/* v23 · Κεφάλαιο 4 — Ρευστά: 4.2 έως 4.5 */
.fluid-page{--fluid-accent:#3768ae;--fluid-accent-2:#e66f3f;--fluid-dark:#17233b;--fluid-pale:#edf4ff;--fluid-warm:#fff6ef}
.fluid-page.hydro-page{--fluid-accent:#2f78b7;--fluid-accent-2:#24a6a1;--fluid-pale:#eaf7fb}
.fluid-page.atmos-page{--fluid-accent:#4e67a6;--fluid-accent-2:#e08b45;--fluid-pale:#eef3ff}
.fluid-page.pascal-page{--fluid-accent:#7356b6;--fluid-accent-2:#d96f45;--fluid-pale:#f2effb}
.fluid-page.buoyancy-page{--fluid-accent:#248477;--fluid-accent-2:#e58a3a;--fluid-pale:#eaf8f4}
.fluid-page .fluid-hero{background:radial-gradient(circle at 82% 18%,color-mix(in srgb,var(--fluid-accent) 19%,transparent) 0,transparent 31%),radial-gradient(circle at 75% 84%,color-mix(in srgb,var(--fluid-accent-2) 15%,transparent) 0,transparent 30%),linear-gradient(135deg,#fff 0,#f8fbff 52%,#fff9f4 100%)}
.fluid-page .fluid-hero .lesson-hero-copy h1 em{color:var(--fluid-accent)}
.fluid-page .fluid-hero .reading-audience span{background:var(--fluid-pale);color:var(--fluid-dark)}
.fluid-visual{position:relative;height:450px;overflow:hidden;border-radius:220px 220px 24px 24px;background:linear-gradient(145deg,var(--fluid-pale),#fff0e4);box-shadow:0 26px 60px rgba(38,72,126,.18)}
.fluid-visual svg{width:100%;height:100%;display:block}.fluid-visual text{font-family:Commissioner,Arial,sans-serif;fill:#17233b}.fluid-visual .accent{fill:var(--fluid-accent)}.fluid-visual .accent2{fill:var(--fluid-accent-2)}.fluid-visual .stroke{stroke:#17233b;stroke-width:4;fill:none}.fluid-visual .thin{stroke:#17233b;stroke-width:2;fill:none}.fluid-visual .water{fill:#bfe5f4}.fluid-visual .air{fill:#dce8ff}.fluid-visual .label{font-size:15px;font-weight:800}.fluid-visual .small{font-size:12px;font-weight:650}
.fluid-page .reading-kicker,.fluid-page .syllabus-note>span{color:var(--fluid-accent)}.fluid-page .syllabus-note{border-color:color-mix(in srgb,var(--fluid-accent) 28%,#fff);background:linear-gradient(145deg,#fff,var(--fluid-pale))}
.fluid-equation{margin:28px 0;padding:27px;border-radius:16px;background:linear-gradient(135deg,#17233b,color-mix(in srgb,var(--fluid-accent) 75%,#17233b));color:#fff;text-align:center}.fluid-equation small{display:block;color:#dbe8ff;font-size:9px;font-weight:800;letter-spacing:.14em}.fluid-equation strong{display:block;margin:16px 0;font:650 clamp(30px,4.5vw,50px) Literata,Georgia,serif}.fluid-equation p{margin:0;color:#e9f0fa;font-size:12px}
.fluid-grid,.fluid-apps,.fluid-misconceptions,.fluid-comparison{display:grid;gap:13px;margin:28px 0}.fluid-grid,.fluid-comparison,.fluid-misconceptions{grid-template-columns:1fr 1fr}.fluid-apps{grid-template-columns:repeat(3,1fr)}
.fluid-grid article,.fluid-apps article,.fluid-comparison article,.fluid-misconceptions article{padding:22px;border:1px solid #dbe4ee;border-radius:13px;background:#fff}.fluid-grid span,.fluid-apps span,.fluid-comparison span{display:block;color:var(--fluid-accent);font-size:9px;font-weight:800;letter-spacing:.12em}.fluid-grid strong,.fluid-apps strong,.fluid-comparison strong{display:block;margin:8px 0;color:#17233b;font:650 20px Literata,Georgia,serif}.fluid-grid p,.fluid-apps p,.fluid-comparison p{margin:0;font-size:11px}.fluid-misconceptions article{background:#fff8f2;border-color:#efd9cb}.fluid-misconceptions strong{display:block;color:#a64e2a;font-size:12px}.fluid-misconceptions p{margin:8px 0 0;font-size:11px}
.fluid-note{margin:26px 0;padding:22px;border-left:5px solid var(--fluid-accent);border-radius:0 12px 12px 0;background:var(--fluid-pale)}.fluid-note strong{display:block;color:#17233b}.fluid-note p{margin:7px 0 0}.fluid-warning{margin:26px 0;padding:22px;border-left:5px solid var(--fluid-accent-2);border-radius:0 12px 12px 0;background:#fff5ee}.fluid-warning strong{display:block;color:#9a4729}.fluid-warning p{margin:7px 0 0}
.fluid-table{width:100%;border-collapse:collapse;margin:25px 0;font-size:12px}.fluid-table th,.fluid-table td{padding:13px;border:1px solid #dce5ef;text-align:left}.fluid-table th{background:var(--fluid-pale);color:#17233b}.fluid-table tr:nth-child(even) td{background:#fbfdff}
.fluid-inquiry{margin:28px 0;padding:28px;border:1px solid #dbe5f0;border-radius:15px;background:linear-gradient(145deg,#f8fbff,#fff8f3)}.fluid-inquiry ol,.fluid-inquiry ul{margin:16px 0 0;padding-left:20px}.fluid-inquiry li{margin:8px 0}
.fluid-page .mm-solution>span,.fluid-page .mm-practice article>span{color:var(--fluid-accent)}.fluid-page .mm-quiz summary:after{color:var(--fluid-accent)}.fluid-page .mm-quiz details[open] summary{background:var(--fluid-pale)}
.fluid-force-diagram{display:flex;justify-content:center;align-items:center;gap:34px;margin:28px 0;padding:28px;border:1px solid #dce5ef;border-radius:15px;background:#fbfdff}.fluid-force-diagram .body{position:relative;width:110px;height:115px;border:3px solid #17233b;border-radius:12px;background:#fff}.fluid-force-diagram .arrow-up,.fluid-force-diagram .arrow-down{position:absolute;left:50%;width:5px;border-radius:5px;transform:translateX(-50%)}.fluid-force-diagram .arrow-up{height:76px;top:-82px;background:var(--fluid-accent)}.fluid-force-diagram .arrow-down{height:76px;bottom:-82px;background:var(--fluid-accent-2)}.fluid-force-diagram .arrow-up:before{content:'';position:absolute;left:50%;top:-1px;transform:translate(-50%,-60%);border-left:10px solid transparent;border-right:10px solid transparent;border-bottom:15px solid var(--fluid-accent)}.fluid-force-diagram .arrow-down:after{content:'';position:absolute;left:50%;bottom:-1px;transform:translate(-50%,60%);border-left:10px solid transparent;border-right:10px solid transparent;border-top:15px solid var(--fluid-accent-2)}.fluid-force-diagram b{font-size:13px;color:#17233b}
@media(max-width:760px){.fluid-visual{height:340px;border-radius:145px 145px 16px 16px}.fluid-grid,.fluid-apps,.fluid-comparison,.fluid-misconceptions{grid-template-columns:1fr}.fluid-force-diagram{padding:80px 20px;gap:18px}}