.linear-tool {
  background: #ffffff;

  border: 1px solid var(--math-line);
  border-radius: 18px;

  box-shadow: var(--math-shadow);

  overflow: hidden;
}


.linear-tool-head {
  display: flex;
  align-items: start;
  justify-content: space-between;

  gap: 20px;

  padding: 25px 28px 20px;

  border-bottom: 1px solid var(--math-line);
}


.linear-tool-head h1 {
  margin: 0 0 7px;

  font-size: 30px;
}


.linear-tool-head p {
  margin: 0;

  color: var(--math-text-soft);

  font-size: 13px;
  line-height: 1.7;
}


.linear-grade {
  flex: 0 0 auto;

  padding: 6px 9px;

  background: #fff2da;

  border-radius: 8px;

  color: #9b6416;

  font-size: 11px;
  font-weight: 800;
}


.linear-workspace {
  display: grid;

  grid-template-columns:
    minmax(0, 1.45fr)
    minmax(280px, 0.7fr);
}


.linear-input-panel {
  min-width: 0;

  padding: 25px 28px;

  border-right: 1px solid var(--math-line);
}


.linear-input-panel h2 {
  margin: 0 0 18px;

  font-size: 16px;
}


.linear-equation {
  display: grid;

  grid-template-columns:
    minmax(95px, 1fr)
    54px
    minmax(70px, 0.8fr)
    34px
    minmax(95px, 1fr)
    54px
    minmax(70px, 0.8fr);

  align-items: center;

  gap: 7px;
}


.linear-term {
  position: relative;

  min-width: 0;
}


.linear-term input {
  width: 100%;
  height: 50px;

  padding: 0 32px 0 10px;

  background: #ffffff;

  border: 1px solid var(--math-line);
  border-radius: 9px;

  color: var(--math-text);

  text-align: center;

  font-size: 18px;
  font-weight: 800;

  outline: none;
}


.linear-term span {
  position: absolute;

  top: 50%;
  right: 12px;

  transform: translateY(-50%);

  color: var(--math-text);

  font-size: 18px;
  font-weight: 900;

  pointer-events: none;
}


.linear-equation select,
.linear-number {
  width: 100%;
  height: 50px;

  background: #ffffff;

  border: 1px solid var(--math-line);
  border-radius: 9px;

  color: var(--math-text);

  text-align: center;

  font-size: 17px;
  font-weight: 800;

  outline: none;
}


.linear-equation select {
  padding: 0 8px;

  cursor: pointer;
}


.linear-number {
  padding: 0 8px;
}


.linear-term input:focus,
.linear-equation select:focus,
.linear-number:focus {
  border-color: var(--math-primary);

  box-shadow:
    0 0 0 3px
    rgba(47, 111, 237, 0.1);
}


.linear-equals {
  text-align: center;

  color: var(--math-primary);

  font-size: 23px;
  font-weight: 900;
}


.linear-help {
  margin: 12px 0 0;

  color: var(--math-text-soft);

  text-align: center;

  font-size: 11px;
  line-height: 1.6;
}


.linear-actions {
  display: flex;
  justify-content: center;

  gap: 8px;

  margin-top: 22px;
}


.linear-actions button {
  min-height: 44px;

  border: 0;
  border-radius: 9px;

  font-weight: 800;

  cursor: pointer;
}


.linear-calculate {
  min-width: 165px;

  background: var(--math-primary);

  color: #ffffff;
}


.linear-clear {
  min-width: 76px;

  background: #eef1f6;

  color: #566176;
}


.linear-error {
  margin: 14px 0 0;

  color: #c0392b;

  text-align: center;

  font-size: 12px;
  font-weight: 700;
}


.linear-result-panel {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;

  min-height: 245px;

  padding: 24px;

  background: #f8faff;

  text-align: center;
}


.linear-result-label {
  margin-bottom: 8px;

  color: var(--math-text-soft);

  font-size: 12px;
  font-weight: 800;
}


.linear-result {
  color: var(--math-primary);

  font-size: 40px;
  font-weight: 900;

  line-height: 1.35;
}


.linear-sub-result {
  margin-top: 10px;

  color: var(--math-text-soft);

  font-size: 13px;
  line-height: 1.6;
}


.linear-steps {
  padding: 22px 28px 27px;

  border-top: 1px solid var(--math-line);
}


.linear-steps-head h2 {
  margin: 0 0 12px;

  font-size: 16px;
}


.linear-steps-list {
  display: grid;

  gap: 7px;
}


.linear-step {
  display: flex;

  gap: 12px;

  padding: 10px 12px;

  background: #f7f9fc;

  border-radius: 9px;
}


.linear-step-number {
  flex: 0 0 auto;

  width: 24px;
  height: 24px;

  display: inline-flex;
  align-items: center;
  justify-content: center;

  background: var(--math-primary-soft);

  border-radius: 50%;

  color: var(--math-primary);

  font-size: 11px;
  font-weight: 900;
}


.linear-step-text {
  color: #43506a;

  font-size: 13px;
  line-height: 1.7;
}


.linear-info-grid {
  display: grid;

  grid-template-columns:
    repeat(2, minmax(0, 1fr));

  gap: 10px;

  margin-top: 20px;
}


.linear-info-card {
  padding: 18px;

  background: #ffffff;

  border: 1px solid var(--math-line);
  border-radius: 13px;
}


.linear-info-card h2 {
  margin: 0 0 8px;

  font-size: 15px;
}


.linear-info-card p {
  margin: 0;

  color: var(--math-text-soft);

  font-size: 12px;
  line-height: 1.7;
}


@media (max-width: 820px) {

  .linear-workspace {
    grid-template-columns: 1fr;
  }


  .linear-input-panel {
    border-right: 0;
    border-bottom: 1px solid var(--math-line);
  }


  .linear-result-panel {
    min-height: 165px;
  }

}


@media (max-width: 620px) {

  .linear-tool-head {
    padding: 20px 18px;
  }


  .linear-tool-head h1 {
    font-size: 26px;
  }


  .linear-grade {
    display: none;
  }


  .linear-input-panel {
    padding: 20px 14px;
  }


  .linear-equation {
    grid-template-columns:
      minmax(70px, 1fr)
      48px
      minmax(58px, 0.8fr)
      26px
      minmax(70px, 1fr)
      48px
      minmax(58px, 0.8fr);

    gap: 4px;
  }


  .linear-term input,
  .linear-equation select,
  .linear-number {
    height: 46px;

    font-size: 15px;
  }


  .linear-term input {
    padding-right: 27px;
  }


  .linear-term span {
    right: 9px;

    font-size: 16px;
  }


  .linear-equals {
    font-size: 19px;
  }


  .linear-result {
    font-size: 34px;
  }


  .linear-info-grid {
    grid-template-columns: 1fr;
  }

}


@media (max-width: 420px) {

  .linear-equation {
    grid-template-columns:
      minmax(58px, 1fr)
      42px
      minmax(50px, 0.8fr)
      20px
      minmax(58px, 1fr)
      42px
      minmax(50px, 0.8fr);

    gap: 3px;
  }


  .linear-term input,
  .linear-equation select,
  .linear-number {
    padding-left: 5px;
    padding-right: 5px;

    font-size: 14px;
  }


  .linear-term input {
    padding-right: 23px;
  }


  .linear-term span {
    right: 7px;
  }

}