/* Aug 21 controlled visual + navigation pass */
:root{--tdc-ink:#0b1020;--tdc-green:#4caf5a;--tdc-green-dark:#33892f;--tdc-soft:#f5f8f6;--tdc-line:#dbe4de;--tdc-blue:#4c7ee8;--tdc-gold:#e8b630;--tdc-red:#d84b3e}
html{scroll-behavior:smooth}body{color:var(--tdc-ink)!important;background:#fff}body *:not(.ad-slot):not(.ad-slot *):not(.ad-placeholder):not(.ad-placeholder *){--muted:var(--tdc-ink)}
p,li,label,small,summary,legend,td,th,.helper,.source-note,.field-help,.card-copy,.description{color:var(--tdc-ink)!important}
.site-header{background:rgba(255,255,255,.97);border-bottom:1px solid #e7ece9;position:sticky;top:0;z-index:1000;backdrop-filter:blur(10px)}
.tdc-nav-row{min-height:82px;display:flex;align-items:center;justify-content:space-between;gap:24px}.tdc-wordmark{text-decoration:none;font-size:1.15rem;font-weight:800;white-space:nowrap}.tdc-the{color:#a2a9b5}.tdc-digital{color:var(--tdc-green)}.tdc-calculator-word{color:var(--tdc-ink)}
.tdc-desktop-nav{display:flex;align-items:center;gap:16px}.tdc-desktop-nav>a,.tdc-mobile-nav>a{color:var(--tdc-ink);text-decoration:none;font-weight:700}.tdc-desktop-nav>a:hover{text-decoration:underline;text-underline-offset:5px}
.tdc-header-search{width:min(310px,24vw);position:relative}.tdc-search-input{width:100%;height:44px;border:1px solid #cfd9d3;border-radius:14px;background:#fff;padding:0 16px 0 42px;color:var(--tdc-ink);font-weight:600;outline:none}.tdc-search-input:focus{border-color:var(--tdc-green);box-shadow:0 0 0 3px rgba(76,175,90,.12)}.tdc-search-icon{position:absolute;z-index:2;left:6px;top:5px;border:0;background:transparent;width:34px;height:34px;font-size:1.3rem;color:var(--tdc-ink);cursor:pointer}
.tdc-search-results{display:none;position:absolute;left:0;right:0;top:52px;background:#fff;border:1px solid #d9e2dc;border-radius:16px;box-shadow:0 18px 50px rgba(11,16,32,.14);padding:8px;max-height:430px;overflow:auto;z-index:1200}.tdc-search-results.open{display:block}.tdc-search-result{display:block;padding:11px 12px;border-radius:11px;text-decoration:none}.tdc-search-result:hover,.tdc-search-result:focus{background:#f1f8f2}.tdc-search-result strong{display:block;color:var(--tdc-ink);font-size:.95rem}.tdc-search-result span{display:block;color:var(--tdc-ink);font-size:.78rem;margin-top:2px}.tdc-search-empty{padding:16px;font-weight:700}
.tdc-category-nav{position:relative}.tdc-category-button,.tdc-mobile-search{border:1px solid #d5ded8;background:#fff;color:var(--tdc-ink);font-weight:750;border-radius:13px;padding:11px 15px;white-space:nowrap;cursor:pointer}.tdc-category-menu{display:none;position:absolute;right:0;top:52px;width:360px;background:#fff;border:1px solid #d9e2dc;border-radius:18px;box-shadow:0 18px 50px rgba(11,16,32,.14);padding:10px;z-index:1200;grid-template-columns:1fr 1fr;gap:6px}.tdc-category-nav.open .tdc-category-menu{display:grid}.tdc-category-menu a{padding:12px;border-radius:12px;text-decoration:none;color:var(--tdc-ink)}.tdc-category-menu a:hover{background:#f1f8f2}.tdc-category-menu strong,.tdc-category-menu span{display:block;color:var(--tdc-ink)}.tdc-category-menu span{font-size:.78rem;margin-top:2px}
.tdc-mobile-nav{display:none;align-items:center;gap:8px}.tdc-search-sheet{display:none;position:fixed;inset:0;background:rgba(11,16,32,.36);z-index:1600;padding:84px 16px 16px}.tdc-search-sheet.open{display:block}.tdc-search-sheet-inner{max-width:620px;margin:auto;background:#fff;border-radius:22px;padding:18px;box-shadow:0 30px 80px rgba(11,16,32,.25)}.tdc-search-sheet-top{display:flex;align-items:center;justify-content:space-between;margin-bottom:14px}.tdc-search-sheet-top strong{font-size:1.2rem}.tdc-search-close{border:0;background:#f1f4f2;width:40px;height:40px;border-radius:12px;font-size:1.6rem;cursor:pointer}.tdc-search-input-mobile{height:52px;padding-left:16px}.tdc-search-results-mobile{display:block;position:static;box-shadow:none;border:0;padding:8px 0 0;max-height:60vh}
/* homepage */
.tdc-home-main{max-width:1180px;margin:0 auto;padding:52px 20px 72px}.tdc-home-intro{margin-bottom:30px}.tdc-home-intro .tdc-free-title{margin:0;color:var(--tdc-ink);font-size:clamp(2.6rem,6vw,5.6rem);line-height:.98;font-weight:850;letter-spacing:-.045em}.tdc-home-intro h2{font-size:clamp(1.8rem,3.4vw,3rem);margin:18px 0 8px;font-weight:820}.tdc-home-intro p{font-size:1.05rem;line-height:1.6;margin:0;max-width:820px}.tdc-no-login{display:inline-flex;gap:8px;align-items:center;margin-top:16px;background:#eff8f1;border:1px solid #d6ead9;border-radius:999px;padding:9px 13px;font-size:.9rem;font-weight:800;color:#2f8338!important}.tdc-home-search{position:relative;max-width:720px;margin-top:24px}.tdc-home-search input{width:100%;height:58px;border:1px solid #cdd8d1;border-radius:16px;padding:0 18px;font-size:1rem;color:var(--tdc-ink);font-weight:650}.tdc-home-search .tdc-search-results{top:66px}
.tdc-home-ad{margin:32px 0 38px}.tdc-calculator-directory{max-width:none!important;margin:0!important;padding:0!important}.tdc-calculator-directory>.section-kicker,.tdc-calculator-directory>h2,.tdc-calculator-directory>p{display:none}.tdc-category-section{scroll-margin-top:110px;margin:36px 0 52px}.tdc-category-section h2{font-size:clamp(1.8rem,3vw,2.5rem)!important}.tdc-category-grid{gap:16px}.tdc-calc-card{border:1px solid #d8e2dc!important;border-radius:22px!important;min-height:132px!important}.tdc-calc-card h3{font-size:1.15rem!important}.tdc-calc-card p{color:var(--tdc-ink)!important}
/* standardized education / methodology sections */
.tdc-info-suite{max-width:1180px;margin:42px auto 72px;padding:0 20px}.tdc-info-suite h2{font-size:clamp(1.7rem,3vw,2.25rem);font-weight:850;margin:0 0 16px}.tdc-info-suite h3{font-size:1.05rem;font-weight:800;margin:0 0 8px}.tdc-info-suite p{line-height:1.65;margin:0}.tdc-guidance{background:#fff;border:1px solid #d9e3dd;border-radius:22px;padding:22px;margin-bottom:34px}.tdc-guidance-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.tdc-guidance-card{border:1px solid #e0e7e3;border-radius:16px;padding:17px;background:#fff}.tdc-related{margin:0 0 40px}.tdc-related-kicker{color:var(--tdc-green)!important;font-size:.87rem;font-weight:850;letter-spacing:.09em;margin-bottom:7px}.tdc-related-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}.tdc-related-grid a{display:block;border:1px solid #dde5e0;border-radius:14px;padding:15px 16px;color:var(--tdc-ink);font-weight:800;text-decoration:none;background:#fff}.tdc-related-grid a:hover{border-color:var(--tdc-green);background:#f3faf4}.tdc-understand-grid{display:grid;grid-template-columns:1fr 1fr;gap:16px}.tdc-understand-card{border:1px solid #dce5df;border-radius:18px;padding:20px}.tdc-method{margin-top:16px;background:#f3faf4;border-left:5px solid var(--tdc-green);padding:20px;border-radius:0 16px 16px 0}.tdc-example{margin-top:16px;border:1px solid #dce5df;border-radius:18px;padding:20px}.tdc-info-foot{margin-top:18px;font-size:.88rem}.tdc-info-foot a{color:var(--tdc-ink);font-weight:800}
/* premium math solver */
.tdc-math-shell{display:grid;grid-template-columns:minmax(0,1.25fr) minmax(320px,.75fr);gap:18px;align-items:start}.tdc-math-panel{border:1px solid #dbe4de;border-radius:24px;background:#fff;padding:20px}.tdc-math-display{border:1px solid #cfdad3;border-radius:18px;background:#fbfdfc;padding:14px;margin:14px 0}.tdc-math-display label{display:block;font-size:.82rem;font-weight:800;margin-bottom:7px}.tdc-math-entry{width:100%;min-height:92px;border:0!important;background:transparent!important;padding:0!important;font-size:1.45rem!important;font-weight:700;line-height:1.45;color:var(--tdc-ink);outline:none;resize:vertical}.tdc-keypad-groups{display:grid;gap:10px}.tdc-keypad-row{display:grid;grid-template-columns:repeat(6,minmax(0,1fr));gap:8px}.tdc-key{min-height:50px;border:1px solid #d8e1dc;background:#fff;border-radius:13px;color:var(--tdc-ink);font-weight:800;font-size:1rem;cursor:pointer}.tdc-key:hover{border-color:var(--tdc-green);background:#f3faf4}.tdc-key.function{background:#f5f7fb}.tdc-key.operator{background:#eff8f1;color:#2f8338}.tdc-key.solve{background:var(--tdc-green-dark);color:#fff;border-color:var(--tdc-green-dark)}.tdc-key.clear{background:#fff4f2;color:#a42f24}.tdc-math-actions{display:grid;grid-template-columns:1fr 1fr;gap:9px;margin-top:12px}.tdc-answer-panel{position:sticky;top:104px}.tdc-answer-card{background:linear-gradient(145deg,#388c31,#2f7d2b);color:#fff;border-radius:22px;padding:22px;min-height:150px}.tdc-answer-card *{color:#fff!important}.tdc-answer-label{font-size:.82rem;font-weight:800;letter-spacing:.08em;text-transform:uppercase}.tdc-answer-value{display:block;font-size:clamp(2rem,5vw,3.4rem);line-height:1.15;margin-top:12px;overflow-wrap:anywhere}.tdc-teach-card{margin-top:14px;border:1px solid #dbe4de;border-radius:20px;padding:19px}.tdc-teach-card h3{margin:0 0 10px}.tdc-teach-step{padding:10px 0;border-top:1px solid #edf1ef;line-height:1.55}.tdc-teach-step:first-child{border-top:0}.math-tabs{display:flex;flex-wrap:wrap;gap:8px}.math-tab{border:1px solid #d6dfda;background:#fff;border-radius:12px;padding:11px 15px;font-weight:800;color:var(--tdc-ink);cursor:pointer}.math-tab.active{background:var(--tdc-green-dark);color:#fff;border-color:var(--tdc-green-dark)}
.ad-slot,.ad-placeholder,.ad-slot *,.ad-placeholder *{color:#737b86!important}
@media(max-width:960px){.tdc-desktop-nav{display:none}.tdc-mobile-nav{display:flex}.tdc-nav-row{min-height:78px}.tdc-category-menu{position:fixed;left:16px;right:16px;top:82px;width:auto;grid-template-columns:1fr 1fr}.tdc-math-shell{grid-template-columns:1fr}.tdc-answer-panel{position:static}.tdc-guidance-grid{grid-template-columns:1fr}.tdc-understand-grid{grid-template-columns:1fr}}
@media(max-width:620px){.tdc-nav-row{padding-left:16px!important;padding-right:16px!important;gap:10px}.tdc-wordmark{font-size:.96rem}.tdc-mobile-nav{gap:6px}.tdc-mobile-nav>a,.tdc-category-button,.tdc-mobile-search{font-size:.78rem;padding:9px 9px}.tdc-category-menu{grid-template-columns:1fr;max-height:70vh;overflow:auto}.tdc-home-main{padding:34px 18px 56px}.tdc-home-intro .tdc-free-title{font-size:clamp(2.55rem,13vw,4.25rem)}.tdc-keypad-row{grid-template-columns:repeat(4,minmax(0,1fr))}.tdc-key{min-height:52px}.tdc-related-grid{grid-template-columns:1fr}.tdc-info-suite{padding:0 18px}.tdc-category-grid{grid-template-columns:1fr!important}}