:root{--primary-color:#6366f1;--primary-hover:#4f46e5;--text-color:#1f2937;--background-color:#f9fafb;--card-background:#ffffff;--input-background:#f3f4f6;--border-color:#e5e7eb;--shadow-color:rgba(0,0,0,0.1);--result-background:#f0f9ff;--history-item-bg:#f3f4f6;--history-hover-bg:#e5e7eb}[data-theme=dark]{--primary-color:#818cf8;--primary-hover:#6366f1;--text-color:#e5e7eb;--background-color:#111827;--card-background:#1f2937;--input-background:#374151;--border-color:#4b5563;--shadow-color:rgba(0,0,0,0.5);--result-background:#1e3a8a;--history-item-bg:#374151;--history-hover-bg:#4b5563}*{box-sizing:border-box;margin:0;padding:0;transition:background-color .3s,color .3s,border-color .3s,box-shadow .3s}body{font-family:Inter,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Open Sans,Helvetica Neue,sans-serif;background-color:var(--background-color);color:var(--text-color);line-height:1.6}.weight-converter-container{max-width:600px;margin:2rem auto;padding:0 1rem}.header{display:flex;justify-content:space-between;align-items:center;margin-bottom:2rem}.header h1{font-size:2rem;font-weight:700;background:linear-gradient(135deg,var(--primary-color),#a78bfa);-webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:rgba(0,0,0,0)}.theme-toggle{background:none;border:none;font-size:1.5rem;cursor:pointer;padding:.5rem;border-radius:50%}.theme-toggle:hover{background-color:var(--input-background)}.converter-card{background-color:var(--card-background);border-radius:1rem;padding:2rem;box-shadow:0 10px 25px var(--shadow-color);margin-bottom:2rem;border:1px solid var(--border-color)}.input-group{margin-bottom:1.5rem}.input-group label{display:block;margin-bottom:.5rem;font-weight:500}.input-group .weight-input{width:100%;padding:.75rem 1rem;font-size:1rem;border:1px solid var(--border-color);border-radius:.5rem;background-color:var(--input-background);color:var(--text-color)}.input-group .weight-input:focus{outline:none;border-color:var(--primary-color);box-shadow:0 0 0 3px rgba(99,102,241,.2)}.units-container{display:flex;gap:1rem;margin-bottom:1.5rem;align-items:flex-end}.unit-selector{flex:1}.unit-selector label{display:block;margin-bottom:.5rem;font-weight:500}.unit-selector .unit-select{width:100%;padding:.75rem 1rem;font-size:1rem;border:1px solid var(--border-color);border-radius:.5rem;background-color:var(--input-background);color:var(--text-color)}.unit-selector .unit-select:focus{outline:none;border-color:var(--primary-color);box-shadow:0 0 0 3px rgba(99,102,241,.2)}.swap-button{background-color:var(--input-background);border:1px solid var(--border-color);color:var(--text-color);height:3rem;width:3rem;font-size:1.5rem;border-radius:.5rem;cursor:pointer;display:flex;align-items:center;justify-content:center;transition:all .2s}.swap-button:hover{transform:scale(1.05)}.convert-button,.swap-button:hover{background-color:var(--primary-color);color:#fff}.convert-button{width:100%;padding:.75rem;border:none;border-radius:.5rem;font-size:1rem;font-weight:600;cursor:pointer;transition:background-color .2s;margin-bottom:1.5rem}.convert-button:hover{background-color:var(--primary-hover)}.result{padding:1.5rem;background-color:var(--result-background);border-radius:.5rem;text-align:center}.result h2{font-size:1rem;margin-bottom:.5rem;font-weight:500}.result .result-value{font-size:1.5rem;font-weight:700}.history-section{background-color:var(--card-background);border-radius:1rem;padding:1.5rem;box-shadow:0 4px 15px var(--shadow-color);border:1px solid var(--border-color)}.history-header{display:flex;justify-content:space-between;align-items:center}.history-toggle{cursor:pointer;font-size:1.25rem;font-weight:600;display:flex;align-items:center;user-select:none}.history-toggle:hover{color:var(--primary-color)}.clear-history{background:none;border:none;color:#ef4444;font-size:.875rem;cursor:pointer}.clear-history:hover{text-decoration:underline}.history-list{margin-top:1rem;max-height:300px;overflow-y:auto;border-radius:.5rem;border:1px solid var(--border-color)}.history-item{padding:.75rem 1rem;display:flex;justify-content:space-between;align-items:center;background-color:var(--history-item-bg);border-bottom:1px solid var(--border-color);transition:background-color .2s}.history-item:last-child{border-bottom:none}.history-item:hover{background-color:var(--history-hover-bg)}.history-item .arrow{color:var(--primary-color);margin:0 .5rem}.empty-history{text-align:center;padding:1.5rem;color:#9ca3af;font-style:italic}footer{margin-top:2rem;text-align:center;font-size:.875rem;color:#6b7280}@keyframes fadeIn{0%{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}.history-item,.result{animation:fadeIn .3s ease-out}@media(max-width:640px){.weight-converter-container{margin:1rem auto}.converter-card,.history-section{padding:1.25rem}.units-container{flex-direction:column;gap:1rem}.swap-button{align-self:center;transform:rotate(90deg);margin:.5rem 0}.swap-button:hover{transform:rotate(90deg) scale(1.05)}}