/* ============================================================
   Yelin Theme System — CSS Variables + Base Styles
   All visual properties driven by CSS custom properties.
   Switching themes = swapping variable values.
   ============================================================ */

/* === DEFAULT THEME: 木色调 Woodgrain === */
:root {
  /* --- Core --- */
  --yl-accent: #c49a6c;
  --yl-accent-hover: #d4a87a;
  --yl-accent-subtle: rgba(196,154,108,0.15);
  --yl-accent-text: #fff;

  /* --- Background --- */
  --yl-bg: #2a2218;
  --yl-bg-secondary: #1e1a14;
  --yl-bg-gradient: linear-gradient(160deg, #2a2218 0%, #1e1a14 100%);
  --yl-bg-image: none;
  --yl-bg-overlay: rgba(0,0,0,0);

  /* --- Chat area --- */
  --yl-chat-bg: transparent;

  /* --- Bubbles: them --- */
  --yl-bubble-them-bg: #3a3028;
  --yl-bubble-them-text: #e8ddd0;
  --yl-bubble-them-border: rgba(196,154,108,0.15);

  /* --- Bubbles: me --- */
  --yl-bubble-me-bg: rgba(196,154,108,0.22);
  --yl-bubble-me-text: #f5f0e8;
  --yl-bubble-me-border: rgba(196,154,108,0.32);

  /* --- Bubble geometry --- */
  --yl-bubble-radius: 16px;
  --yl-bubble-tail: 0;  /* 0=none, 1=show */
  --yl-bubble-padding: 10px 14px;
  --yl-bubble-gap: 8px;
  --yl-bubble-them-width: 75%;
  --yl-bubble-me-width: 70%;
  --yl-msg-spacing: compact; /* compact | normal | relaxed */

  /* --- Typography --- */
  --yl-font-family: -apple-system, "SF Pro", "PingFang SC", "Microsoft YaHei", sans-serif;
  --yl-font-size: 15px;
  --yl-font-size-mobile: 16px;
  --yl-line-height: 1.65;
  --yl-msg-font-weight: 400;

  /* --- Avatars --- */
  --yl-avatar-them-size: 32px;
  --yl-avatar-me-size: 36px;
  --yl-avatar-them-radius: 50%;
  --yl-avatar-me-radius: 50%;
  --yl-avatar-them-src: none;
  --yl-avatar-me-src: none;
  --yl-show-avatar-them: 1;
  --yl-show-avatar-me: 0;

  /* --- Name display --- */
  --yl-name-them-display: block;
  --yl-name-them-size: 12px;
  --yl-name-them-color: var(--yl-accent);

  /* --- Timestamp --- */
  --yl-ts-display: none;  /* none | block | inline */
  --yl-ts-size: 11px;
  --yl-ts-color: rgba(255,255,255,0.3);
  --yl-ts-position: below; /* below | inline | hover */

  /* --- Input area --- */
  --yl-input-bg: #3a3028;
  --yl-input-text: #e8ddd0;
  --yl-input-border: rgba(196,154,108,0.2);
  --yl-input-radius: 20px;
  --yl-input-height: 44px;
  --yl-input-focus-border: var(--yl-accent);

  /* --- Send button --- */
  --yl-send-bg: var(--yl-accent);
  --yl-send-text: #fff;
  --yl-send-radius: 50%;
  --yl-send-size: 40px;

  /* --- Sidebar --- */
  --yl-sidebar-bg: #1e1a14;
  --yl-sidebar-text: #c4b8a8;
  --yl-sidebar-active-bg: rgba(196,154,108,0.12);
  --yl-sidebar-width: 350px;

  /* --- Panel / Settings --- */
  --yl-panel-bg: #2a2218;
  --yl-panel-text: #e8ddd0;
  --yl-panel-border: rgba(196,154,108,0.15);

  /* --- Scrollbar --- */
  --yl-scrollbar-width: 6px;
  --yl-scrollbar-track: transparent;
  --yl-scrollbar-thumb: rgba(196,154,108,0.3);

  /* --- Glass effect --- */
  --yl-glass-blur: 0px;
  --yl-glass-opacity: 1;

  /* --- Transitions --- */
  --yl-transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);

  /* --- Selection --- */
  --yl-selection-bg: rgba(196,154,108,0.3);
  --yl-selection-text: #fff;

  /* --- System messages --- */
  --yl-system-bg: rgba(196,154,108,0.06);
  --yl-system-text: rgba(255,255,255,0.4);
  --yl-system-size: 12px;

  /* --- Max chat width (desktop) --- */
  --yl-chat-max-width: 768px;

  /* --- Header --- */
  --yl-header-bg: rgba(30,26,20,0.85);
  --yl-header-text: #e8ddd0;
  --yl-header-height: 52px;

  /* --- Misc --- */
  --yl-link-color: var(--yl-accent);
  --yl-danger: #d44;
  --yl-success: #4a8;
  --yl-warning: #da3;
  --yl-border-color: rgba(255,255,255,0.08);
}

/* === THEME: 灰蓝深红 Steel & Crimson === */
[data-theme="steel"] {
  --yl-accent: #c43838;
  --yl-accent-hover: #d84848;
  --yl-accent-subtle: rgba(196,56,56,0.10);
  --yl-accent-text: #fff;
  --yl-bg: #14181f;
  --yl-bg-secondary: #0f1318;
  --yl-bg-gradient: linear-gradient(160deg, #14181f 0%, #0f1318 100%);
  --yl-bubble-them-bg: #1c2230;
  --yl-bubble-them-text: #c8cdd8;
  --yl-bubble-them-border: rgba(100,130,180,0.12);
  --yl-bubble-me-bg: rgba(196,56,56,0.16);
  --yl-bubble-me-text: #f0e8e8;
  --yl-bubble-me-border: rgba(196,56,56,0.28);
  --yl-input-bg: #1a2030;
  --yl-input-text: #c8cdd8;
  --yl-input-border: rgba(100,130,180,0.15);
  --yl-sidebar-bg: #0f1318;
  --yl-sidebar-text: #7888a0;
  --yl-sidebar-active-bg: rgba(196,56,56,0.10);
  --yl-panel-bg: #14181f;
  --yl-panel-text: #c8cdd8;
  --yl-panel-border: rgba(100,130,180,0.12);
  --yl-header-bg: rgba(15,19,24,0.92);
  --yl-header-text: #c8cdd8;
  --yl-scrollbar-thumb: rgba(196,56,56,0.25);
  --yl-system-text: rgba(200,210,230,0.3);
  --yl-ts-color: rgba(200,210,230,0.25);
  --yl-name-them-color: #8090b0;
  --yl-selection-bg: rgba(196,56,56,0.3);
}

/* === THEME: 深渊 Abyss === */
[data-theme="abyss"] {
  --yl-accent: #6080a0;
  --yl-accent-hover: #7898b8;
  --yl-accent-subtle: rgba(96,128,160,0.08);
  --yl-accent-text: #e8f0f8;
  --yl-bg: #08090c;
  --yl-bg-secondary: #050608;
  --yl-bg-gradient: linear-gradient(180deg, #08090c 0%, #040508 100%);
  --yl-bubble-them-bg: #10121a;
  --yl-bubble-them-text: #a0b0c8;
  --yl-bubble-them-border: rgba(96,128,160,0.10);
  --yl-bubble-me-bg: rgba(96,128,160,0.10);
  --yl-bubble-me-text: #b8c8e0;
  --yl-bubble-me-border: rgba(96,128,160,0.16);
  --yl-input-bg: #10121a;
  --yl-input-text: #a0b0c8;
  --yl-input-border: rgba(96,128,160,0.18);
  --yl-sidebar-bg: #050608;
  --yl-sidebar-text: #607080;
  --yl-sidebar-active-bg: rgba(96,128,160,0.06);
  --yl-panel-bg: #08090c;
  --yl-panel-text: #a0b0c8;
  --yl-panel-border: rgba(96,128,160,0.10);
  --yl-header-bg: rgba(5,6,8,0.95);
  --yl-header-text: #a0b0c8;
  --yl-scrollbar-thumb: rgba(96,128,160,0.15);
  --yl-system-text: rgba(128,152,176,0.2);
  --yl-ts-color: rgba(128,152,176,0.2);
  --yl-name-them-color: #6080a0;
  --yl-selection-bg: rgba(96,128,160,0.2);
}

/* === THEME: 蔷薇 Rose === */
[data-theme="rose"] {
  --yl-accent: #d4687a;
  --yl-accent-hover: #e07888;
  --yl-accent-subtle: rgba(212,104,122,0.10);
  --yl-accent-text: #fff;
  --yl-bg: #f8f0f0;
  --yl-bg-secondary: #f5eced;
  --yl-bg-gradient: linear-gradient(160deg, #f8f0f0 0%, #f0e0e4 100%);
  --yl-bubble-them-bg: #ecd4dc;
  --yl-bubble-them-text: #4a2530;
  --yl-bubble-them-border: rgba(212,104,122,0.25);
  --yl-bubble-me-bg: rgba(212,104,122,0.22);
  --yl-bubble-me-text: #3a1c24;
  --yl-bubble-me-border: rgba(212,104,122,0.35);
  --yl-input-bg: #f5e8ec;
  --yl-input-text: #4a2530;
  --yl-input-border: rgba(212,104,122,0.2);
  --yl-sidebar-bg: #f5eced;
  --yl-sidebar-text: #8a5060;
  --yl-sidebar-active-bg: rgba(212,104,122,0.10);
  --yl-panel-bg: #f8f0f0;
  --yl-panel-text: #4a2530;
  --yl-panel-border: rgba(212,104,122,0.15);
  --yl-header-bg: rgba(245,236,237,0.9);
  --yl-header-text: #4a2530;
  --yl-scrollbar-thumb: rgba(212,104,122,0.25);
  --yl-system-text: rgba(74,37,48,0.3);
  --yl-ts-color: rgba(74,37,48,0.3);
  --yl-name-them-color: var(--yl-accent);
  --yl-selection-bg: rgba(212,104,122,0.25);
  --yl-selection-text: #3a1c24;
}

/* ============================================================
   BASE LAYOUT + COMPONENTS
   ============================================================ */

*, *::before, *::after { box-sizing: border-box; }

html {
  font-size: var(--yl-font-size);
  -webkit-font-smoothing: antialiased;
}

body {
  margin: 0;
  padding: 0;
  font-family: var(--yl-font-family);
  background: var(--yl-bg-gradient);
  background-color: var(--yl-bg);
  color: var(--yl-panel-text);
  line-height: var(--yl-line-height);
  min-height: 100vh;
  overflow: hidden;
  transition: background var(--yl-transition), color var(--yl-transition);
}

/* Background image support */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  background-image: var(--yl-bg-image);
  background-size: cover;
  background-position: center;
  opacity: var(--yl-glass-opacity);
  z-index: -1;
  pointer-events: none;
}

::selection {
  background: var(--yl-selection-bg);
  color: var(--yl-selection-text);
}

/* --- Scrollbar --- */
::-webkit-scrollbar { width: var(--yl-scrollbar-width); }
::-webkit-scrollbar-track { background: var(--yl-scrollbar-track); }
::-webkit-scrollbar-thumb {
  background: var(--yl-scrollbar-thumb);
  border-radius: 99px;
}
::-webkit-scrollbar-thumb:hover { background: var(--yl-accent); }

/* --- Links --- */
a { color: var(--yl-link-color); text-decoration: none; }
a:hover { opacity: 0.8; }

/* --- App Layout --- */
.yl-app {
  display: flex;
  height: 100vh;
  width: 100%;
}

/* --- Main content --- */
.yl-main {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
  position: relative;
}

/* --- Header --- */
.yl-header {
  height: var(--yl-header-height);
  background: var(--yl-header-bg);
  backdrop-filter: blur(var(--yl-glass-blur));
  -webkit-backdrop-filter: blur(var(--yl-glass-blur));
  color: var(--yl-header-text);
  display: flex;
  align-items: center;
  padding: 0 16px;
  gap: 12px;
  border-bottom: 1px solid var(--yl-border-color);
  z-index: 10;
}

.yl-header-title {
  font-size: 16px;
  font-weight: 600;
}

.yl-header-status {
  font-size: 12px;
  opacity: 0.5;
}

.yl-header-actions {
  margin-left: auto;
  display: flex;
  gap: 8px;
}

/* --- Chat area --- */
.yl-chat {
  flex: 1;
  overflow-y: auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  background: var(--yl-chat-bg);
}

.yl-chat-inner {
  max-width: var(--yl-chat-max-width);
  width: 100%;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
}

/* --- Message wrapper --- */
.yl-msg {
  display: flex;
  gap: 8px;
  margin-bottom: var(--yl-bubble-gap);
  max-width: 100%;
}

.yl-msg.them { align-self: flex-start; }
.yl-msg.me { align-self: flex-end; flex-direction: row-reverse; }

/* Spacing modes */
[data-msg-spacing="compact"] .yl-msg { margin-bottom: 4px; }
[data-msg-spacing="relaxed"] .yl-msg { margin-bottom: 16px; }

/* --- Avatar --- */
.yl-avatar {
  width: var(--yl-avatar-them-size);
  height: var(--yl-avatar-them-size);
  border-radius: var(--yl-avatar-them-radius);
  background: var(--yl-accent-subtle);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  color: var(--yl-accent);
  overflow: hidden;
  background-size: cover;
  background-position: center;
}
.yl-msg.me .yl-avatar {
  width: var(--yl-avatar-me-size);
  height: var(--yl-avatar-me-size);
  border-radius: var(--yl-avatar-me-radius);
}

/* --- Bubble --- */
.yl-bubble {
  padding: var(--yl-bubble-padding);
  border-radius: var(--yl-bubble-radius);
  font-size: 1rem;
  font-weight: var(--yl-msg-font-weight);
  line-height: var(--yl-line-height);
  word-break: break-word;
  position: relative;
  transition: background var(--yl-transition), color var(--yl-transition);
}

.yl-msg.them .yl-bubble {
  background: var(--yl-bubble-them-bg);
  color: var(--yl-bubble-them-text);
  border: 1px solid var(--yl-bubble-them-border);
  max-width: var(--yl-bubble-them-width);
  width: fit-content;
}
.yl-msg.me .yl-bubble {
  background: var(--yl-bubble-me-bg);
  color: var(--yl-bubble-me-text);
  border: 1px solid var(--yl-bubble-me-border);
  max-width: var(--yl-bubble-me-width);
  width: fit-content;
}

/* Directional corner rounding — sharper on avatar side */
.yl-msg.them .yl-bubble { border-top-left-radius: 4px; }
.yl-msg.me .yl-bubble { border-top-right-radius: 4px; }

/* Bubble tail (optional) */
.yl-msg.them .yl-bubble::before,
.yl-msg.me .yl-bubble::before {
  content: "";
  position: absolute;
  top: 12px;
  width: 0; height: 0;
  border: 6px solid transparent;
  display: none;
}
[data-bubble-tail="1"] .yl-msg.them .yl-bubble::before {
  display: block;
  left: -11px;
  border-right-color: var(--yl-bubble-them-bg);
}
[data-bubble-tail="1"] .yl-msg.me .yl-bubble::before {
  display: block;
  right: -11px;
  border-left-color: var(--yl-bubble-me-bg);
}

/* --- Name --- */
.yl-msg-name {
  display: var(--yl-name-them-display);
  font-size: var(--yl-name-them-size);
  color: var(--yl-name-them-color);
  margin-bottom: 2px;
  font-weight: 500;
}
.yl-msg.me .yl-msg-name { display: none; }

/* --- Timestamp --- */
.yl-msg-ts {
  display: var(--yl-ts-display);
  font-size: var(--yl-ts-size);
  color: var(--yl-ts-color);
  margin-top: 4px;
}

/* --- Delivery status --- */
.yl-delivery {
  font-size: 11px;
  margin-top: 2px;
}
.yl-delivery[data-status="sending"] { color: var(--yl-ts-color); }
.yl-delivery[data-status="sending"]::after { content: "..."; animation: yl-pulse 1.2s infinite; }
.yl-delivery[data-status="delivered"] { color: var(--yl-success); }
.yl-delivery[data-status="delivered"]::after { content: "\2713"; }
.yl-delivery[data-status="failed"] { color: var(--yl-danger); cursor: pointer; }
.yl-delivery[data-status="failed"]::after { content: "\26A0 "; }
@keyframes yl-pulse { 0%,100%{opacity:0.4} 50%{opacity:1} }

/* --- Input area --- */
.yl-input-area {
  padding: 12px 16px;
  border-top: 1px solid var(--yl-border-color);
  background: var(--yl-bg-secondary);
  display: flex;
  gap: 8px;
  align-items: flex-end;
}

.yl-input-area .yl-chat-inner {
  display: flex;
  gap: 8px;
  align-items: flex-end;
}

.yl-input {
  flex: 1;
  background: var(--yl-input-bg);
  color: var(--yl-input-text);
  border: 1px solid var(--yl-input-border);
  border-radius: var(--yl-input-radius);
  padding: 10px 16px;
  font-family: inherit;
  font-size: 1rem;
  line-height: 1.5;
  min-height: var(--yl-input-height);
  max-height: 150px;
  resize: none;
  outline: none;
  transition: border-color var(--yl-transition);
}
.yl-input:focus {
  border-color: var(--yl-input-focus-border);
}
.yl-input::placeholder { color: var(--yl-ts-color); }

.yl-send-btn {
  width: var(--yl-send-size);
  height: var(--yl-send-size);
  min-width: var(--yl-send-size);
  border-radius: var(--yl-send-radius);
  background: var(--yl-send-bg);
  color: var(--yl-send-text);
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  transition: background var(--yl-transition), transform 0.15s ease;
}
.yl-send-btn:hover { background: var(--yl-accent-hover); }
.yl-send-btn:active { transform: scale(0.92); }

/* --- Button base --- */
.yl-btn {
  padding: 8px 16px;
  border-radius: 8px;
  border: 1px solid var(--yl-border-color);
  background: var(--yl-accent-subtle);
  color: var(--yl-panel-text);
  cursor: pointer;
  font-size: 13px;
  transition: all var(--yl-transition);
}
.yl-btn:hover { background: var(--yl-accent); color: var(--yl-accent-text); }
.yl-btn-primary {
  background: var(--yl-accent);
  color: var(--yl-accent-text);
  border-color: var(--yl-accent);
}
.yl-btn-primary:hover { background: var(--yl-accent-hover); }
.yl-btn-sm { padding: 4px 10px; font-size: 12px; }
.yl-btn-icon {
  width: 36px; height: 36px;
  padding: 0;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 16px;
}

/* --- Settings panel overlay --- */
.yl-settings-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 500;
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--yl-transition), visibility var(--yl-transition);
}
.yl-settings-overlay.open { opacity: 1; visibility: visible; }

.yl-settings-panel {
  position: fixed;
  top: 0; right: 0;
  width: 400px;
  height: 100vh;
  background: var(--yl-panel-bg);
  color: var(--yl-panel-text);
  border-left: 1px solid var(--yl-panel-border);
  overflow-y: auto;
  transform: translateX(100%);
  transition: transform var(--yl-transition);
  z-index: 501;
  padding: 0;
}
.yl-settings-overlay.open .yl-settings-panel { transform: translateX(0); }

.yl-settings-header {
  padding: 16px;
  border-bottom: 1px solid var(--yl-panel-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  background: var(--yl-panel-bg);
  z-index: 1;
}
.yl-settings-header h2 { margin: 0; font-size: 18px; }
.yl-close-btn {
  background: none; border: none; color: var(--yl-panel-text);
  font-size: 24px; cursor: pointer; padding: 4px;
  opacity: 0.6;
}
.yl-close-btn:hover { opacity: 1; }

.yl-settings-tabs {
  display: flex;
  border-bottom: 1px solid var(--yl-panel-border);
  padding: 0 16px;
}
.yl-tab {
  padding: 10px 16px;
  cursor: pointer;
  font-size: 13px;
  border-bottom: 2px solid transparent;
  opacity: 0.6;
  transition: all var(--yl-transition);
}
.yl-tab.active {
  opacity: 1;
  border-bottom-color: var(--yl-accent);
  color: var(--yl-accent);
}

.yl-settings-body { padding: 16px; }

.yl-form-group {
  margin-bottom: 16px;
}
.yl-form-label {
  display: block;
  font-size: 12px;
  margin-bottom: 6px;
  opacity: 0.7;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}
.yl-form-row {
  display: flex;
  gap: 8px;
  align-items: center;
}

.yl-color-input {
  width: 40px; height: 32px;
  border: 2px solid var(--yl-border-color);
  border-radius: 8px;
  cursor: pointer;
  padding: 2px;
  background: transparent;
}
.yl-text-input {
  flex: 1;
  background: var(--yl-input-bg);
  color: var(--yl-input-text);
  border: 1px solid var(--yl-input-border);
  border-radius: 8px;
  padding: 6px 10px;
  font-size: 13px;
}
.yl-range-input {
  flex: 1;
  accent-color: var(--yl-accent);
}
.yl-select-input {
  flex: 1;
  background: var(--yl-input-bg);
  color: var(--yl-input-text);
  border: 1px solid var(--yl-input-border);
  border-radius: 8px;
  padding: 6px 10px;
  font-size: 13px;
}

/* --- Theme grid --- */
.yl-theme-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin-bottom: 16px;
}
.yl-theme-card {
  padding: 12px;
  border-radius: 12px;
  border: 2px solid var(--yl-border-color);
  cursor: pointer;
  transition: all var(--yl-transition);
  text-align: center;
  font-size: 13px;
}
.yl-theme-card:hover { border-color: var(--yl-accent); }
.yl-theme-card.active {
  border-color: var(--yl-accent);
  background: var(--yl-accent-subtle);
}
.yl-theme-card .preview {
  height: 40px;
  border-radius: 8px;
  margin-bottom: 6px;
}

/* ============================================================
   RESPONSIVE: MOBILE
   ============================================================ */

@media (max-width: 768px) {
  html { font-size: var(--yl-font-size-mobile); }

  .yl-msg.them .yl-bubble { max-width: 85%; }
  .yl-msg.me .yl-bubble { max-width: 80%; }

  .yl-settings-panel {
    width: 100%;
    border-left: none;
  }

  .yl-header .yl-menu-btn { display: flex; }

  .yl-chat { padding: 12px 8px; }

  .yl-input-area { padding: 8px 12px; }
}

@media (min-width: 769px) {
  .yl-header .yl-menu-btn { display: none; }
}

/* ============================================================
   ANIMATIONS
   ============================================================ */

@keyframes yl-fade-in {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes yl-slide-up {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

/* --- System message --- */
.yl-msg-system {
  text-align: center;
  padding: 4px 0;
}
.yl-msg-system .yl-bubble {
  display: inline-block;
  background: var(--yl-system-bg);
  color: var(--yl-system-text);
  font-size: var(--yl-system-size);
  border: none;
  padding: 4px 12px;
  border-radius: 12px;
  max-width: 80%;
}