* { box-sizing: border-box; }
body { margin: 0; background: var(--gray-ee, #eee); color: var(--gray-30, #303030); font: 16px/1.55 system-ui, sans-serif; }
header { display: flex; justify-content: space-between; gap: 1rem; padding: 1rem max(1.25rem, calc((100vw - 1200px)/2)); background: white; border-bottom: 1px solid var(--gray-dd, #ddd); }
a { color: var(--dark-blue, #4879a4); text-underline-offset: .18em; }
header a:first-child { font-weight: 700; }
main { max-width: 1200px; margin: auto; padding: 2rem 1.25rem 4rem; }
main.catalog { max-width: 850px; }
h1 { font-size: clamp(1.7rem, 3vw, 2.4rem); line-height: 1.2; margin: .4rem 0 1rem; }
h2 { font-size: 1.12rem; margin: 0 0 1rem; }
.eyebrow { color: var(--gray-48, #484848); font-size: .74rem; letter-spacing: .1em; }
.session, .room-card, aside section { background: white; border: 1px solid var(--gray-dd, #ddd); padding: 1.2rem; margin: 1rem 0; }
.session { border-left: 4px solid var(--soft-blue, #489add); }
.session p { margin: .3rem 0; }
#session-status { font-weight: 700; }
.classroom-grid { display: grid; grid-template-columns: minmax(0, 1fr) 300px; gap: 1.5rem; margin-top: 2rem; }
aside section:first-child { margin-top: 0; }
.messages { background: white; border: 1px solid var(--gray-dd, #ddd); padding: 0 1.2rem; max-height: 68vh; min-height: 10rem; overflow: auto; scroll-behavior: auto; }
.message { border-bottom: 1px solid var(--gray-dd, #ddd); padding: 1.1rem 0; overflow-wrap: anywhere; }
.message:last-child { border-bottom: none; }
.message-meta { display: flex; flex-wrap: wrap; gap: .3rem .8rem; align-items: baseline; font-size: .77rem; color: var(--gray-48, #484848); }
.message-meta strong { font-size: .95rem; color: var(--gray-30, #303030); }
.message-text { margin: .5rem 0; white-space: pre-wrap; }
.studentjoined, .teacherjoined, .left { color: var(--gray-48, #484848); font-size: .88rem; }
.lecture .message-meta strong, .teacherpost .message-meta strong { color: var(--very-dark-blue, #123048); }
.reply-reference, .muted, form p { font-size: .82rem; color: var(--gray-48, #484848); }
form { margin-top: 1rem; }
label { display: block; margin-top: .7rem; font-size: .9rem; }
input, textarea { font: inherit; padding: .55rem; border: 1px solid var(--gray-79, #797979); border-radius: 2px; width: 100%; background: white; color: inherit; }
textarea { resize: vertical; }
button { font: inherit; border: 1px solid var(--dark-blue, #4879a4); background: var(--very-dark-blue, #123048); color: white; padding: .5rem .9rem; margin: .8rem 0 0; cursor: pointer; border-radius: 2px; }
button.secondary, button.reply-button { color: var(--dark-blue, #4879a4); background: white; }
button.reply-button { font-size: .77rem; padding: .15rem .5rem; margin: 0; }
:focus-visible { outline: 3px solid var(--soft-blue, #489add); outline-offset: 3px; }
ul { padding-left: 1.2rem; }
li { margin-bottom: .6rem; overflow-wrap: anywhere; }
.timetable { list-style: none; padding: 0; }
.timetable li { border-top: 1px solid var(--gray-dd, #ddd); padding-top: .7rem; }
.timetable strong, .timetable span, .timetable time { display: block; }
.timetable time { font-size: .8rem; }
.notice { padding: 1rem 0; }
#connection-status:not(:empty) { color: #783b17; }
#earlier-messages { display: inline-block; margin-top: .7rem; }
#earlier-messages[hidden] { display: none; }
#reply-id { width: 10rem; }
@media (max-width: 780px) { .classroom-grid { grid-template-columns: 1fr; } header { flex-wrap: wrap; } .messages { max-height: 60vh; } }