
.tool-wrap{max-width:1280px;margin:0 auto;padding:24px 16px}
.tool-box{background:#f5f7fb;border-radius:0;padding:16px;color:#111827}
.selector-page{background:#fff;border:1px solid #e5e7eb;border-radius:12px;padding:16px}

.info-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:16px;margin-bottom:16px}
.panel{border:1px solid #e5e7eb;background:#f8fafc;border-radius:12px;padding:16px;display:flex;flex-direction:column;min-height:200px}
.panel-title{font-size:15px;font-weight:700;color:#1e293b;margin-bottom:12px;display:flex;align-items:center;gap:8px}
.panel-title .icon{color:#3b82f6;font-size:16px}
.tips-list{display:flex;flex-direction:column;gap:8px;flex:1}
.tip-item{font-size:12px;color:#475569;line-height:1.6;padding-left:14px;position:relative}
.tip-item::before{content:"•";color:#3b82f6;font-weight:bold;position:absolute;left:0;top:0}
kbd{display:inline-block;padding:1px 5px;font-size:11px;font-family:Consolas,Monaco,monospace;color:#374151;background:#f3f4f6;border:1px solid #d1d5db;border-radius:3px;box-shadow:inset 0 -1px 0 #d1d5db}
.tips-action{margin-top:16px}
.start-btn{display:flex;align-items:center;justify-content:center;width:100%;height:44px;background:linear-gradient(90deg,#2563eb,#1d4ed8);color:#fff;border:0;border-radius:8px;font-size:15px;font-weight:700;cursor:pointer;box-shadow:0 4px 14px rgba(37,99,235,.2);transition:all .2s}
.start-btn:hover{background:linear-gradient(90deg,#1d4ed8,#1e40af);transform:translateY(-1px);box-shadow:0 6px 20px rgba(37,99,235,.3)}
.tips-desc{font-size:12px;color:#64748b;text-align:center;margin-top:8px}

.device-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:10px}
.device-item{background:#fff;border:1px solid #e2e8f0;border-radius:8px;padding:10px 12px}
.device-item span{font-size:12px;color:#64748b;display:block;margin-bottom:2px}
.device-item strong{font-size:15px;color:#0f172a;font-weight:600}

/* groups */
.group-list{display:grid;grid-template-columns:repeat(2,1fr);gap:14px;margin-top:4px}
.group-card{border:1px solid #e5e7eb;border-radius:10px;padding:14px;background:#fafafa}
.group-card-full{grid-column:span 2}
.group-head{margin-bottom:10px}
.group-title{font-size:15px;font-weight:700;color:#1e293b;display:flex;align-items:center;gap:6px;margin-bottom:4px}
.group-title .icon{color:#3b82f6}
.group-desc{font-size:12px;color:#6b7280}
.group-items{display:grid;gap:8px}
.grid-3{grid-template-columns:repeat(3,1fr)}
.grid-6{grid-template-columns:repeat(6,1fr)}
.grid-2{grid-template-columns:repeat(2,1fr)}
.group-item{display:flex;align-items:center;gap:7px;border:1px solid #d1d5db;background:#fff;color:#111827;border-radius:8px;padding:7px 9px;cursor:pointer;font-size:13px;transition:all .15s;text-align:left}
.group-item:hover{border-color:#60a5fa;background:#eff6ff}
.item-preview{width:22px;height:22px;border-radius:4px;border:1px solid rgba(0,0,0,.15);flex-shrink:0}
.item-text{white-space:nowrap;overflow:hidden;text-overflow:ellipsis}

/* test stage */
.test-stage{position:fixed;left:0;top:0;width:100vw;height:100vh;z-index:99999;display:none;overflow:hidden;user-select:none;-webkit-user-select:none;cursor:none}
.stage-bottom,.stage-bottom *{cursor:default}
.test-stage.active{display:block}
.stage-canvas{position:absolute;left:0;top:0;width:100%;height:100%;z-index:3}
.stage-overlay{position:absolute;left:0;top:0;width:100%;height:100%;z-index:2}
/* bottom bar */
.stage-bottom{position:absolute;left:0;right:0;bottom:0;z-index:8;color:#fff;background:rgba(0,0,0,.72);border-top:1px solid rgba(255,255,255,.2);padding:10px 14px;min-height:70px;display:flex;align-items:center;justify-content:space-between;gap:12px;transform:translateY(100%);transition:transform .2s ease;backdrop-filter:blur(10px)}
.stage-bottom.visible{transform:translateY(0)}
.stage-bottom-trigger{position:absolute;left:0;right:0;bottom:0;height:22px;z-index:9}
.stage-bottom-left{min-width:0}
.stage-bottom-right{display:flex;align-items:center;gap:6px;flex-shrink:0}
.stage-title{font-size:14px;font-weight:700;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.stage-desc{font-size:12px;opacity:.9}
.btn{border:1px solid rgba(255,255,255,.28);background:rgba(255,255,255,.14);color:#fff;border-radius:999px;padding:7px 12px;cursor:pointer;font-size:13px;font-weight:600;transition:all .2s}
.btn:hover{transform:translateY(-1px);border-color:rgba(255,255,255,.55);background:rgba(255,255,255,.22)}
.btn-prev{background:rgba(59,130,246,.26);border-color:rgba(59,130,246,.52)}
.btn-next{background:rgba(16,185,129,.26);border-color:rgba(16,185,129,.52)}
.btn-exit{background:rgba(239,68,68,.26);border-color:rgba(239,68,68,.52)}
.progress-pill{display:inline-flex;align-items:center;justify-content:center;min-width:52px;height:28px;padding:0 10px;border-radius:999px;font-size:12px;font-weight:700;color:#e5e7eb;background:rgba(255,255,255,.14);border:1px solid rgba(255,255,255,.22)}

/* canvas overlay helpers */

/* gamma */

/* contrast overlay */
.contrast-overlay{z-index:6;padding:0;box-sizing:border-box;display:flex;flex-direction:column;overflow:hidden;height:100%}
.contrast-row{display:grid;grid-template-columns:repeat(15,1fr);flex:1}
.contrast-cell{display:flex;align-items:center;justify-content:center;font-size:11px;font-weight:600}
.contrast-cell.dark{color:rgba(255,255,255,.7)}
.contrast-cell.bright{color:rgba(0,0,0,.5)}

/* flash square */
.flash-square{width:200px;height:200px;border:3px solid #fff;animation:flashAnim .7s steps(1) infinite}
@keyframes flashAnim{0%{background:#000}50%{background:#fff}100%{background:#000}}
.center-flex{display:flex;align-items:center;justify-content:center}

/* features section */
.section{max-width:1280px;margin:0 auto;padding:40px 16px}
.section-title{text-align:center;margin-bottom:32px}
.section-title h2{font-size:clamp(22px,3vw,30px);font-weight:700;color:#111827}
.section-title p{color:#6b7280;margin-top:8px;font-size:14px}
.features-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.feature-card{background:#fff;border-radius:10px;box-shadow:0 2px 8px rgba(0,0,0,.06);padding:24px;text-align:center;transition:box-shadow .2s}
.feature-card:hover{box-shadow:0 6px 20px rgba(0,0,0,.1)}
.feature-icon{width:56px;height:56px;border-radius:50%;display:flex;align-items:center;justify-content:center;margin:0 auto 16px}
.feature-icon svg{width:28px;height:28px}
.feature-card h3{font-size:17px;font-weight:600;margin-bottom:8px}
.feature-card p{font-size:13px;color:#6b7280;line-height:1.6}

/* use cases */
.cases-section{background:#f9fafb;padding:40px 0}
.cases-inner{max-width:1280px;margin:0 auto;padding:0 16px}
.cases-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:20px}
.case-card{background:#fff;border-radius:12px;box-shadow:0 4px 12px rgba(0,0,0,.07);overflow:hidden;display:flex;transition:transform .2s,box-shadow .2s}
.case-card:hover{transform:scale(1.02);box-shadow:0 8px 24px rgba(0,0,0,.12)}
.case-icon{flex-shrink:0;width:160px;display:flex;align-items:center;justify-content:center;padding:24px}
.case-icon svg{width:64px;height:64px}
.case-body{padding:20px;display:flex;flex-direction:column;justify-content:center}
.case-body h3{font-size:16px;font-weight:600;color:#1f2937;margin-bottom:8px;display:flex;align-items:center;gap:8px}
.badge{font-size:11px;padding:2px 8px;border-radius:999px;font-weight:600}
.badge-blue{background:#dbeafe;color:#1d4ed8}
.badge-amber{background:#fef3c7;color:#92400e}
.case-body p{font-size:13px;color:#6b7280;line-height:1.6}

/* faq */
.faq-section{background:#f9fafb;padding:40px 0}
.faq-inner{max-width:896px;margin:0 auto;padding:0 16px}
.faq-item{background:#fff;border-radius:12px;box-shadow:0 2px 8px rgba(0,0,0,.06);padding:20px 24px;display:flex;gap:16px;transition:box-shadow .2s}
.faq-item:hover{box-shadow:0 4px 16px rgba(0,0,0,.1)}
.faq-icon{flex-shrink:0;width:40px;height:40px;border-radius:50%;background:#dbeafe;display:flex;align-items:center;justify-content:center}
.faq-icon svg{width:22px;height:22px;color:#2563eb}
.faq-item h3{font-size:15px;font-weight:600;color:#1f2937;margin-bottom:6px}
.faq-item p{font-size:13px;color:#4b5563;line-height:1.7}
.space-y>*+*{margin-top:14px}

/* footer */
footer{background:#fff;border-top:1px solid #e5e7eb;padding:28px 16px;text-align:center;font-size:13px;color:#6b7280}

/* responsive */
@media(max-width:1100px){
  .info-grid{grid-template-columns:1fr}
  .panel{min-height:auto}
  .group-list{grid-template-columns:1fr}
  .group-card-full{grid-column:span 1}
  .grid-3,.grid-6,.grid-2{grid-template-columns:repeat(2,1fr)}
  .features-grid{grid-template-columns:1fr}
  .cases-grid{grid-template-columns:1fr}
  .stage-bottom{flex-direction:column;align-items:flex-start}
}
@media(max-width:768px){
  .case-icon{width:100px}
}