:root{--blue:#1865f2;--blue-dark:#1648ad;--ink:#21242c;--muted:#626975;--paper:#fff;--pale:#f3f7ff;--green:#d7f2a1;--line:#e3e6ec;--display:'DM Sans',Arial,sans-serif;--sans:'DM Sans',Arial,sans-serif}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--sans);-webkit-font-smoothing:antialiased}button,a,input{font:inherit}a{color:inherit;text-decoration:none}.site-header{height:76px;display:flex;align-items:center;justify-content:space-between;padding:0 max(6%,calc((100% - 1160px)/2));border-bottom:1px solid #edf0f3;background:white;position:relative;z-index:5}.brand{display:flex;align-items:center;gap:10px;font:700 17px/1.1 var(--display);letter-spacing:-.35px}.brand-mark{width:36px;height:36px;flex:none}.brand small{display:block;margin-top:4px;font:600 7px/1 var(--sans);letter-spacing:1.25px;color:#747b86}.main-nav{display:flex;align-items:center;gap:30px;font-size:12px;font-weight:600;color:#4b515b}.main-nav a:hover{color:var(--blue)}.header-login{border:1px solid #cbd9f6;background:white;color:var(--blue);padding:10px 15px;border-radius:5px;font-size:11px;font-weight:700;cursor:pointer}.header-login:hover{background:#f4f7ff}.header-login span{margin-left:12px}.menu-toggle{display:none}.hero{max-width:1160px;margin:0 auto;min-height:540px;padding:70px 0 0;display:grid;grid-template-columns:1fr .95fr;gap:7%;position:relative}.hero-copy{padding-top:23px}.eyebrow,.section-kicker,.closing-kicker{font-size:10px;font-weight:700;letter-spacing:.8px;color:#526170}.eyebrow{display:flex;align-items:center;gap:8px}.eyebrow-dot{height:9px;width:9px;border-radius:50%;display:inline-block;background:#62a344}.hero h1{font:700 clamp(45px,5.1vw,66px)/1.08 var(--display);letter-spacing:-2.9px;margin:20px 0 19px;color:#20232b}.hero h1 em{color:var(--blue);font-style:normal}.hero-lede{max-width:430px;font-size:15px;line-height:1.7;color:#59616d;margin:0}.hero-actions{display:flex;align-items:center;gap:20px;margin-top:25px}.button{display:inline-flex;justify-content:center;align-items:center;gap:21px;min-height:45px;padding:0 17px;border:0;border-radius:5px;font-size:11px;font-weight:700;cursor:pointer;transition:background .18s}.button-dark{background:var(--blue);color:white}.button-dark:hover{background:#1056d3}.button span{font-size:16px}.text-action{border:0;background:none;padding:0;color:#65707d;font-size:10px;line-height:1.8;text-align:left;cursor:pointer}.text-action span{display:block;color:var(--blue);font-size:11px;font-weight:700}.hero-proof{display:flex;align-items:center;gap:10px;margin-top:26px;color:#656d78;font-size:10px;line-height:1.55}.hero-proof b{color:#2d3540}.proof-check{width:23px;height:23px;display:grid;place-items:center;border-radius:50%;background:#eaf4df;color:#49852f;font-weight:700}.hero-art{height:400px;margin-top:0;position:relative;background:#f0f6ff;border-radius:10px;display:grid;place-items:center;overflow:hidden}.lesson-sheet{position:relative;z-index:1;background:white;border:1px solid #e2e8f0;border-radius:7px;width:min(84%,390px);padding:24px 25px;box-shadow:0 7px 22px rgba(33,61,100,.09);transform:rotate(-1deg)}.lesson-label{display:flex;align-items:center;justify-content:space-between;color:#43803c;font-size:8px;font-weight:700;letter-spacing:.7px}.lesson-grade{color:#7a8390;font-weight:600;font-size:7px}.lesson-sheet h2{font:700 19px/1.25 var(--display);letter-spacing:-.4px;margin:17px 0 8px}.lesson-question{font-size:10px;line-height:1.55;color:#69727e;margin:0}.apple-groups{margin:19px 0 15px;display:flex;justify-content:space-between;gap:9px}.apple-groups div{height:44px;flex:1;border:1px solid #dce5f2;border-radius:5px;display:flex;justify-content:center;align-items:center;gap:4px;white-space:nowrap;color:#e17d54;font-size:11px}.lesson-equation{display:flex;align-items:center;justify-content:space-between;border-top:1px solid #edf0f4;padding-top:13px;color:#56606d;font-size:10px}.lesson-equation b{font-size:17px;color:var(--blue)}.lesson-tip{margin-top:14px;padding:9px 10px;border-radius:4px;background:#f1f8e7;color:#56634d;font-size:9px}.lesson-tip span{color:#7c9d36;margin-right:6px}.doodle{position:absolute;color:var(--blue);font-family:Georgia,serif}.doodle-plus{right:9%;top:40px;font-size:38px;transform:rotate(10deg)}.doodle-star{left:9%;top:57px;color:#e8a348;font-size:24px}.doodle-check{right:9%;bottom:47px;color:#63a44a;font-size:29px;transform:rotate(8deg)}.art-caption{position:absolute;bottom:17px;left:20px;right:20px;border-top:1px solid #dce6f3;padding-top:10px;color:#758194;font-size:7px;letter-spacing:1.1px;font-weight:700}.hero-bottom{grid-column:1/-1;border-top:1px solid var(--line);margin-top:33px;height:55px;display:flex;align-items:center;justify-content:space-between;color:#65707c;font-size:10px}.hero-bottom b{color:#253247}.scroll-cue{font-size:8px;letter-spacing:.8px;font-weight:700}.scroll-cue span{margin-left:8px;color:var(--blue);font-size:14px}.section{padding-left:max(8%,calc((100% - 1000px)/2));padding-right:max(8%,calc((100% - 1000px)/2))}.approach{padding-top:75px;padding-bottom:78px}.section-kicker{color:#5e6c7d}.approach-heading{display:flex;align-items:flex-end;justify-content:space-between;margin:14px 0 35px}.approach-heading h2,.subject-intro h2,.closing h2{font:700 clamp(34px,4vw,47px)/1.1 var(--display);letter-spacing:-1.5px;margin:0}.approach-heading p{max-width:390px;color:#66707c;font-size:12px;line-height:1.75;margin:0 0 3px 35px}.feature-grid{display:grid;grid-template-columns:repeat(3,1fr);border-top:1px solid var(--line);border-bottom:1px solid var(--line)}.feature{position:relative;padding:22px 25px 25px 0;min-height:195px}.feature+.feature{border-left:1px solid var(--line);padding-left:25px}.feature-number{font-size:9px;color:#78828e;font-weight:700}.feature-icon{position:absolute;right:19px;top:15px;width:33px;height:33px;display:grid;place-items:center;border-radius:7px;font-size:17px}.icon-sun{color:#437a2c;background:#edf6e3}.icon-leaf{color:#a26531;background:#fff1df}.icon-dot{color:#2c67c6;background:#eaf1ff}.feature h3{font:700 15px var(--display);margin:26px 0 9px}.feature p{max-width:255px;font-size:10px;line-height:1.75;color:#68717c;min-height:52px;margin:0 0 13px}.feature a,.underlined-link{font-size:10px;font-weight:700;color:var(--blue)}.feature a span,.underlined-link span{margin-left:8px}.subjects{padding-top:69px;padding-bottom:76px;background:#f3f7fc;display:grid;grid-template-columns:.9fr 1.1fr;gap:9%}.subject-intro h2{margin:17px 0 14px}.subject-intro h2 em{color:var(--blue);font-style:normal}.subject-intro p{font-size:11px;line-height:1.75;color:#66717d;max-width:310px;margin:0 0 19px}.underlined-link{padding-bottom:6px;border-bottom:1px solid #aac2f0}.subject-list{padding-top:8px}.subject-list>div:not(.subject-footnote){height:55px;display:grid;grid-template-columns:37px 1fr 24px;align-items:center;border-bottom:1px solid #dce4ee;font-size:12px;font-weight:600}.subject-index{font-size:9px;color:#7b8795;font-weight:600}.subject-arrow{font-size:16px;color:var(--blue);text-align:right}.subject-footnote{font-size:10px;color:#7c8692;padding-top:14px}.closing{position:relative;overflow:hidden;text-align:center;background:#eaf3ff;color:#202a39;padding:67px 20px 69px}.closing-decoration{position:absolute;left:12%;top:-70px;font:300 260px Georgia,serif;color:rgba(24,101,242,.06);transform:rotate(-12deg)}.closing-kicker{color:#536e9c}.closing h2{font-size:clamp(38px,4.5vw,54px);margin:15px 0 11px}.closing h2 em{color:var(--blue);font-style:normal}.closing p{font-size:11px;color:#5d6877;margin:0 0 19px}.button-light{background:var(--blue);color:white}.button-light:hover{background:#1056d3}.closing-stamp{position:absolute;right:12%;bottom:28px;border:1px solid #bed2f1;width:66px;height:66px;border-radius:50%;display:grid;place-content:center;font-size:7px;letter-spacing:1px;line-height:1.45;transform:rotate(8deg);color:#60799e}footer{min-height:78px;padding:16px max(6%,calc((100% - 1160px)/2));display:flex;align-items:center;justify-content:space-between;color:#727a85;font-size:9px}.footer-brand{font-size:15px;color:var(--ink)}.footer-brand .brand-mark{width:31px;height:31px}.modal-backdrop{position:fixed;z-index:10;inset:0;background:rgba(28,43,66,.42);display:grid;place-items:center;padding:20px;backdrop-filter:blur(2px)}.modal-backdrop[hidden]{display:none}.login-modal{position:relative;background:white;width:min(100%,410px);padding:32px 38px 27px;box-shadow:0 16px 55px rgba(30,48,78,.2);border-radius:7px;animation:modal-in .2s ease-out}.modal-close{position:absolute;right:15px;top:12px;border:0;background:none;color:#596474;font-size:24px;cursor:pointer}.modal-brand{margin-bottom:27px;font-size:16px}.modal-brand .brand-mark{width:32px;height:32px}.login-modal .section-kicker{font-size:9px}.login-modal h2{font:700 33px/1.08 var(--display);letter-spacing:-1px;margin:11px 0 21px}.login-modal form label{display:block;font-size:10px;font-weight:700;color:#414b58;margin:13px 0 6px}.login-modal input{height:42px;width:100%;border:1px solid #cfd5df;background:white;padding:0 11px;border-radius:4px;outline:none;font-size:11px}.login-modal input:focus{border-color:var(--blue);box-shadow:0 0 0 2px #e6efff}.form-message{min-height:16px;margin:7px 0;color:#a54f3e;font-size:9px}.form-message.success{color:#527348}.modal-submit{width:100%;justify-content:space-between;margin-top:1px}.invite-note{display:flex;gap:10px;margin-top:19px;padding:12px;background:#f3f7fc;color:#66717c;font-size:9px;line-height:1.65;border-radius:4px}.invite-note b{color:#344252}.invite-icon{color:var(--blue);font-size:14px}.demo-hint{text-align:center;color:#858e99;font-size:8px;margin:12px 0 0}.student-space{position:fixed;inset:0;z-index:20;background:#090a0a}.student-space[hidden]{display:none}@keyframes modal-in{from{opacity:0;transform:translateY(7px)}to{opacity:1;transform:translateY(0)}}@media(max-width:1200px){.hero{margin-left:6%;margin-right:6%}.hero h1{font-size:58px}}@media(max-width:850px){.site-header{padding:0 5%;height:70px}.main-nav{gap:17px}.hero{padding-top:55px;gap:4%;min-height:510px}.hero h1{font-size:49px}.hero-art{height:365px}.section{padding-left:7%;padding-right:7%}.approach{padding-top:65px}.subjects{gap:6%}.closing-stamp{right:5%}}@media(max-width:650px){.site-header{height:66px}.brand{font-size:14px;gap:7px}.brand-mark{width:31px;height:31px}.brand small{font-size:6px;letter-spacing:.9px}.main-nav{display:none;position:absolute;top:65px;left:0;right:0;background:#fff;padding:18px 6%;border-bottom:1px solid var(--line);flex-direction:column;align-items:flex-start;gap:17px}.main-nav.open{display:flex}.header-login{margin-left:auto;margin-right:11px;padding:9px 10px;font-size:9px}.header-login span{margin-left:5px}.menu-toggle{display:flex;width:28px;height:28px;flex-direction:column;justify-content:center;gap:5px;border:0;background:none;padding:4px}.menu-toggle span{width:19px;height:2px;background:#34404d}.hero{padding:39px 6% 0;margin:0;display:flex;flex-direction:column;gap:0}.hero-copy{padding-top:0}.hero h1{font-size:clamp(43px,12.5vw,59px);letter-spacing:-2.1px;margin:18px 0 13px}.hero-lede{font-size:12px;max-width:380px}.hero-actions{gap:14px;margin-top:19px}.button{min-height:42px;padding:0 13px;gap:13px;font-size:10px}.text-action{font-size:8px}.hero-proof{margin-top:19px}.hero-art{margin-top:26px;height:330px}.lesson-sheet{width:min(86%,355px);padding:20px 18px}.lesson-sheet h2{font-size:17px;margin-top:14px}.apple-groups div{font-size:9px;gap:2px;height:39px}.lesson-equation b{font-size:15px}.hero-bottom{width:100%;margin-top:15px;height:48px}.section{padding-left:7%;padding-right:7%}.approach{padding-top:61px;padding-bottom:59px}.approach-heading{display:block;margin:13px 0 25px}.approach-heading h2,.subject-intro h2{font-size:39px}.approach-heading p{margin:13px 0 0;font-size:11px}.feature-grid{grid-template-columns:1fr}.feature,.feature+.feature{padding:18px 45px 19px 0;min-height:0;border-left:0;border-bottom:1px solid var(--line)}.feature:last-child{border-bottom:0}.feature h3{margin:16px 0 7px}.feature p{min-height:0;max-width:400px;margin-bottom:9px}.feature-icon{right:1px;top:13px}.subjects{grid-template-columns:1fr;gap:28px;padding-top:57px;padding-bottom:59px}.subject-list{padding-top:0}.subject-list>div:not(.subject-footnote){height:52px;font-size:11px}.closing{padding:58px 18px 61px}.closing h2{font-size:42px}.closing-stamp{display:none}footer{padding:18px 6%;display:grid;grid-template-columns:1fr auto;gap:12px;font-size:8px}footer>span:nth-child(2){grid-column:1/-1;grid-row:2}.footer-brand{grid-column:1;grid-row:1}.login-modal{padding:31px 25px 23px}.login-modal h2{font-size:31px}}@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*::before,*::after{animation-duration:.01ms!important;transition-duration:.01ms!important}}
.account-actions{display:flex;align-items:center;gap:9px}.header-signup{border:0;background:var(--blue);color:#fff;padding:10px 15px;border-radius:5px;font-size:11px;font-weight:700;cursor:pointer}.header-signup:hover{background:#1056d3}.modal-switch{text-align:center;margin:15px 0 0;color:#68717c;font-size:10px}.modal-switch button{border:0;background:none;padding:0;color:var(--blue);font-size:inherit;font-weight:700;cursor:pointer}.invite-note{margin-top:12px}#invite-field[hidden]{display:none}@media(max-width:650px){.account-actions{margin-left:auto;margin-right:7px;gap:5px}.header-signup{padding:9px 9px;font-size:9px}.header-login{margin-left:0;margin-right:0}}

/* Tutoring preview and worked example */
.tutoring{display:grid;grid-template-columns:1.05fr .8fr;align-items:center;gap:9%;padding-top:76px;padding-bottom:80px;background:#fff}
.tutoring-copy h2{font:700 clamp(34px,4vw,47px)/1.1 var(--display);letter-spacing:-1.5px;margin:15px 0}
.tutoring-copy h2 em{color:var(--blue);font-style:normal}
.tutoring-copy>p{max-width:480px;color:#66707c;font-size:12px;line-height:1.8;margin:0 0 22px}
.tutoring-steps{border-top:1px solid var(--line)}
.tutoring-steps article{display:grid;grid-template-columns:36px 1fr;gap:8px;padding:14px 0;border-bottom:1px solid var(--line)}
.tutoring-steps article>span{font-size:9px;font-weight:700;color:#78828e;padding-top:2px}
.tutoring-steps h3{font:700 13px var(--display);margin:0 0 4px}
.tutoring-steps p{font-size:10px;line-height:1.6;color:#68717c;margin:0}
.practice-card{padding:24px 25px 19px;border:1px solid #dce4ef;border-radius:8px;background:#f8fbff;box-shadow:0 8px 26px rgba(34,66,105,.07)}
.practice-card-top{display:flex;justify-content:space-between;gap:8px;color:#527246;font-size:8px;font-weight:700;letter-spacing:.7px}
.practice-card-top span+span{color:#7b8592}
.practice-card h3{font:700 17px/1.35 var(--display);margin:20px 0 8px}
.practice-prompt{font-size:11px;color:#67717e;margin:0}
.practice-equation{padding:19px 0;text-align:center;color:#1f2c40;font:700 31px Georgia,serif;letter-spacing:2px}
.practice-card details{border-top:1px solid #e0e7f0;padding-top:12px}
.practice-card summary{color:var(--blue);font-size:10px;font-weight:700;cursor:pointer}
.practice-answer{padding:8px 0 3px;color:#596575;font-size:10px;line-height:1.6}
.practice-answer p{margin:7px 0 3px}
.practice-answer b{display:block;color:#253248;font:700 15px Georgia,serif}
.practice-answer .answer-check{color:#4e7e3c;font-weight:600;margin-top:10px}
.practice-card-foot{margin-top:14px;padding-top:12px;border-top:1px solid #e0e7f0;color:#7a8491;font-size:9px;line-height:1.6}
.account-notice{margin:10px 0 0;color:#7a8491;font-size:9px;line-height:1.55}
@media(max-width:650px){.tutoring{grid-template-columns:1fr;gap:28px;padding-top:57px;padding-bottom:60px}.tutoring-copy h2{font-size:39px}.practice-card{padding:20px}}