:root{--primary-color: #4f46e5;--primary-hover: #4338ca;--secondary-color: #10b981;--bg-color: #f3f4f6;--text-color: #1f2937;--calculator-bg: rgba(255, 255, 255, .8);--display-bg: rgba(0, 0, 0, .75);--display-text: #ffffff;--btn-bg: rgba(255, 255, 255, .9);--btn-hover: #e5e7eb;--btn-operator-bg: #f9fafb;--btn-operator-text: #4f46e5;--btn-equal-bg: #4f46e5;--btn-equal-text: #ffffff;--shadow: 0 10px 15px -3px rgba(0, 0, 0, .1), 0 4px 6px -2px rgba(0, 0, 0, .05)}*{box-sizing:border-box;margin:0;padding:0;font-family:Inter,sans-serif}body{background:linear-gradient(135deg,#667eea,#764ba2);min-height:100vh;display:flex;flex-direction:column;align-items:center;padding:2rem;color:var(--text-color)}header{text-align:center;margin-bottom:2rem;color:#fff;text-shadow:0 2px 4px rgba(0,0,0,.2)}h1{font-size:2.5rem;margin-bottom:.5rem}.subtitle{font-size:1.1rem;opacity:.9}.main-container{display:flex;gap:2rem;align-items:flex-start;flex-wrap:wrap;justify-content:center;width:100%;max-width:1200px}.calculator-grid{display:grid;justify-content:center;align-content:center;grid-template-columns:repeat(4,80px);grid-template-rows:minmax(100px,auto) repeat(6,80px);gap:10px;background:var(--calculator-bg);padding:20px;border-radius:20px;box-shadow:0 20px 50px #00000026;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border:1px solid rgba(255,255,255,.3)}.calculator-grid.scientific{grid-template-columns:repeat(5,80px)}.output{grid-column:1 / -1;background-color:var(--display-bg);display:flex;align-items:flex-end;justify-content:space-around;flex-direction:column;padding:20px;word-wrap:break-word;word-break:break-all;border-radius:10px;margin-bottom:10px;box-shadow:inset 0 2px 5px #00000080}.output .previous-operand{color:#ffffffbf;font-size:1.2rem}.output .current-operand{color:var(--display-text);font-size:2.5rem;font-weight:700}button{cursor:pointer;font-size:1.5rem;border:1px solid rgba(255,255,255,.5);outline:none;background-color:var(--btn-bg);border-radius:10px;transition:all .2s ease;color:var(--text-color);font-weight:500}button:hover{background-color:var(--btn-hover);transform:translateY(-2px);box-shadow:0 5px 15px #0000001a}button:active{transform:translateY(0)}button.span-two{grid-column:span 2}button.operator{color:var(--btn-operator-text);background-color:var(--btn-operator-bg);font-weight:700}button.equal{background-color:var(--btn-equal-bg);color:var(--btn-equal-text);grid-column:span 2}button.equal:hover{background-color:var(--primary-hover)}button.scientific-btn{font-size:1.1rem;background-color:#ffffffb3}.history-container{background:var(--calculator-bg);padding:20px;border-radius:20px;width:300px;max-height:600px;overflow-y:auto;box-shadow:0 20px 50px #00000026;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border:1px solid rgba(255,255,255,.3)}.history-container h2{margin-bottom:1rem;font-size:1.5rem;border-bottom:2px solid rgba(0,0,0,.1);padding-bottom:.5rem}.history-list{list-style:none}.history-item{padding:10px;border-bottom:1px solid rgba(0,0,0,.05);cursor:pointer;transition:background .2s}.history-item:hover{background:#0000000d}.history-item .expression{display:block;font-size:.9rem;color:#666}.history-item .result{display:block;font-size:1.1rem;font-weight:700;color:var(--primary-color)}.clear-history{width:100%;margin-top:1rem;padding:.5rem;font-size:1rem;background:#ef4444;color:#fff;border:none}.clear-history:hover{background:#dc2626}footer{margin-top:3rem;text-align:center;color:#fff}.seo-links{display:flex;flex-wrap:wrap;justify-content:center;gap:1rem;margin-top:1rem}.seo-links a{color:#fffc;text-decoration:none;font-size:.9rem;padding:5px 10px;border:1px solid rgba(255,255,255,.3);border-radius:20px;transition:all .2s}.seo-links a:hover{background:#fff3;color:#fff}@media(max-width:800px){.main-container{flex-direction:column;align-items:center}.history-container{width:100%;max-width:400px}.calculator-grid{grid-template-columns:repeat(4,70px);grid-template-rows:minmax(80px,auto) repeat(6,70px)}.calculator-grid.scientific{grid-template-columns:repeat(4,70px);grid-template-columns:repeat(5,60px);grid-template-rows:minmax(80px,auto) repeat(6,60px)}button{font-size:1.2rem}}