.win7-calc{width:540px;margin:20px auto;font-family:Tahoma,Segoe UI,Arial;direction:ltr;background:#dcdcdc;border:1px solid #9a9a9a;border-radius:6px;padding:12px;box-shadow:2px 2px 8px rgba(0,0,0,0.2)}
.win7-calc .display-row{display:flex;justify-content:space-between;align-items:center;margin-bottom:8px}
.win7-calc .title{font-weight:bold;color:#222}
.win7-calc .format-switch select{margin-left:8px}
.win7-calc .screen{display:flex;align-items:center;margin-bottom:6px}
.win7-calc input#calc-input{flex:1;padding:10px;font-size:16px;border:1px solid #888;border-radius:3px;text-align:right}
.win7-calc #history-toggle{margin-left:8px;padding:6px 8px;border-radius:3px;background:#eee;border:1px solid #aaa;cursor:pointer}
.history-panel{display:none;background:#fff;border:1px solid #bbb;padding:8px;margin-top:8px;border-radius:4px;max-height:220px;overflow:auto}
.hist-list{list-style:none;padding:0;margin:0}
.hist-list li{padding:6px;border-bottom:1px solid #eee;cursor:pointer;display:flex;justify-content:space-between}
.hist-list li:hover{background:#f0f0f0}
.btn-grid{display:grid;grid-template-columns:repeat(5,1fr);gap:6px;margin-top:10px}
.btn{padding:10px;font-size:14px;border-radius:4px;border:1px solid #999;background:linear-gradient(#fff,#ddd);cursor:pointer;box-shadow:inset 0 -2px 0 rgba(0,0,0,0.07)}
.btn:active{box-shadow:inset 0 2px 0 rgba(0,0,0,0.08)}
.btn.fn{background:linear-gradient(#f3f3f3,#dcdcdc)}
.btn.op{background:linear-gradient(#ffe,#ffd,#ffc)}
.btn.eq{background:linear-gradient(#4e8ef7,#2b6fe6);color:#fff;font-weight:bold}
.btn.clear{background:linear-gradient(#f7d3d3,#f2bcbc)}
.result{margin-top:8px;background:#e9f2ff;padding:8px;border:1px solid #bcd;min-height:36px;border-radius:3px;white-space:pre-wrap;overflow:auto}
.status{margin-top:8px;font-size:12px;color:#333}